correction:

C203/L connects to Caddy E13 (not C203/B).

ALDL port G goes to fuel pump relay TAN/WHT (not E13).

*** for those that wish to use the Caddy cruise control:

from Fiero cruise module connector to Caddy ECM

A to D2
G to C2
L to D3
M to C3
K to F3
C to F2
H to B4
F to B3

A/C if your car has A/C it has to be wired as a stand alone unit - the Caddy A/C electrical is not compatiable with the Fieros A/C electrical. There is an older thread on here someplace that talks about it.

[This message has been edited by Mickey_Moose (edited 12-29-2006).]

Thanks for the corrections, I've edited my previous post to reflect those changes.

Here's the schematic for the A/C that I got from Al Davis:



Here's the diagram for the alterations to the caddy tranmission (lockup torque) control circuit (pretty simple, I think) Tap the P (C203) pin purple wire into the purple wire that comes out of PCM C4 (also a purple wire) and run the pnk black out of the converter lockup connector to the F pin of C203. Basically what the circuit does is unlock the torque converter whenever the brake is applied.

[This message has been edited by Brian Lamberts (edited 12-28-2006).]

Hopefully the schematics are helpful but bear in mind I made these while away from my computer and my car during a 6 month deployment to the Persian Gulf. Not everything will work as I thought but I think it is somewhat close. The AC and the fuel pump relays are two of the sections I had the hardest time with since a lot of it had to be changed or modified. Just let me know where I screwed up and I can modify the drawings as needed.
Al

Reguarding the cruise control - you can leave the factory Fiero cruise as it is and not have to worry about the extra wiring. I just did it that way, just because that is the way I am.

The factory cruise will work just fine without any modifications.

quote Originally posted by Brian Lamberts: Thanks for the corrections, I've edited my previous post to reflect those changes. Here's the schematic for the A/C that I got from Al Davis:

I haven't looked in depth at the other circuits, but this one won't work so well. In normal operation, the ECM supplies the ground for the primary side of the relay. When you put your foot down far enough to get into power enrichment, the ECM uses this to deenergize the relay which turns off the compressor.

The way you have it wired, the compressor would stay on at WOT all the way to redline.

Instead of grounding that wire, run it to PCM pin 3F4.

quote Originally posted by Will: Instead of grounding that wire, run it to PCM pin 3F4.

Nice catch Will, please review the rest of it and add suggestions/comments/corrections. (Thanks!)

The connection Will is referring to is on the Green Large ecm F3, the wire color is green with a black trace. It originally (on the Caddy) ran towards the dash, so there's just a length of wire coming out of the PCM for this--it doesn't feed up throught the C225. I'll need to run a length of wire from this spot on the PCM to the dark blue wire on the A/C relay.

quote Originally posted by Mickey Moose: Regarding the cruise control - you can leave the factory Fiero cruise as it is and not have to worry about the extra wiring. I just did it that way, just because that is the way I am.

Yeah, it appeared that way to me, too. The car I'm putting this into has no cruise control present (it's an 88 base coupe) and cruise isn't important enough for me to get too worried about it. I've included the material you and Al provided incase someone else is interested.

I'm pretty happy with the way this is going--I think we're getting there on having a way to diy this thing.

[This message has been edited by Brian Lamberts (edited 12-28-2006).]

If your saying to yourself that this seems easy, then your well more than half way done with the project.

quote Originally posted by Brian Lamberts: The ALDL that came with my caddy stuff has no tan/white wire and nothing in the port G. I've edited the big wiring post on page one of this thread so that the ALDL purple wire at pos. K connects to the fuel pump relay power circuit--Pin L on the C203 tan/white wire.

You have to wire the ALDL port as the diagram otherwise you will not get a scan tool to work - trust me on this one, not sure why and not about to figure it out either as I found something that does work (others have found the same). You can simply remove the connector and install it into the correct location. My wiring notes work 100% as shown, not just on one swap but several (never done one with A/C so I am of no real help there).

