I will be wiring up the 203 and 500 connections today. I counted 11 connections to the 203 (4 of which connect to pin K) making it 8 pins used on the 203 plug in the car and 4 connections to the 500 plug by the battery.

I have 2 of the wires labled for the 500 plug, Low fan speed control and Engine hot warning lamp, but I have no idea where the other 2 wires should be coming from.
The ICM power input and the ICM Tach Signal

They were wired into the 2.8 harness but no idea where they went to. Im guessing one of them is the large purple wire for the power input maybe?

Thanks Steve

The large purple wire is for the starter.

Look at this site for all the pinouts of the C500 and C203
http://www.fieroaddiction.com/c203c500.html

Matt

Ok, Thanks. That helps a bit. Both wires run from the c500 to the coil pack on the 3800. Just need to figure out which wires they are.

Steve

Edit: Sorry but I may have alot of questions today in this thread.

The 500 has the large red wire running to the alt (bolts on). Its not mentioned in the pinouts so do I just remove it with the 500 plug and connect it to the 3800 alt?

[This message has been edited by JumpStart (edited 01-23-2011).]

Two wires from C500 to the ICM are 12v power (pink), and Tachometer feed (white). Not sure if that is what you are needing to know though. Every wire on the c500 connector should be used. a few on c203 will be abandoned when the harness is done.

[This message has been edited by Mike Gonzalez (edited 01-23-2011).]

quote Originally posted by JumpStart: The 500 has the large red wire running to the alt (bolts on). Its not mentioned in the pinouts so do I just remove it with the 500 plug and connect it to the 3800 alt?

Whoa..... slow down. The large red wire that runs from the alternator goes to the power distribution block, which is underneath the c500. You'll want to run a large gauge wire from the alternator/starter to the power distribution still, but it shouldn't connect to any part of the control wiring.

The "ICM power intput" is the coil power feed pin E3 (pink), and the tachometer feed is pin C3 (white).



For a 3800 swap, you should ground A2, A4 would go to your neutral safety switch if your car is an automatic, B3 is the alternator charge gauge, if a manual transmission the purple wire E2 goes straight to the starter solenoid, backup lights are C1 and E1 if not using a 4 speed, C2 is the temperature gauge feed, D1 is the only fan speed wire you should use and it should be controlled by the PCM feed (don't use low speed fan request), D3 is the "engine hot" light.

[This message has been edited by L67 (edited 01-23-2011).]

Thanks....That pinout may help alot.

I will go ahead and post this incase I still do not understand what I am looking at and maybe get it by process of elimanation lol

First off I have an 86 manual V6....

My C500 plug has only 9 wires and the pinout seem to ask for more than 9 connections.

This is what I have now



Its a manual so no Yellow wire there (A4)

The 2 green wires together are in question ( think they came from a single plug)

The other green wire has an ilet on it with 1 black wire going nowhere now(looks like a ground to me)

Thanks for the patience ,

Steve

What is your best guess as to where the green wires come from?

You can use your ohm meter to make sure you have the correct pin to the wire.

Looking at the pinout L67 posted and comparing it to my engine harness connector, I have no pins for A1,A4 or D2. This came from a running 2.8.

Steve

quote Originally posted by JumpStart: My C500 plug has only 9 wires and the pinout seem to ask for more than 9 connections. The 2 green wires together are in question ( think they came from a single plug) The other green wire has an ilet on it with 1 black wire going nowhere now(looks like a ground to me) Thanks for the patience , Steve

You won't be using A1 or A4. Your backup lamp switch is probably on your 4 speed shifter, so scratch the backup lamp feeds (C1 and E1). You'll only need the single fan control (D1). That leaves 8 wires. Your 9th wire is the second fan control - axe it.

The two green wires look like the ends of the coolant temperature gauge, but if there's a white stripe running down the wire on top, it's the fan switch circuit. The wires with the ilet are both grounds, one should be A2 the other is a sensor ground.

When I build harness, I cut the C500 off completely with about a foot of wire. From there you can start fresh, and attach the C500 to your newly fabricated 3800 harness.

[This message has been edited by L67 (edited 01-23-2011).]

A1 and A4 say that it is the Trunk release and starter. Am I looking at something wrong?

Steve

Edit: Ok..A4 is auto only

[This message has been edited by JumpStart (edited 01-23-2011).]

The starter wire is on one of two pins depending if its a manual or auto. That's why the pin is open You have manual so the AUTO starter pin is unused

The trunk release doesn't run through the engine harness - that is why that one is unused

This pinout has more detail

[This message has been edited by phonedawgz (edited 01-23-2011).]

A1 is designated for trunk release, but in the two dozen harnesses I've pulled apart, I've never once seen the trunk release circuitry come through the C500. I think it might be an open loop for a manual bypass from the factory. Ignore A1 forever on.

A4 is the yellow energizer wire for the neutral safety on an automatic transmission. If your swap will be using a manual transmission, you'll run E2 directly to the starter solenoid.

Phonedawg:
Use this version, it's a little bit friendlier.

http://img199.imageshack.us/img199/4899/c203.jpg

[This message has been edited by L67 (edited 01-23-2011).]

Thanks... Im ahead of the game now lol

Out to see what I can get done.

