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Rumnhammer

Chris Rummel's easy follow RB into Z wireing guide

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Ok, here we go, the following guide, is my compilation of info from this board and others that I used to do the wiring on my friends Z. I made this guide to help others with what can be the most difficult part of any engine swap, even though it is quite simple, it can be intimidating, which is why so many people opt to pay serious cash to have the wiring harnesses done, when you really don't need to. So I deceided to put together a guide that goes though the process I used to get the RB set up and running. From the get go, let me say that you will need to know how do do some basic wiring, ie splicing, soldering, and have a decent knowledge of how wiring works, like reading a schematic and using a test light and multimeter. Now just because I said that don't think it will be any harder, these are simple things and if you can put in your own stereo and feel capable of doing this swap then you can handle this part too.

Next, the disclaimer, although this guide should get you running, missing something along the way or making a mistake, like not disconnecting the battery while doing something etc and frying your ecu or something similar is not my fault, so don't blame me if something like that happens.:icon56:

I'll be trying to make this stuff as clear as possible, but I want this guide to evolve, so if you guys find any part unclear, need a better shot of a connection or whatever don't be afraid to ask, look at it this way if you have the question, then someone else will have it too, and by clarifiying I won't continiue to get that same quesition over and over adnausium.

Finally I want to thank all those that helped me, primarily Myron, Q, Zcarnut, Stony, and Matt Hutchens, and to the HybridZ crew in toto, since most of my info I gleaned from here, I just wanted to give back a bit and turn that info into and easy to follow guide. I will also try to make clear the differences between Z's and note the different ways that you can go with different Z's. The swap I did was an R33 RB25DET into a 75 280Z from California. I got the engine etc from a clip so I'll note what you need to have if you are getting an engine/tranny harness package. I prefer to pull my own stuff from a clip because you get to see the stuff before it is taken appart, and you will know the harness has not been cut in the wrong place and that all the stuff is there, but some people prefer to get an engine/tranny/harness package on a pallet and that is ok too, just need to get it from somewhere reliable. This is an RB25DET but a RB26DEtt should be similar, I haven't done that swap so you are on your own with the differences. I also suggest you print out one of the available ecu pinout diagrams availible on here to help and a schematic of the RB and the Z car will be helpful as well.

 

 

With that lets go. This first pic you see the general reason why this can be intimidating. This is a shot of the engine harness that covers running the fuel injection. For Those getting a engine/Tranny/harness package, which will here after be refered to as an ETH, you will want to make sure that you have all the harness off of the engine as it goes through the firewall with the gromet and the ecu plug, this should also contain the eccs relay, and the main fuel injection relay, (they are side by side near the ecu plug) you will also need the ecu, and the main white plug that the ecu/engine harness connects to the rest of the skylines in car harness. you should preferably have about 3 feet or so of wire off the back of the white connector that would normally go to the ignition switch and other things inside the car. So if you pull it from a clip get that, if you get an ETH request it from who you are buying if from you can do the wiring without the white connector, but I found it made locating the wires and routing easier. You will also have a separate harness that goes to the tranny, alternator, starter, main hot, and IAC valve, you can do the wireing again without this separate harness and hook up the Z stuff on this side, but I found it easier to use the skyline tranny harness and splice it into the Z harness.

 

RBZwire007.jpg

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This shot shows, the main injector harness overall, removed from the white connector that goes to the rest of the car. the two white connectors in the front are what goe into the main white connector that I'll show you in a minute. To the right of that is the rest of the harness as it goes out into the engine compartment note the gromet for the firewall.

To the left of the white connections you see the main injection power relay and eccs relay twins, then finally left of that the ecu plug.

The first thing you want to do is remove the tape and covering from the harness up to the grommet. If you are doing a 240z you need not have done anything up to this point, to the car wiring wise. For a 280z before getting to this step you should have removed the engine and all the FUEL INJECTION WIRING from the car, it's pretty easy basically all the stuff on the left hand (drivers side U.S.) side of the car. Remove it all compleatly from the car, this includes the ecu, the stock fuel injection/fuel pump relays, the dropping resistors, grommet and all that stuff. You don't need to worry about the wiring on the passenger side of the car in the engine compartment.