BTW - you should NEVER completely rely on wire colors - colors fade, sometimes different year use different colors, etc - always verify pin locations.

I haven't started making the connections, I need to go find an PCM (today) and get the pcm harness laid out in the car before I can start. But I will take your advice about verifying locations--thanks.

And I'll reposition that purple wire in the aldl connector as you suggest.

I'm looking at Capt Fiero's suggestions about triggering the cooling fan through the PCM

https://www.fiero.nl/forum/Forum2/HTML/078713.html

quote Originally posted by Brian Lamberts: I'm looking at Capt Fiero's suggestions about triggering the cooling fan through the PCM https://www.fiero.nl/forum/Forum2/HTML/078713.html

Yea, I have read this I think it is interesting - but don't think that it is necessary. I drive my car all year round and have found that it is warm enough during the winter and I have been driving without a passenger interior door panel on the car during -25 C weather while I do some work on it. Granted if there was a passenger, they might have found it cool.

I run a 190 thermostat all year and see absolutly no point in changing a thermostat in a car that is ECM controlled - after all it was designed to work that way. But then, that is just me - I find that changing it is old school (as is all those people that put cardboard to cover up the rad on a new car)

[This message has been edited by Mickey_Moose (edited 12-30-2006).]

Did something dumb last night. I was working on shortening the PCM harness and started on the wires that go to the green connector. Snip, snip, snip, snip! THEN I noticed that there wer 4 blue wires (all the same blue, too) and 4 green wires, all the same, to reconnect. UH OH! Well, I have enough stuff about where wires are supposed to run to figure it out, but it took time and was pretty scary for a while.

Take it as a cautionary tale--the use the same color wires for totally different thing in the same connector sets.

quote Originally posted by Brian Lamberts: Did something dumb last night. I was working on shortening the PCM harness and started on the wires that go to the green connector. Snip, snip, snip, snip! THEN I noticed that there wer 4 blue wires (all the same blue, too) and 4 green wires, all the same, to reconnect. UH OH! Well, I have enough stuff about where wires are supposed to run to figure it out, but it took time and was pretty scary for a while. Take it as a cautionary tale--the use the same color wires for totally different thing in the same connector sets.

Good you got it all figured out, but that is why I always pull the harness apart and label each group of wires at the ECM side as to what the other end connects to - that way no worries

I found a couple of guys (forum members) who burn proms. $90, one of the guys provides a new chip, the other doesn't. I don't have permission to post the names of these guys, so if someone is needing to have a prom burned PM me and I'll put the guys in touch.

Some random stuff about the proms. One of the guys I've been emailing says that if I use the 91 Deville exhaust manifolds--that's a two O2 sensor system--he can change the maps on the programming so that I can get an additional 20 hp and 15 lb if torque. If I can find a 91 in the yard I'm gonna do this. The wiring change looks pretty straightforward.

The main reason to do the prom reprogramming is to turn off some of the PCM functions that are not needed on the FIero--and would set off the SES light on the dash. And to turn off the Caddy's antitheft circuit--I have mixed thoughts about this, it would be nice to be able to put a switch in to activate the antitheft circuit and disable the fuel injectors. Rockcrawl has been selling a small circuit to disable the antitheft.

quote Originally posted by Brian Lamberts: Some random stuff about the proms. One of the guys I've been emailing says that if I use the 91 Deville exhaust manifolds--that's a two O2 sensor system--he can change the maps on the programming so that I can get an additional 20 hp and 15 lb if torque. If I can find a 91 in the yard I'm gonna do this. The wiring change looks pretty straightforward. The main reason to do the prom reprogramming is to turn off some of the PCM functions that are not needed on the FIero--and would set off the SES light on the dash. And to turn off the Caddy's antitheft circuit--I have mixed thoughts about this, it would be nice to be able to put a switch in to activate the antitheft circuit and disable the fuel injectors. Rockcrawl has been selling a small circuit to disable the antitheft.

