Wiring questions?? '77 280Z to '90 TPI & T-5

[sstallings]

strotter,

Thanks for the explanation. That clears up al ot of confusion. So, if I'm following your explanation accurately, I can use 532 and 533 to trigger deja's comination of added NO and NC relays (I'll figure out which is which when I draw it myself) and wire my Vintage Air trinary pressure switch into the BC9 circuit, I should be emulating the factory wiring intent for a Taurus single two-speed fan where they used two single-speed fans. That seems pretty straight forward.

 

Note: I found the equivalent information on pages 6E3-C12-2 for the cooling circuit and 6E3-C12-4 for the AC pressure cicuit in my '90 manual. (Talk about a circumspect way of showing this whole process - but I wouldn't have found it at all without yor diagram - so I'm learning more with every step.)

 

Also, thanks for the explanation of the high and low states for the ECM pins. That will also clear up a lot of confusion. I may get through this build yet.

Thanks again,

Steve

[strotter]

Like I said man, this is the part that's most fun - figuring stuff out, making it work, making it elegant. I've been working on a new wiring diagram using OmniGraffle, a general purpose diagramming program. It includes all the same components as before, but I've added all the little "goodies" that have been added over the years - the wideband, the a/c system, the audio gear, modifications to the instrumentation, so on. And, I've actually gone out to my car and confirmed the colors of the wires ('cause the indicated colors of some appear to have been randomly mixed in the factory diagrams). I'll post a copy of it when it's workable. Have fun!

 

W/R/T the trinary switch - I think, when it's done, I won't be using the "trinary" part of the trinary switch, only the plain old "binary" part. The trinary switch is just two switches in parallel rather than one, BTW. I don't think both will be needed. That functionality will come (I think, it's all in the details) from the ECM itself. Has yet to be determined.

[sstallings]

strotter,

Thanks for the clarification. In my '90 Firebird manual, they spread this information over two pages (talk about not being straight forward) but based on your chart from 6E3-A-6 above, I was able to find mine spread across 6E3-C-12-2 where they start to cover the dual fan relay circuit, and 6E3-C-12-4 where they cover the AC high pressure switch operation in part only. It would have been much harder to find any of this without your post.

 

It looks like I can use the same circuit design that GM uses for two fans to control the Ford two-speed fan via the ECM simply by adding the two relays in Deja's circuit as one 70 amp NC and one 70 amp NO to handle the switched on/off/on of high and low settings. On my ECM it looks like pins GE8 and BD12, but not BC9 as on yours (It looks like my AC Request Signal is ECM pin B8, but if I'm not using the factory AC, I'm not sure how that helps me). Once I get the Vintage Air trinary switch installed I can add another relay for the AC pressure (probably a 30 amp NO) since it simply triggers the 70 amp relay and doesn't interface directly with the fan, based on Deja's circuit as well.

Thanks again,

Steve

[deja]

From the way I understand the trinity and binary switch from Vintage is the AC enable is wired from the Vintage Condensor (blue wire) through the binary switch to the compressor. If the pressure gets too high in the dryer the binary switch will open and the compresor will shut down. I believe the trinary switch will turn on the fan at a lower pressure. I wish I had gotten the trinary switch, but its all charged now so I will use the binary switch to run the low speed fan any time the AC is on.

 

Once I get the Vintage Air trinary switch installed I can add another relay for the AC pressure (probably a 30 amp NO) since it simply triggers the 70 amp relay and doesn't interface directly with the fan, based on Deja's circuit as well.

Thanks again,

Steve

[strotter]

I normally don't like to do "I'm gonna -" posts, as they seem never to come to pass, but I'm making an exception here because others are doing the same work right now, so I thought I'd share as soon as I had even a working idea.

 

OK, I've been working on this thing, trying to use all the functionality GM built into the 7730 ECM, while keeping the parts count as low as possible. I did some research (mostly here) on different wiring setups for different models. I finally came on the simplest of all, for an '87 Corsica/Beretta 2.8, 3spd automatic. Here it is:

 

 

As you can see, this is a pretty straightforward setup, so I used it as inspiration. I came up with a simpler relay logic circuit than deja's, using two big relays and one small. I can get away with this because most of the system's operation is controlled by the ECM - there is no physical connection between the a/c system and the fan control system.