 

RBZwire041.jpg

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This is a closer shot of the end with the ecu plug, notice all the harness tape stripped off, and the white plastic cover that goes over the end of the ecu plug pulled back, this will make tracing wires easier and you will remove some stiffeners and hard plastic pieces that will make placing this harness where it needs to go easier later. (trust me)

 

RBZwire042.jpg

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This shot shows the Main white connector. You don't need this per-se, but it plugs directly into the fuel injection/ecu harness and already has wires attached to it to make your connections so I recommend you get it.

You are only going to need a few wires off of it so don't get spooked with all the wires coming off it. We will be making this much smaller, first thing you need to do is cut off this big piece of extranious white plastic, seen to the left of the white connector already cut off in this pic, also note all the harness tape has been removed. we are going to separate out the few wires, we need coming off this connector and leave them about 3 feet long, the ones we are not using will be cut off short and taped up to make this all smaller, again to fit easier in the space we are going to put it in.

 

RBZwire040.jpg

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Ok, now we are going to separate out the wires we are going to need to hook up, leave these long and cut the rest off short and tape them up.

 

The first wire is thin grey/red stripe this is wire AF09 the starter wire, you can trace it from pin 43 on the ecu.

 

The next wire is Thick Black/red stripe this is wire AF36 the main ignition power wire you can trace it to pin 45 on the ecu.

 

The next wire is the Thick solid red wire AF04 this is the main power for the fuel injection and goes to the ignition power relay

 

Next use a multimeter to trace the wire that comes off of pin 58 on the ecu it is thin white with black stripe this is battery back up/memory power for the ecu.

 

The next wire is Thin black/pink stripe #AF73 and goe to pin 18 on the ecu. This is the fuel pump signal, it's a switched ground signal that you use for your ground to switch your fuel pump relay,(I'll show how to wire that up later)

 

The next wire is Thin red/white stripe #AF10 from pin 32 off the ecu, also a switched ground this is the check engine light signal, use this as the ground side off a light that you can put in the dash, use a hot when on on the other side of the light for juice. This is not nessiary for the engine to start and run, but it is good to have for diagnosis of any ecu or sensor problems. I used the catalist light in the dash, since it is no longer needed for the cat. :mrgreen:

 

The next wire is MF01 thin yellow/blue stripe that goes to pin 7 on the ecu this is the tach out signal for the tach. This is only needed if you are using the RB gauge cluster, because it is multiplexed and will not supply a good tach signal if you are using an aftermarket tach like I did. If you are using an Autometer, you will need to use a tach adapter (I'll show how to wire that later too) and you don't need to worry about this wire.

 

The next wire is Thin light blue, #AF99 this is the air regulator wire

 

Next wire is Thin blue/black stripe MA26 this is the water temperature signal (the one that goes to the stock Z gauge)

 

Next wire is thin blue/white stripe, #AF37 this is the power wire for the VTC, AAC valve, 02 sensor, and stock boost control solinoid.

 

lastly the main solid black ground, this is easy to see it consolidates all the grounds and ends in a ring terminal

 

Separate all these wires from the rest and leave them about 3 feet long, all the rest coming off the white connector can be cut off short and taped up, when you are done you have something that looks like this.

 

RBZwire012.jpg

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Next you are going to gain access to your ignition switch, you know that thing you stick the key in and turn the car on.:icon56:

 

For those with 240z's and possibly 260's you will be making your connections here, for those with a 280z, you guys have it easier as your connections are almost plug and play since there is a plug that goes up to these wires on the fuel injected cars.

 

Note the colors here because I'll be refering to them for the hot connections. you have Thick white/red stripe this is constant hot it always has power.

 

Thick black/yellow stripe this is the ignition start signal wire.

and Thick black/white stripe this is hot when on, in other words when the key switch is turned to the on position then this wire has power.

 

to see what is in this pic you just need to unplug this from the back of the key switch. for those with a 280z you still need to find this so you can test for the wires at the plug that I'm going to refer to.