Hmmm, first I heard about adding a 2nd O2 sensor will give you 20hp (with programming). I like to hear the logic behind this as to why the fuel maps can not be used with a single O2 setup.

The MEMCAL programming also needs the speed multiplier changed if you are using the standard tranny (as well as the idle target). Other things that you may want to change are the speed and rev limiters.

I myself prefer to keep the Passkey system activated and will be used at a later date in my own car as I finish off the interior. Right now I am just activating the bypass module at key on, but in the future it will be activated by a RFID tag.

Here's the table with the pinouts for the C203. If it's too difficult to read, I can email a copy on request.

quote Originally posted by Will: I haven't looked in depth at the other circuits, but this one won't work so well. In normal operation, the ECM supplies the ground for the primary side of the relay. When you put your foot down far enough to get into power enrichment, the ECM uses this to deenergize the relay which turns off the compressor. The way you have it wired, the compressor would stay on at WOT all the way to redline. Instead of grounding that wire, run it to PCM pin 3F4.

The Caddy PCM grounds the 3F4 connection to do all the cycling of the A/C compressor not just turning off the comnpresor at WOT. There is no pressure switch in the Caddy system. The BCM receives information from refrigerant pressure and temperature sensors and in turns sends information to the PCM. Based on this information the PCM opens and closes the 3F4 connection to operate the A/C relay and cycle the A/C compressor This information from the BCM is absent in a Fiero swap. Whether or not what Will is suggesting works, depends on whether the 3F4 contact is open or closed in the absence of the BCM data. My hunch is that this contact is normally open so that absent the BCM data the A/C does not run.

FWIW, my '95 Deville/Eldorado/Seville manual indicates that 3F4 is normally grounded.

Ok, everything EXCEPT the A/C is making sense. Does anyone have a wiring harness that is in a working car, that has the A/C working with a Cad ecm? Are we all just planning this out on paper, or does any one actually have the working answer to this. It all seems to make sense for a second, then someone else will bring up something that seems like it won't work. This is getting to be a pain.

Thanks for all the info so far. I will help as I can. I have hopes to be turning the engine over by mid March. If I do and there are still questions, I will try to answer what worked for me.

thanks again,
Darren

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I haven't even started to think about the A/C. I think I can figure it out--when I start to think about that part. THere's a guy over in Redding that can help me figure out the final A/C wiring. & I think that I need to look at the pinouts for the Fiero ECM.

And this is kinda being planned out on paper and slowly getting soldered together.

I don't have any space to bring the car in for the start of the swap, yet. so the cab portion of the harness is coming along, but won't be tested 'til about April. The engine bay part is mostly pretty easy. Some of the wiring for the A/C comes in through C500.

The other factor is that the tags on the car are up in April, I can't get the next smog 'til the tags need renewal--and the idea is to get the reg. renewed and then immediately bring the car in for the swap. Gives me a whole year to get it sorted before smog time comes up again.

In the meantime, the harness and tracking down other parts is what I'm doing. (BTW, Partsamerica sells trannie mounts for $4.19)

quote Originally posted by Will: FWIW, my '95 Deville/Eldorado/Seville manual indicates that 3F4 is normally grounded.

This would be good news as it would be nice if the A/C turned off at WOT. I have a 92 Helms manual and compressor controls schematic seems to indicate normally open. Ultimately the only way to tell is to test it. I'll do this but it will be a couple of weeks before I get back to the project. My hobby shop is at our weekend property 190 miles away.

In a previous thread we reverse engineered the Ed Parks harness and the A/C is wired up totally independent of the PCM i.e. the relay coil just goes to ground

This is from Alldata (disregard the MT at the top, that's part of another circuit.)



It looks to me like the dark blue wire out of the relay would go to PCM F4 which is a Green/black wire. (which is what Will said.)

The light blue wire (which on a Fiero goes to the ECM) would only go to the relay from C203 pin D. There's no provision for A/C Request signal on the 4.9 PCM.

I assume that fan control (fan comes on when you turn the A/C on remember) is part of the dash wiring. Confirmed!