 

 

This setup also uses the "primary" circuit to drive the fan at low speed, and "secondary" fan control circuit to drive the fan on high. When the high-speed circuit comes on, though, the little SPDT relay in the middle (used as "Normally Closed") opens and disables the low-speed circuit. The ECM "knows" when the a/c is on when the binary switch closes, via C9 going high. This part is similar to what Vintage Air shows on their wiring diagrams, though they drive a relay for the fan motor. I am a bit concerned abut this - it might cycle the fan on and off quite a bit, stumbling the engine each time. We'll see - I think I can tune it out for most conditions. If it's a problem, I'll use some other hot wire in the Vintage Air system, so as to keep the C9 signal high the whole time the a/c is on.

 

The tuning logic is below the appropriate pins.

 

The a/c "off" logic I'm starting with is as follows: the low-speed primary comes on at 85°C (180°F). As the coolant gets hotter, the high-speed secondary comes on at 95°C (203°F). When that happens, the hot wire from the secondary energizes the little relay, opening the contact and shutting off the signal from the ECM to primary relay, which de-energizes. All happy.

 

The a/c "on" logic is: the secondary is turned on with the a/c, fan is on high. When the a/c cycles off, and if the coolant is below 85, the fan shuts off with the compressor clutch. When the temp gets above 85, instead of shutting off with the compressor the fan drops from high speed to low, maintaining cooling. If the temp should continue to rise above 95, it stays on high regardless of the compressor clutch state.

 

I'm sure there will be changes before I'm done, but I think this might be a workable system. Any critique or suggestions would be greatly appreciated.

[deja]

I may not be thinking right this morning but it looks to me your high speed fan will come on when the low enable goes to ground. Then when the high enable goes to ground the high speed fan will turn off and the low speed fan will turn on. Do you have the schematic labeled backwards for the fan low and fan high? Also are you sure the Vintage air thermostat request is +5v?

[strotter]

OK, there's a typo; the "High Fan" and "Low Fan" note at the right side of the sketch, as well as those below the relays, are backwards: the upper wire & relay feeds the low-speed circuit, the lower wire and relay feeds the high-speed / a/c circuit. It *should* look like this:

 

 

I *think* that fixes the problem you're talking about. I can't believe I let that slip by; it's in my wiring diagram, too. Should I go back and change the link to the erroneous picture, so future readers aren't confused?

 

Also, I've confirmed that the blue wire running to the compressor clutch from the binary/trinary switch is the *only* wire running there; I'm assuming it's +12V and the clutch grounds through its' mount.

 

So does it look it'll work now?

[deja]

LOL, been there done that. I looked at your original schematic a dozen times thinking I was missing something before I posted.

Yes, the blue wire coming from the Vintage thremostat and going through the binary/trinary switch is +12v. My question is the line you have going to your computer says +5v, where are you picking up that? If you use a +12v signal as an input to your computer thats expecting a +5v signal you will somke the computer. There is a ground connection on the compressor connector, you should run it to a good frame ground.

 

 

I *think* that fixes the problem you're talking about. I can't believe I let that slip by; it's in my wiring diagram, too. Should I go back and change the link to the erroneous picture, so future readers aren't confused?

 

Also, I've confirmed that the blue wire running to the compressor clutch from the binary/trinary switch is the *only* wire running there; I'm assuming it's +12V and the clutch grounds through its' mount.

 

So does it look it'll work now?

[strotter]

OK, there's another typo...

 

Yeah, it's 12V. What little I know about this stuff I learned from digital circuitry, where 5V is the standard. It just keeps popping into my head when I think "Positive potential". I guess I'm lucky I don't type "-5" instead of "Gnd"!

 

I'm not going to upload another image with this fix until after I've gotten it installed and tested. I've about filled up HZ's server with bad diagrams, there's no reason to add more "theoretical" diagrams until there's some proof it'll work.

 

Later

[deja]

LOL, I'm a digital tech. +5v is about ancient history these days with the new processor technology.

OK, there's another typo...

 

Yeah, it's 12V. What little I know about this stuff I learned from digital circuitry, where 5V is the standard. It just keeps popping into my head when I think "Positive potential". I guess I'm lucky I don't type "-5" instead of "Gnd"!