 

RBZwire008.jpg

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For the guys with 280z's look just right of your hood release pull, you will see a plug that has 2 green wires and 2 white wires coming out of it, when you remove all the stock fuel injection wireing DO NOT DISCARD THIS PLUG, but cut it off the old injection harness leaving about 4 inches of wire, this is what you guys are going to wire into for the hot when on and starter signal, and if you use this then you can just plug that baby in like factory, it doesnt get any better then that.

 

RBZwire009.jpg

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In this shot you see the plug pluged in and the wires that you are going to connect to hanging down.

 

You will only be using the 2 white wires, with it pluged in like this use the multimeter to find the hot when on, (goes to the black/white stripe at the start switch) and the other one will be the start signal wire.

 

RBZwire010.jpg

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Ok, I got a little ahead of myself so lets backtrack a bit, by the time you are doing this wiring hook up you should have already brought the ecu plug end of the harness though the firewall, on the 280z you will bring the harness through the same hole in the drivers side foot well and the ecu will mount in the same place as the stock ecu :mrgreen: . This is why you needed to strip off all the extraninous stiffeners and crap out of the harness in this area, because you need to stuff the relay twins, the white plastic connector, and about a foot of wire after it comes though the firewall up in the area above where the old ecu was. The RB ecu will mount in the same place as the stock L28 ecu so you need to have the ecu plug come down like the old ecu plug did. the relay twins, and all the rest will stuff into the area that is shared by the turn signal relay. It will fit trust me. You will need to enlarge the hole that the harness goes through since the l28 harness grommet is 2 inch and the RB's is like 2 1/4

This area is really tight so I used a dremel to enlarge the hole, then you feed the harness in to the hole from the engine side, it is self explanitory when you do it. For 240z guys you really won't be able to get a drill with a hole saw up in this area so I suggest you use an 2 1/4 inch hole saw and make your harness come though in the passenger side foot well area.

You guys will of course have to lengthen the wires that go to the MAF etc then on the drivers side to get them over there. You will also need to add a fuel return line on the carbed cars.

Be sure and use shelded wire for the MAF wires and the O2 sensor wires when you lengthen them. Ok back on track, now we are going to connect some hots.

 

For guys with 240z's You take your thick solid red wire #AF04 and the thin white with black stripe wire that goes to pin 58 and connect both of them to the thick white with red stripe at the ignition switch.

 

For 280z guys you have a Thick solid red wire that goes straight to the battery via a fuseable link, this is what originally powered your fuel injection main relay and so you attach the two wires above to this wire, or if you prefer you can also attach it to the white with red stripe like the 240z guys, but I figured since this wire was already there, and was used for exactly the same function I decieded to use it.

 

Next for 240z's you take the Thick black/with red stripe wire #AF36 and connect it to the thick black/white stripe at the ignition switch.

For 280z's you connect this wire to the white wire from the plug that you traced to go to the thick black/white stripe wire.

 

Next for 240z's you take the thin grey/with red stripe wire #AF09 starter signal wire and connect it to the Black/yellow stripe wire at the ignition switch, for 280z's you connect this wire to the other white wire that remains from the plug.

 

This pic shows the plug with the 280z's connections.

RBZwire031.jpg

 

 

This pic shows the wires ready to be connected

 

RBZwire021.jpg

 

 

this one shows the starter signal connected

 

RBZwire019.jpg

 

and this one shows the main red and ecu battery backup connected to the main hot from the battery.

 

RBZwire022.jpg

 

and this one basically shows how all the wiring should go up in there.

 

RBZwire017.jpg

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Next you are going to take your fuel pump signal wire, the check engine light signal wire, and your water temp gauge wire and run them to the right. for the check engine light wire I took it to the catalist light, otherwise you can add a small light bulb to the dash to use for this.

 

Tap into a hot when on wire and run that as your hot to your light, then connect your check engine signal wire as the ground. here is a pic wired up this way to the catalist light connector.