The black wire out of the relay is the power supply and would go to N on the C203 also black.

The only other wire out of the relay is the green wire that goes to the C500 part of the A/C compressor wiring.

One other thing, the Caddy a/c turns off when the power steering is used for parking, there's a switch I believe in the power steering that cuts the a/c through the PCM. I've read so much, I don't know where I read it, but the power steering switch output on the PCM needs to be grounded. (Or if the A/C doesn't work, it need to be ungrounded.) It shouldn't be connected to a hot wire, tho. PCM C9 Lt blu/orange connects to C203 pin F. Note: Mickey Moose says: "power steering ECM input has to be connected to +12v"--so I don't know about this.

[This message has been edited by Brian Lamberts (edited 01-15-2007).]

More stuff. I got this from forum member Al Davis--he deserves ALL the credit, I made a few alterations, but he did all the hard work.

The C9 power steering line that you have grounded I found the +12V reference in thread https://www.fiero.nl/forum/A...031110-2-037993.html Rockcrawl mentioned that it needed to be tied high for evrything to run correctly and the closest place was F of C203. If low is the way it should be then chassis ground as you show now should be fine.

Powersteering switch. I did a little more looking and it does appear that applying a 12v feed to this connection is the way to go. So instead of grounding, connect it to c203 F

quote Originally posted by sanderson: In a previous thread we reverse engineered the Ed Parks harness and the A/C is wired up totally independent of the PCM i.e. the relay coil just goes to ground

quote Originally posted by Brian Lamberts: More stuff. I got this from forum member Al Davis--he deserves ALL the credit, I made a few alterations, but he did all the hard work.

I guess I'm the only one who cares about overspeeding A/C compressors.

Did Ed Parks at least advise customers to turn off the A/C before matting the gas?

[This message has been edited by Will (edited 01-15-2007).]

quote Originally posted by Will: I guess I'm the only one who cares about overspeeding A/C compressors. Did Ed Parks at least advise customers to turn off the A/C before matting the gas?

Maybe it's not a reliability problem to spin the compressor up to redline. But if you're GM looking for max power and have a computer, it's so easy to turn the compressor off at WOT and gain a couple of HP. Anybody know what they did back in the 60's before computer control came around?

quote Originally posted by sanderson: Maybe it's not a reliability problem to spin the compressor up to redline. But if you're GM looking for max power and have a computer, it's so easy to turn the compressor off at WOT and gain a couple of HP. Anybody know what they did back in the 60's before computer control came around?

SS396 or 454 etc., Mopar 383or 440, Ford 427 or 460? The A/C on my old 63 Newport (361 big block) was pretty much turn the a/c on and let her run til the car was too cold to tolerated. Chrysler used to use massive A/C, btw.

I don't think it's as big a deal as Will does, but if the computer can do it it would be a nice feature. Funny that someone hasn't piped up with a definitive answer--folks have been doint this swap for at least 10 years now.

quote Originally posted by Brian Lamberts: SS396 or 454 etc., Mopar 383or 440, Ford 427 or 460? The A/C on my old 63 Newport (361 big block) was pretty much turn the a/c on and let her run til the car was too cold to tolerated. Chrysler used to use massive A/C, btw.

I was wondering if they turned the A/C compressor off with a manifold vacuum switch or throttle linkage switch or something like that.

My 65 Thunderbird and 66 Mustang do not have any provision to turn off the AC based on throttle position. Neither did my 72 Catalina (455). If it is a major concern and the ECM does not have the provision for it, just put a NC switch into the compressor control circuit and locate the switch so it opens when you floor the gas. Should be a very short run of wire.

quote Originally posted by Brian Lamberts: So to Mr. Moose up in Edmonton, Will, and the rest of yuz, keep it up! And thanks.

I have posted all the info I have/you should need.

