Wiring Woes....

[Mikelly]

A good multimeter and test light come in handy when dealing with a rats nest of wires like I have wrestled with tonight. Seems my headlights were causing the wires at the switch to get warm. I had to tear out the steering column wiring and test all the wires to see where the suspect smoke came from. Funny thing is, no melting insulation in the wire... Just hot enough to cause the solder to get hot and emmit a little smoke... Now that I have that issue resolved I can go back to wiring in the gauges. I should be driving again by this weekend!

 

Mike

 

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"I will not be a spectator in the sport of life!"

mjk

[SuperDan]

Good luck Mike, at least you are not dealing with 280Z wiring

 

 

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Dan "I need bigger tires" Porter, 78 280Z, 383, 475hp, 700R4 Move outa my WAY!!!

http://24.4.88.44/members/dporter/DanZ.html

[MYRON]

I know exactly how you feel! I had to re-do

and fix all the wiring in my headlight high-beam and turn signals. I also (like a bonehead) managed to melt the big wiring cluster that sits against the trans tunnel

when i was welding underneath the car!

[Owen]

Good luck with it! I'm a bonehead too cuz I didn't label anything when I ripped out my dash to put new meters in. I was hoping the Haynes and Chiltons manuals I have would be a great help, not so!

Now I have to wait until the car is running to see which parts aren't connected right.

Owen

 

 

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http://www.homestead.com/s30z/index.html

 

[This message has been edited by Owen (edited March 22, 2000).]

[pparaska]

I just started the wiring phase of my project. Like most of the rest of anything that does anything on the car, I'm not leaving it stock. The stock Z wiring and switching philosophy appears to be Lucas inspired.

 

The turnsignals, running and headlights, blower fan, and other circuits have no relays. All current gets put through the dash wiring harness and the switches. Stupid design. The switches are overloaded when some other part of the circuit gets corroded connections and the fuse box starts to suffer also. Years ago, after numerous problems with the turnsignals, I put relays in the circuit. See my web page for an article on that. The switches aren't cheap or plentiful, so why not retire them to just handling the tiny current needed to run a relay?

 

Now I'm putting in relays for the headlight and running lights, and the blower fan (I upgraded to a 85 Ford LTD fan wich really kicks out the air so the A/C will work).

Yes, that's three Relays for the blower fan alone. Overkill maybe, but no biggie to me.

I'm also designing a logic circuit to turn on the two speed cooling fan for various states of the coolant temp sensor (GMish from JET) and the trinary switch for the A/C, so that the fan only comes on as needed. This beast takes a 60 amp fuse in the 98 4.6L Mustang. So I have some 70 amp Hella relays for that also.

 

Ain't no way I'm going to have my wiring ruin my day. The Z has a bad history of that happening.

 

Oh yeah, I'm going to replace the AMP meter with a 280Z volt meter also. That Amp meter is a source of dead electrics also.

 

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Pete Paraska - 73 540Z - Marathon Z Project - pparaska@tidalwave.net">pparaska@tidalwave.net -

[Mike kZ]

Pete, are you going to use your Rad fan as a 2 speed or 1 speed? Is that logic circuit to make it run as a 2 speed? If so I'm interested in it because I have a 2 speed fan also.

[pparaska]

Mike kZ,

 

I'm going to use both speeds. The Haynes manual for the Mustang says that the low speed is used when coolant temp gets above 221F and shuts off when it gets below 200F.

Then it says that the high speed is used when the Max A/c is used. Not enough info for me, as what happens when A/C is on, but temp is not high enough to trigger the low speed?

 

Also, I can't tell from the circuits (lot's of black boxes in the schematics) if the low speed winding gets de-energized when the high speed one is energized. I think it ought to be though.

 

The logic circuit I came up with will turn on the fan as such:

 

________________Coolant temp LOW_____Coolant temp HIGH

A/C Press LOW______FAN:OFF___________FAN:LOW

A/C Press HIGH_____FAN:LOW___________FAN:HIGH

 

This way the fan is only on if needed. If I'm running down the rad and it's cool out but I want the A/C on to get defrost action, the fan might not be needed (Coolant temp low, A/C pressure LOW), or the A/C pressure might go high, with the coolant temp low, and only the low speed comes on. Only two Logic gat chips are needed, an AND gate and an XOR gate. I'm going to use the high temp (up to 125 deg C) chips for this circuit.