 

RBZwire035.jpg

 

 

Next take your Water temp gauge wire signal MA26 blue/black stripe wire and take it up to your stock temp gauge. remove the gauge and locate the plug on the back of it. you will see a yellow/white stripe wire on the back of it. unplug the gauge and at the connector that hangs down cut the yellow/white stripe wire or tap into it like I did. Note that the RB sender signal will not jive with the stock Z gauge so get the Z car sender out of your old L series engine to use for a proper signal, either that or use an aftermarket gauge. In this pic you see the back of the gauge with my fingers showing the yellow/white stripe wire.

 

RBZwire029.jpg

 

and in this pic you see the wire tapped into the yellow/white wire at the connector.

RBZwire030.jpg

 

The fuel pump signal wire you will be using for the ground on your fuel pump relay, this way the ecu has control of the fuel pump and will shut the pump off if the engine is not rotating, a good safety feature.

This one has probably the most variations, since early 280zs like this one had the fuel pump relay as part of the fuel injection relay and later ones have a separate one, I would say on the later z's run this in lieu of the one that came from the ecu to your relay, on early 280's you can do Like I did and use a generic 30 amp relay that runs straight to the battery using 10 gauge wire for the power supply. For this car I replaced the old pump with a universal walbro inline pump and mounted it in the stock location, abet with a bit of modding to the mount and removal of the pulse damper. You guys with 240'z's will need to add a pump like this anyway so you can use this info too. anyway run this wire accross to near the main fuse box in the passenger footwell, and use this wire as your ground on the relay, for the power supply to the relay run a 30amp fused 10 gauge wire from the battery to the input side of the relay then a 10 gauge wire out of the relay to the pump. For the other hot, to trigger the relay, look to the left of where I mounted the relay you will see a main connector, locate the thick black wire/white stripe going into a brown connector this is a hot when on. verify with a test light. for this I tapped it and ran one wire to the pump relay the other one I ran forward into the engine compartment to use as the sensor wire for the alternator through the voltage regulator delesion.

 

In this blurry pic you see the hot when on tap

 

RBZwire032.jpg

 

In this one you see the pump signal wire routed and the tap again

 

RBZwire1002.jpg

 

this shot shows the mounting of the fuel pump relay.

RBZwire1001.jpg

 

finally this shows the mounting of the fuel pump itself.

 

 

RBZwire1003.jpg

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Next we are going to give the fuel injectors and air regulator some juice, I didn't do this originally and the car would not start :icon56:

 

So you need to do this. locate the AF36 wire you already connected at the switch or plug and get about 6 feet of at least 18 gauge wire. Take a vampire connector and tap into the AF36 wire with the light blue AF99 wire and one end of your 6 foot wire like in this pic. You can also add the blue/white VTC power wire into this vampire clip to power it up too. Note the engine will start and run without the VTC wire, as I powered this up later. This wire also powers the AAC valve, and powers the 02 sensor, so I have to drive the car again to see if it improves driveablity. hope so.

 

 

RBZwire034.jpg

 

now take the other end of your 6 foot wire and run it out though the firewall into the engine compartment. Next locate the part of the engine harness that has the MAF connector on it. It should be on the drivers side of the car. Find the MAF connector and keep going to the end of the harness, you will find an 8 plug connector that used to connect to the front harness in the skyline, add a insulated spade connector to the end of your long wire and locate the thin solid gray wire in the 8plug connector. plug your wire into this connection. There! you just powered up the fuel injectors.

see in this pic

RBZwire033.jpg

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Next you take the Tranny harnesses both Z and RB and use your oil pressure sender from the Z to that you connect the green wire like stock like this pic you can wire back the RB sender wire

 

RBZwire016.jpg

 

Then connect the 2 starter signal wires Yellow for Z and black/white RB like in this pic

 

RBZwire015.jpg

 

Next connect the reverse switch wires from the z harness to the sender wires for that on the RB harness and do the same for the neutral switch like in this pic

 

RBZwire014.jpg

 

 

You don't need to connect the speedo sender as this will only enable the top speed cut and you don' t want that do you? besides you will use this speedo sender to send a signal for the aftermarket speedo like the Autometer I used.