I have personally not yet done an a/c car, but have looked into it: there is no way to control the a/c unit with the Caddy ECM when wired as a 91 DeVille. It needs to be manually controlled. GM controls it through a different module, which feeds the data to the ECM via 3E, so unless you add this module in, forget about trying to get the ECM to control it. However, feel free to explore this aspect yourself if you wish, but only post what does work, not what you think will work so as not to confuse the new people trying to do this with all the different methods.

FYI >> you people need to stop looking at all the different diagrams that are out there, the wiring is different for the different models and years. Everything that Rockcrawl, PBJ and myself have done is based on the 91 DeVille diagrams ONLY. The 91 DeVille diagrams work for all years and makes (have done: 91 DeVille, 92 SeVille, 93 Fleetwood (x2) and the 94 DeVille using the 91 diagrams and all cars are running (the 94 DeVille MEMCAL is not compatiable with the 91 code and needs to be replaced with an earlier one). All the diagrams are on Rockcrawls website. But hey, if you rather go back and forth between all the diagrams, knock yourselves out - you are only making it harder than it really is.

Well, I got a little further on mine today. How is everyone else coming along? I was able to almost figure out all of the c500 stuff. I came on here to tie up a few things I was wondering about and saw that this thread had gone to sleep for too long, so this is a bump, so that it doesn't get forgotten. I am hoping to have mine turning over by spring, so I'm not in to big a hurry, but will try to take some pictures as I go along. Thanks for all the help that every one has been so far. Still not looking forward to the A/C. I am reading up a lot on what the best way it would be to make it work, and am more confused than ever. oh well, maybe someone will turn there's over before I do and tell me what they did to make it all work.

Talk at you guys soon,
Darren

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I have a parts car in the garage and can't hardly get to my 4.9 engine. When the part car is gone, I have a Formula to paint, when that's done (probably in late march) the 88 base coupe will come in for an engine transplant.

I don't think the A/C wiring is too critical. Main thing is to get the engine in and running--and as Mickey Moose (I knew his name but forgot it) said--everything you need is here in the thread. Even the C500 stuff--just figure it out.

Hey Brian,

If you have any pages that are not listed on here, can you email what ever you have? dpdonk@sbcglobal.net Thanks in advance. I think I might pull out some wiring tonight and see if I can get a little further. This thread is really nice to have. Just wish the Oklahoma weather was a little nice so I could get outside and work on the engine bay, and get to pull a part. But with the wind chill it's like 10 degrees.

Thanks again in advance.

Darren

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I didn't remove the harness myself so this might seem like a dumb question.

The connection block for the Caddy harness that has the screw through it -- Did that actually connect to something else or is it just a way to connect all wires that are in the block itself. Basically, does it connect to something or are they all terminal connections?

I'm expecting this to be the hardest part of the swap. Once of my friends that wires race cars is helping me out. Like everyone else I'm grateful for the help with this.

[This message has been edited by vafierro (edited 02-25-2007).]

quote Originally posted by vafierro: The connection block for the Caddy harness that has the screw through it -- Did that actually connect to something else or is it just a way to connect all wires that are in the block itself. Basically, does it connect to something or are they all terminal connections?

Yes, to connected to another block which in turn connects to the plugs for the ECM. The plug normally is what passes through the firewall (1/2 on either side) - basically a quick disconnect for the motor.

quote Originally posted by Brian Lamberts: Finally when I speak of the strain reliever--this is what I'm speaking of. This is the connection block of the engine harness, and to the right of the block is the part that goes through the rear bulkhead. I removed the caddy strain reliever and put the Fiero one in. The Caddy one I mangled pretty well getting it off--it's put together with black goop on the engine side and then this resin material inside the plastic outer pieces. There's a trick to getting the resin goop out and off the the wire and the internal loom. You need to freeze the wiring harness and then smack the clear stuff with a hammer to shatter it, then pick the remainders out so that the wiring can fit in Fiero specific part.

Someone else pulled the wiring harness for me. I did not get the block that this plugs in to. I do however have the rest of the harness, and the computer. It appears that all the sensor connections as well as the ECU connections are intact, but I'm wondering what this connector is for and if I'm missing something.