 

I'm not going to upload another image with this fix until after I've gotten it installed and tested. I've about filled up HZ's server with bad diagrams, there's no reason to add more "theoretical" diagrams until there's some proof it'll work.

 

Later

[strotter]

OK, I've been fighting with this thing for more than a week now, but I've come up on the limit of my understanding. I need help. Here's what has been happening:

 

 

First: I wanted to confirm my understanding of the behavior of the two fan circuits - E8 and F8 - so I spiced the +12 from the binary/trinary switch to C9, the "A/C Request Signal" input, hooked up a couple of lights to the outputs, started the motor, and turned on the a/c. E8 went low. OK. Coolant temp was 50-some degrees C.

 

Second: Understanding that E8 went off with the a/c, rather than F8, I went in and modified the tune and loaded it into the Romulator. The fans were set to:

 

Fan 2 as "low" fan: 87°C Enable, 85°C Disable

Fan 1 as "high" fan: 97°C Enable, 95°C Disable

 

Third: To confirm, I unhooked the connections to E8 and F8 to disable the fans, with the engine idling:

At startup, Coolant at 70°C, nothing low.

At 89°C, F8 went low, stayed low

At 99°C, E8 went low, too.

I don't know why they didn't go off at exactly the values I set. I'm looking into that, too.

 

Conclusion: "Fan 1" is F8. "Fan 2" is E8. The a/c input to C9 triggers E8. My original assumptions were backward.

 

This seems all pretty easy so far, eh? Not so fast, Masked Man...

 

Fourth: Full of "I'm the man", I hooked all the relays up to the fans as per the information above, started the motor. Coolant at about 60°C. I turned the a/c on, the high fan came on immediately, luxurious cold air blasted out of the vents. Yes, it's true, I rock. I turned off the a/c to wait for the low-speed fan to come on, the a/c shuts off, but there's a buzzing - a loud buzzing - wha?

 

The low-speed relay was buzzing like, well, a buzzer. Loud, 'cause it's a big relay. I'm freaking out, I shut the motor off and grabbed the fire extinguisher, but nothing happened. I checked the wiring, it was OK, so I started digging.

 

Some interesting things came up. I noticed, for instance, that when the high speed fan comes on, there's considerable voltage coming back out of the low-speed hot lead - 7.5 +/- big-fat-spark kind of amperage. I'm thinking this is wrong, so I did some more research on the 'web and came across a reference to a 3V diode being placed by the factory between the low-speed hot lead and the fan. It generally refers to "back EMF", which is voltage generated when a motor has been shut off but is still spinning, like a generator. This can be bad for the relay, I understand, so the diode shorts it to ground. Off to RadShack, bought a big diode, attached it to the leads at the relay. Bzzzzz. OK, maybe bad relays. Hopped in the car off to Pick'nPull, found some big relays (and another Taurus fan just in case), brought them back, installed them, bzzzzz.

 

So now I'm getting ready to pull the current fan and install my new one. I don't want to, it's hot and I'm tired. Am I going down the wrong road, or is this be a problem with the fan, or have I missed some subtle electric thing? Is the configuration of the relays wrong? Is there some mysterious electricity coming from nowhere? I can't for the life of me figure out what I've done wrong.

 

Help!

[deja]

Which relay is buzzing?

Are you sure those on/off settings on you PCM are working?

If your low speed fan relay is turning off when the high speed relay turns on you should be fine.

[strotter]

Which relay is buzzing?

The low speed relay.

Are you sure those on/off settings on you PCM are working?

Yeah, I attached a pair of lights to E8 and F8. They popped on when they were supposed to.

If your low speed fan relay is turning off when the high speed relay turns on you should be fine.

Aye, there's the rub. When the high-speed fan comes on, it works fine; when it goes off, whether it's from the a/c turning off or the coolant cooling down, the low speed relay goes nuts.

 

 

I've been researching "buzzing relays" and "relays Taurus", and came upon another configuration for high and low speed Taurus fans by lsejlowe over at digitalcorvettes.