 

next if you use a greddy intake you will need to lengthen the two wires that go to the IAC valve since it is relocated I had already lengthend this since the plug is a bitch to get to even off the engine see this pic.

 

RBZwire013.jpg

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Next if you have already converted your external voltage regulator you can skip ahead, but the posted convertions would not work for the 75 Z since it didnt' have a wire for sensing hot when on load, so that wire I tapped for the fuel pump relay switch hot I also ran forward into the engine compartment and ran it straight though the old connector, this comes out of the top the connector and connects to the white/black stripe wire that goes to the alternator L connection BEFORE IT GETS TO THE L CONNECTION THOUGH you wire in a diode per the regulator elimiation instructions with the gray stripe end towards the alternator like in this pic, it also shows the Yellow wire spliced into the S connection which on my RB plug was light green with red stripe.

 

RBZwire027.jpg

 

The yellow wire as it comes out of the voltage reg connector goes straight to the battery or in my case the isolator hot I made.

like in this pic

 

RBZwire026.jpg

 

and this one.

 

RBZwire025.jpg

 

Next at the alternator you can now just plug in the RB plug, the main Z harness alternator hot connection you connect to the RB main hot that goes to the same place, same with the main ground that goes there.

 

Then you hook up the starter just like before and make sure all your grounds are connected note in the above pic I made an isolator block by cutting the one out of the RB fuse box. I did this to make the main hot bolt right up and make my hot connections easy to hook up. I also elimianted the external voltage regulator because it is not needed anymore, and ditched the big old bracket that used to house the shunt and fusable links you can see in the pic that I now attached these to the fenderwell I then added a piece of rubber inner tube to cover all this and keep water off the hots. turned out really well.

 

And So there you have it, follow these instructions and your car should start and run. I'll post the Autometer speedo intructions, the tach instructions and the water temp gauge instructions separately because it is late and I'm getting punchy so I just wanted to get this info out there, now someone please make it a sticky for me.:)

 

If you have questions don't be afraid to ask.

Chris Rummel

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This is just a quicky, When you add an Autometer tach you need to use a tach adapter. For the most part you can just follow the directions, but you do need to find the main power wire to cut so the adapter can intercept the signal and give a good reading to the tach. In the case of the RB it is the main power to the coilpacks. This white wire that I have shown in this pic. you also see a good place to mount the adapter in this pic. Also in this pic you can see how I converted the linkage on the throttle to work with a cable from a Z31. The main bracket that normally goes in this place, I recycled and made basically a firewall going towards the passenger side and welded it to the bracket, then I cut the top off a second gas pedal and welded it to the small nut that goes on the end of the stock linkage rod. works perfectly.

 

RBZ1001.jpg

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Hi again, this time I'm adding how to make the stock Z car gauge work after swaping the RB in. The RB water temp gauge sender will not send the correct signal to the stock Z car gauge.

If the stock Z car gauge works then why not keep it? After all, gauges are expensive and the way the Z has double gauges means that if you are looking to replace them, you need to find extra space, or add extra gauge pods, not to mention the extra expense of buying aftermarket gauges. My friend asked me to keep the stock gauges because he couldn't justify the extra expense of replacing gauges that work fine, with aftermarket for no reason, and didn't want to add a bunch of pods or sacrifice vents to add extra stuff. I had to agree with him, and we decieded to keep the secondary gauges stock replacing only the speedo, tach and clock.

The clock was removed and I gutted it and recycled the housing to fit the boost gauge, that way it mounts just like the clock did. No real loss since the Z car clocks rarely keep good time anyway and he will have a clock funtion on his stereo anyway. The tach was replaced and the tach adapter fitted for proper use. The other gauges were left stock. I didn't touch the amp gauge/fuel gauge combo since I didn't touch anything that conserned them. Personally I would have replaced this with a voltmeter/fuel gauge from a later model Z, but since it still worked I didn't mess with it.