Steve

I'm not sure what you are saying. It WAS wired for both the console switch and the tranny switch? Yes you need to connect wires from those two terminals to the switch on the tranny. When the tranny switch is closed (tranny in reverse) power will flow from the source, through the switch, and then to the reverse lights making them come on.

It's ok that there is a switch connector also at the console but not connected to anything.

Yes the wires for the reverse switch is already to the body side of C500 so you now only need to extend them on the engine side of C500.

[This message has been edited by phonedawgz (edited 01-23-2011).]

Yes, if you connect the Getrag or Isuzu reverse feeds to C1 and E1, the reverse lights will work. I installed a 3800 with a 5 speed Getrag into an 86 GT just like yours; originally a 4 speed with the switch on the shifter. Plugging the switch into the C500 worked without flaw. It was nice of GM to make the Fiero somewhat reverse compatible.

Take notes. good notes! wright it down. put them in the computer. down the road their will be a test.

quote Originally posted by FFIEROFRED: Take notes. good notes! wright it down. put them in the computer. down the road their will be a test.

And he ain't kidding either

quote Originally posted by FFIEROFRED: Take notes. good notes! wright it down. put them in the computer. down the road their will be a test.

Im sure of that lol

I did get some wiring done and realized that some of the wires I labeled, Im still not sure where to wire them to..

Example: GMTunners pinout says clear pin 3 connects to pin A for the fuelpump relay. I know the wires for the fuel pump come up to a plug then into the cabin with the wiring harness on the passenger side but where do I wire in the clear pin 3 wire at?

Thanks Steve

C3 is the relay control from the PCM. You wire it into pin A of the relay like you stated. The relay is on the firewall, to the left of the bulkhead connectors. There are two; one is AC, the other is fuel pump.

ok...Ill look into it. Thanks

Steve

What year PCM are you wiring for ?

I was told it was a 98 engine and also I was told that if I were to get a PCM from a 98 S/C car, that it should start up and run without programming anything (yes it will need to be tuned but atleast I could move the car)

Steve

Sent you a email !

Edit: oops, your Email addy didnt work, PM me a good Email !

[This message has been edited by Mike Gonzalez (edited 01-24-2011).]

I agree with Mike.

Sent you a PM Mike.

Thanks everyone for your help on this.

Steve

A relay is an electrically controlled switch. On the stock 2.8 wiring harness there are two relays next to the air cleaner housing. One is for the AC, the other the fuel pump. The relay plugs into the base (connector) on the wiring harness.

GM used a relay so the high power needed by the fuel pump doesn't run through the ECM and kill the ECM if a trouble occurs.

The fuel pump relay base is the one with the following color wires - Black (Ground) - Tan (Power TO fuel pump) - Orange/Black (Power from fuse box) - and Dark Green White (Control wire which get's it's signal from the ECM)

So the wire marked Fuel Relay - or Fuel Control - connects to the Dark Green White of that relay base.

======================

The two wire connector with the wires TAN and BLACK/RED is the Manifold Air Temperature sensor. Yes it is NOT located in the Manifold. It is also called Air Charge Temp sensor or Intake Air Temperature. ACT or IAT. Three names for the same sensor. The BLACK/RED connects to a ground port on the ECM. The TAN connects to the Air Temperature Input or like that. Note - the reason the ground connects to a ground port on the ECM is to prevent issues with bad grounding issues from messing up the operation of the engine.

[This message has been edited by phonedawgz (edited 01-24-2011).]

For you:



I wanted to be sure the ground of the control side of the relay didn't need to return to the computer like it does with the '94-'95 computers. Looks like the '98 computer is pretty straight forward.

Your description of the relays sounds correct. They look like this:

[This message has been edited by L67 (edited 01-24-2011).]

Ok...Thanks for the info and the pinout Mike sent me made a world of difference. It now makes ALOT more sense.

Ill keep ya posted the next few days and thank you again

Steve

If it was truly helpful, one of you should post it.

Don't be afraid to ask question. How are you doing your splices? Soldered? Shrink tube over the solder joint?

quote Originally posted by L67: If it was truly helpful, one of you should post it.

It is my wiring spreadsheet, it is an .xls, but give me a few and I will screenshot it and post it.

I would post it but it is in xls format. Maybe he could post it up.

quote Originally posted by phonedawgz: Don't be afraid to ask question. How are you doing your splices? Soldered? Shrink tube over the solder joint?

I soldered alot of them but for the 203 and 500 I have just been using crimp sleeves.The location of the car is not the best place to do a swap(no room AND with an 88 right next to it in the shed) so I just want to get it wired correctly and running so I can get it moved. After I am satisfied that everything is working like it should, I plan on pulling out the drive train again and touching up on a few things including the harness.

I know this is not the best way to do it but it is the only swap I have done and I hate to spend alot of time on making things really neat when I might just be tearing into it again because of mistakes.

Steve

oops.

[This message has been edited by L67 (edited 01-24-2011).]

Here Ya Go !

Very good of you to post that, I'm sure it will help quiet a few first timers.

No prob ! It didnt come out quite as clear as a .jpg, but its legible anyway ! It still helps me out !

It is based on GMtuners (Ryans) Wiring instructions, but I just made it an easier to follow layout for myself, and added all the additional connections that need to be included in the harness.

Organization makes all the difference in the world.