 

 

I'll be modifying this setup, but you get the idea. This allows the use of only two relays, one spst the other spdt, though I'm thinking I should gang two of the spdt relays I got at the junk yard the other day for the high-power side (I don't know the ratings, though I'm morally sure they're at least 25A). I'm hoping that won't overload the input to the ECM, we'll see. I'll try the configuration this evening on my "testbed" (the new fan, a bunch of wires, and my giant battery charger) and get back to you.

[deja]

You're not going to hurt the EMC. The EMC only activates the coils of the relays which draw minimal current and has nothing to do with the current that the fan draws. The fan current is switched through the contacts.

 

I'm sticking to what I have, no issues at all. I am updating my relay to 70A ones I picked up on EBay but other than that I'm sticking with my original circuit.

 

The low speed relay.

 

Yeah, I attached a pair of lights to E8 and F8. They popped on when they were supposed to.

 

Aye, there's the rub. When the high-speed fan comes on, it works fine; when it goes off, whether it's from the a/c turning off or the coolant cooling down, the low speed relay goes nuts.

 

 

I've been researching "buzzing relays" and "relays Taurus", and came upon another configuration for high and low speed Taurus fans by lsejlowe over at digitalcorvettes.

 

 

I'll be modifying this setup, but you get the idea. This allows the use of only two relays, one spst the other spdt, though I'm thinking I should gang two of the spdt relays I got at the junk yard the other day for the high-power side (I don't know the ratings, though I'm morally sure they're at least 25A). I'm hoping that won't overload the input to the ECM, we'll see. I'll try the configuration this evening on my "testbed" (the new fan, a bunch of wires, and my giant battery charger) and get back to you.

[strotter]

Well, I just got back from the car, and the series relays work perfectly. A/C comes on with the coolant cool, shuts off correctly (no buzz). As it warms, the low fan comes on where I set it (more or less). With the low speed circuit disabled, high speed comes on at the right time. A/C on then off at any time causes no problems.

 

Happy happy joy joy!

 

I'll be looking for a heavier SPDT relay for the high speed, too.

 

Hey, that was easy! I love it when things go smoothy.

[deja]

Glad to hear its all working. Electrics can be a nightmare when you start using stuff not designed to work together.

 

For your high current try this one. Its fro the UK but he delivered quickly. http://cgi.ebay.com/CAR-BIKE-12V-70A-5PIN-CHANGEOVER-RELAY-SWITCH-waterproo_W0QQitemZ370082605529QQihZ024QQcategoryZ14932QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

 

Well, I just got back from the car, and the series relays work perfectly. A/C comes on with the coolant cool, shuts off correctly (no buzz). As it warms, the low fan comes on where I set it (more or less). With the low speed circuit disabled, high speed comes on at the right time. A/C on then off at any time causes no problems.

 

Happy happy joy joy!

 

I'll be looking for a heavier SPDT relay for the high speed, too.

 

Hey, that was easy! I love it when things go smoothy.

[Tanman280z]

Can anyone help me find a wiring diagram for the column on my 77 280z. The shop rewired it but forgot to mark the wires coming out of the ignition and column. They dont know what blinker wire goes to what side and so on. Anything will help at this point...thanks.

[deja]

I believe the common for the blinker is the Green wire, Left is Wht/Blk and right is Wht/Red.

I also believe the dimmer common is Blk, high is Wht/Red and low is Red/Blk.

 

Can anyone help me find a wiring diagram for the column on my 77 280z. The shop rewired it but forgot to mark the wires coming out of the ignition and column. They dont know what blinker wire goes to what side and so on. Anything will help at this point...thanks.

[sstallings]

Deja,

Took me a minute to roll out my '77 280Z wiring diagram that I had enlarged at Kinkos to 4 feet by about 9 feet, but I can confirm your colors for the high and low beam (dimmer) headlights. However, my diagram shows the blinker/parking lights as GW common, B ground, and GR left and GB right.

I hope that helps.

Steve

[deja]

DOH, totally misread my drawing. The colors I posted are the Camaro harness conversion colors. You are correct sir.

 

Deja,

Took me a minute to roll out my '77 280Z wiring diagram that I had enlarged at Kinkos to 4 feet by about 9 feet, but I can confirm your colors for the high and low beam (dimmer) headlights. However, my diagram shows the blinker/parking lights as GW common, B ground, and GR left and GB right.

I hope that helps.

Steve