The other gauge combo, the oil pressure worked, because I replaced the RB pressure sender with the stock Z car pressure sender, it goes right on, then you just reconnect the green sender wire just like stock. That just left the water temp gauge not working. To do the wiring part of this just splice in like I outlined earlier in this guide, the only problem is the RB uses a modern thermister sender and the Z gauge uses an older style sender that reads a different resistance so the RB one won't work. I did a bunch of research to see if any other Nissan senders would give the right resistance but came up empty, so that means I would need to use the stock Z sender. I got the old sender back from the guy I gave the L-28 to, only new problem is the old sender is much larger then the new one so it will not just screw in place of the RB sender. Originally I suggested you drill out and tap the location of RB sender on the intake manifold but if you look at that there is not much meat in that area and it is pretty tight as well. That option was out of the question as well because taking off the intake manifold at this point just to do that would be labor intensive.

So I looked for a solution to the problem, and found it with the Autometer in hose sender adapter. This comes as a small kit with an aluminum pipe fitting that goes into your upper radiator hose, it also comes with a brass fitting, a ground wire and 2 hose clamps.

The first thing I tried was screwing the sender directly into the hose adapter, this almost worked, but there are only a few threads in the adapter, and it is not real tight, also if you are useing a new sender it uses a retaining nut to hold the sender in place, mine is 30 years old and long since welded itself together. Using the brass adapter is the way to go but you need to use caution. The first thing you need to do is drill out the hole that goes though it so you can fit the sender in to the point where you can engage the threads on the securing nut. a 1/2inch bit will do this part, then you need to bore it out for th lower part of the sender this is done with a 9/16 bit after you do that the sender will seat into the brass adapter, the threads are real close, the Z's being metric and the adapter being SAE/NPT they are so close that it will screw in, and using some teflon tape it will work well. After you screw the sender into the modified brass adapter, you then screw that into the hose adapter. THIS IS THE PART TO USE CAUTION. Since you have bored out the brass adapter it makes the threaded section very fragile, only screw it in until it is snug, I kept going and the brass threaded section broke off in the hose adapter! That left me to extract the threads from the delicate aluminum adapter with chisels and punches, not a lot of fun!

Use teflon tape on this connection too. then you add a grounding wire to the supplyed thread and cut your upper radiator hose, removing about an inch of it and add the adapter in line. Then I used a spade connector on one end of a small piece of wire and an insulated plug connector on the end to extend and make the wire going to the sender plug and play.

Thats it! Now your stock Z car temp gauge will work just like before.

 

This first pic shows the adapter already modifed, and ready to go in, note that your brass adapter will not be as far in as this, when mine broke off it left 3 threads (really all that is needed) so I was able to clean up the theads on the adapter and use it still.

 

temppic1001.jpg

 

 

This pic is one shot of the adapter in place in the hose.

 

temppic1002.jpg

 

 

And finally this shot from the other side that better shows the wireing mod.

 

temppic1003.jpg

 

Chris Rummel

 

EDit I just found out from someone answering a post as to what sender to replace the RB one with, you can skip the above step if you replace your RB sender with a toyota sender part #TS198 that goes in where the RB sender is and will make your stock Z gauge work.

Chris Rummel

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Note I edited the wiring to show powering up the VTC, I took the first test drive today, and I was really disappointed by the low speed driveabilty. The car wants to stall and is hesitant to rev up. once the engine is reved up and the boost kicks in it flys, This got me to thinking about the VTC, so I checked a second schematic and confermed that it is not connected to the eccs relay for power, I assumed it was until I checked the power to it with a test light and low and behold no power, so I went back to the schematic, and it turns out that not only does this wire which is Blue/white stripe power the VTC but also the AAC valve, and power to the 02 sensor, so that could be part of the problem, it was too late to test drive it again tonight, but I powered up the wire by vampireing into the hot when on connection near where I powered up the fuel injectors. I also edited the info earlier in this guide where you separate out the wires, and where you power it up. So if you haven't followed this guide yet you won't miss hooking this wire up.

Arent' you guys glad I'm finding all this stuff out now so you wont' feel as bad as I did, when I took the owner for a test drive today, good thing he is my best friend, because he was very understanding. I thought it was not running well and litteraly felt like crawling into a hole.

Chris Rummel

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