 

This fan on it's low speed is supposedly more powerful than the flexlite 150 fan, So my logic above may be fine. IF not, it's only a matter of some more Logic gates to change it. Designing stuff is fun for me, so I don't mind if I have to change it.

 

What would be a good improvement is to have two coolant temp sensors, on like I have (on at 200F, off at 185) and a higher one (on at 220F, off at 200F). I may go there if needed.

 

[This message has been edited by pparaska (edited March 23, 2000).]

[Mike kZ]

Pete

 

Does your fan need a resistor for the low speed? Mine does. I'll be using the two temp sensors with relays, and hope that's all I'll need.

[pparaska]

Resistor on low speed? Nope. It uses two windings to get the two speeds. At least that's what I've seen in the schematic. I've yet to put voltage to it. I'll try that this weekend.

 

Pete

[Guest Locutus]

If I remember from my mustang, I believe the fan is supposed to stay on all the time the A/C is on. That is maybe why it isn't clear as to when it goes off during A/C use, it probably was meant to stay on at all times the A/C is on. The other one is temp sensative and should kick on anytime the temps is abouve the required temperature. Even with the car off.

 

Mike

[BLKMGK]

Pete, what did you finally end up doing with your fan? I'm hunting a Mustang fan myself and would be interested in knowing how your setup worked out.

 

Thanks!

[Guest Anonymous]

The only reason the fan comes on at max a/c is for pressure concerns. That makes the system more efficient.Thus it cools better.

[pparaska]

Hey Guys,

 

I built a circuit that uses a several relays and diodes to do the logic and current carrying. With several switches an input to the circuit, I can have the two fan speeds come on in many different schemes, depending on how much I want the fan on and what state the Jet fan switch, the A/C Trinary (cooling fan portion) switch, the A/C clutch, and a manual override switch (4 modes) are at. Pretty complicated, but (4) 30/40 amp relays, on smaller relay, and 4 diodes were all that were needed. I have this mounted in an aluminum box in front of the radiator support (along with two headlight relays).

 

Anyway, I will try it first with the fan coming on as little as possible, and see if I need to have it come on more often and/or at high versus low speed for some modes of the switches.

 

The Mustang (late 90s) has it come on low speed when the engine temps are high, and High speed if the A/C is on. I can duplicate that setup with the flip of a switch on the relay box. That will probably be my first setting to try.

 

I'm still weeks away from having it ready to start, but after that, alot of the car body, glass, interior, lights, etc. have to go on the shell to bea able to really test things. I probably won't know until next Summer how the cooling fan works.

 

I can post the schematic of the circuit if anyone is interested.

 

Power consumption is pretty incredible. 35 amps on high speed and 20 amps on low speed, both measured at 13 Volts.

 

The Mustang electrical system calls for a 60 amp fuse. I'd bet that's for the current spike when you turn on the fan from off to high speed. It spikes to over 80 amps for a second or so, while it winds up. Going from low speed to highs speed and it spikes to around 50 or 60 amps.

 

I have a 60 amp Maxifuse in the common (ground) line of the fan.

[BLKMGK]

Would love to see the schematic. I've not got A/C on my car but I want it I've yet to find a fan but I've got folks looking - how much did yours cost and where did you source it?

 

Pretty incredible load on the alternator! Why did you fuse the ground side instead of the hot side? I'd be worried about something shorting out the hot lead and smoking the wire from the short to the battery. Come to think of it - Painless Wiring's headlight harness has a fuse in the midst of the relays but no fuse up near the battery on the hot lead - will have to fix that! I try to fuse everything as close to the battery as possible, bad things happen if something shorts right at the battery (shiver).

[pparaska]

I totally agree about fusing things near the battery (or alternator), but I use a different tact. I use fusible links for hard shorts and fuses for short, temporary overloads

 

I've become "fusible link man". I put a fusible link right at the source. Since I don't seem to have any allegance to any maker , I use Ford-style fusible links (from the local parts store). They have a nice little plastic tab on the eyelet connector that has the gage of the link on it.

 

I have a starter solenoid about where the stock battery top was, and I run the power for the stock electrical system from that with a 14 gage fusible link connected to the stock 10 gage white wire. I also have a 12 gage fusible link there, which connects to an 8 gage wire to the alternator, which has another 12 gage fusible link on it's output.

Also, off the altenator output, I have another 2 gage fusible link and then 8 gage wire that runs to the fan/headlight relay box that's in front of the radiator support on the right side. Then the wires to go to the two fan windings (low and high speed). Then the common to the 60 amp fuse, then an 8 gage ground wire back to the engine block near the starter where the 2 gage battery cable from the rear mounted battery.

 

So if I have a short anywhere from the remote starter solenoid on, it is either fused or fusible linked. The fuse is for short momentary overloads (hand stuck in the fan blades, etc. , and the fusible link is for major shorts.

 

BTW, Mark at MAD enterprises (seems his web site is down) has the 12 gage fusible links (non-ford-style) and 8 gage "tuff wire". This stuff has really thick, tough insulation that is high heat capable and resistant to under hood chemcials. He's got some really cool electrical parts and kits, and some really good how-to. Call him up and get ready for him to talk your ear off about auto electrics (your nickel, he doesn't have an 800 number).

[Mike kZ]

Hey Pete, how do you know what gauge fusible link to use with what wire gauge?

[pparaska]

Yeah, learned that from Mark and MAD.

 

Take the wire gage number (say 8 gage) and

add 4 to it to get the fusible link gage (12 in this case.

[BLKMGK]

I'll admit to being dirt ignorant where fusible links are concerned - I've just never worked with them. Have you got pics of your car's wiring setup anywhere? Sounds liek I've got a bit to learn about wiring a car correctly Also, what's the MAD URL? I've been having a heck of a time finding an ad for them lately and have yet to search for their site. If you've got it handy along with maybe an URL for your car I'd appreciate it.

 

Thanks for the skoolin'!

[pparaska]

I got my fan from the parts dept at the local Apple Ford Dealer in Columbia MD. He was interested in the project and gave me a hell of a break on the price ($175).

 

I'll work on getting a schematic together that's presentable and post it on my site.

 

I don't have any suitable pics of my car's wiring, but when I'm done I will document it and put it on my site.

 

M.A.D. Enterprises used to have a web site, but I haven't been able to get to it in a while. I think Mark may have taken it down because it was out of date as to what his advice is these days. The guy is incredibly anal retentive, and that's coming from someone else who is! He is a wealth of information. His phone number is 559-539-7128.

 

Jim, I've been playing with electronics since I was a kid. My dad's an electrical engineer and taught me lots of stuff. I've just been researching this fusible link stuff myself lately. Any way I can help with the electrical stuff, ask and I might have some ideas.

 

One thing I've learned is to size wire based on acceptable voltage drop. Look at the total length of the circuit (including ground wires) and the max current draw on it. Then pick a wire gage that gives no more than the allowable voltage drop for that amp load and wire length.

 

For instance, if you have 20 feet total of wire in the circuit, and the circuit needs to carry 35 amps, and you decide on a 1/2 volt acceptable drop, then you use R=V/I to figure the allowable resistance in all the wire:

 

R=.5/35 = 0.0143 ohms.

 

To find out an acceptable ohm/ft value to select the wire gage from, you divide the value of R by the wire length:

 

R/L = .0143/20 ohms/ft = .000715 ohms/ft

or .715 ohms per 1000 ft

 

Then you need to know the resistance per length of the standard wire gages (which I'm going to give you ):

(Reference, Handbook of Chemistry and Physics, 28th edition, 1944 Wire Table, Standard Annealed Copper )

Gauge No.      Ohms/1000 ft   Ohms/1000 ft
             @ 68 degrees F  @ 167 degreesF 
   4/0            0.0490        0.05961
   3/0            0.0618        0.07516
   2/0            0.0779        0.09478
   1/0            0.0983        0.1195
    1             0.1239        0.1507
    2             0.1563        0.1900
    4             0.2485        0.3022
    6             0.3951        0.4805
    8             0.6282        0.7640
   10             0.9989        1.215
   12             1.588         1.931
   14             2.525         3.071
   16             4.016         4.884
   18             6.385         7.765
   20            10.15         12.35
   22            16.14         19.63 
   24            25.67         31.22

Any smaller than that, I don't see a need for. Notice that the resistance per length goes up for a higher temperature (more likely for underhood I guess.)

 

Anyway, for the example above, 8 gage wire would be needed (.764 is close enough to the .715 number), 10 would have too much resistance and voltage drop.

 

School's out! Hope that helps.