I'm not exactly sure what has happened. I'm starting to rebuild a 3800 SC II wiring harness for my swap (3800 SC III w/ Series 2 electrical downgrade & Getrag). I went to gmtuners' wiring harness conversion website (http://www.gmtuners.com/files/index.htm). I got my ECU and wiring harness from FastFieros. Lloyd claimed it was a Series II GTP wiring harness. The wiring harness connector for the ECU does fit into the ECU. I have an ECU with the service number of 09361735. That leads me to this set of instructions: http://www.gmtuners.com/fil...o_L67_PCM_wiring.pdf

After about 2 minutes, I noticed something was wrong. The instructions say to delete/connect wires that I don't have and I have wires that aren't mentioned in the instructions. I looked through the instructions for other swaps, but none of them match any better.

Discrepancies:
(blue connector)
No wire 3, 15, 36, 39, 70, 71, and 75
Extra wires are 1, 10, and 80

(clear connector)
No wire 6, 8, 9, 21, and 36
Extra wires are 19, 29, 30, 76, and 79

Anyone have any idea what is going on?

------------------
1988 Fiero GT "Rolling Thunder"
Restoration Project
Soon to have 3800 SC III
"I'm a Rolling Thunder and a Pouring Rain... I'm coming on like a Hurricane - ACDC"

Not every wiring harness will have every feature. The diagram just covers all the pins so you know to what to do if that wire is there. Such as delete fuel level output. If you don't have a wire there, then your job is already done for you. Same as 70, 71. You will need to insert a pin into location 75 to control the hot light in the dash. Which ever car that the wiring harness came from, probably didn't have that hot light controlled by the ECU.

quote Originally posted by Rolling Thunder: Discrepancies: (blue connector) No wire 3, 15, 36, 39, 70, 71, and 75 Extra wires are 1, 10, and 80 (clear connector) No wire 6, 8, 9, 21, and 36 Extra wires are 19, 29, 30, 76, and 79 Anyone have any idea what is going on?

Blue
3= Fuel level output - Not needed
15= Serial Data - Should go to ALDL port
36= Charge indicator Control - Should go to Batt light on dash if running alt through PCM (c500 B3)
39= Fuel pump spped cntrl - Not needed
70= Theft fuel enable - Not needed if PCM has had VATS removed
71= Torque requested - Not needed

1= Auto trans Fluid temp sens - Not needed
10= MAP 5v reference - Pin C of MAP sensor
80= A/C pressure sens. ground - Not needed

Clear
6= Low oil level light - Not needed
8= Tach control - Not needed
9= Torque delivered - Not needed
21= Performance shift switch - Can be used with 4t65 trans, switch to ground
36= Chang oil soon light - Not Needed

19= Not used
29= Not used
30= EGR pintle - pin D of EGR if used
76= Not Used
79= Not Used

I cant answer why your harness has wires in odd places, but this is what/where they should be.

quote Originally posted by Jncomutt: Not every wiring harness will have every feature. The diagram just covers all the pins so you know to what to do if that wire is there. Such as delete fuel level output. If you don't have a wire there, then your job is already done for you. Same as 70, 71. You will need to insert a pin into location 75 to control the hot light in the dash. Which ever car that the wiring harness came from, probably didn't have that hot light controlled by the ECU.

X2...not all harnesses are the same and not all will have pins in every location.....Best thing to do it remove all the wiring from the connectors, roll them up then label them then start with bare connectors.

Is the harness a factory donor harness, or has it already been adapted for use in the Fiero ? If it is still factory it doesnt matter where wires are now, like said dissasemle it all and start over one connector at a time.

quote Originally posted by Mike Gonzalez: Is the harness a factory donor harness, or has it already been adapted for use in the Fiero ? If it is still factory it doesnt matter where wires are now, like said dissasemle it all and start over one connector at a time.

It is a factory harness that is un-modified.

You may need to find out what year/make/model of car and what engine/trans that car had that the harness you were sold came out of. Harnesses that came from 1998-02 W-body 3800 cars should have the wiring in pretty much the right locations for the instructions you are using, but there may be some minor differences.

IF you were sold a harness from a 1996-97 3800 car or any car that didn't have a 3800 engine in it, it will be much different. Wiring from 2003-05 3800 cars will be a little different as well.

Now I will tell you that if you follow my wiring instructions 1 line at a time and run each wire to where the instructions say to run it (sensor, device, or car connection as explained); you should be able to do this wiring conversion without much of a problem. May just take you longer to do since you are working with a donor harness that isn't 100% identical for what the instructions were made for.

-ryan

------------------
7+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

that is a harness out of a 97 buick regal I have the exact same one with the wires missing. I just started working on mine today. keep me posted. I have mitchell on demand 5 so if you need a wiring diagram let me know.

[This message has been edited by fierofan25 (edited 08-18-2010).]

Here's question #2. Lloyd at FastFieros told me that for my series II electronics downgrade, I need series II fuel injectors. I do notice that the plug is different between the two series. However, if I had the pigtails/connectors for the series III fuel injectors, could I splice them into the Series II electronics or would that not work?

So, either I need 6 series III injector pigtails or 6 series II injectors.

ive got a harness froma 97 bonnie 3800 NA to modify for my L32 nad i have some L67 freshly cleaned injectors to put in, ill be keeping an eye on this. was your computer for a SC'd motor?

quote Originally posted by americasfuture2k: ive got a harness froma 97 bonnie 3800 NA to modify for my L32 nad i have some L67 freshly cleaned injectors to put in, ill be keeping an eye on this. was your computer for a SC'd motor?

Yes, Lloyd at FastFieros said he tuned it for a supercharged engine and for a manual transmission.

You can use the S3 injectors with an S2 computer if you use the corresponding S3 injector clips.

Ok, I'm not fully understanding what I need to do (what's new). I'm not sure where all of these wires are supposed to go.

1. The big thick bunch of wires coming out the top of my firewall from the original ECU... Am I supposed to pull that out so wires can go to the clear/blue connectors for the S2 ECU?

2. How do all the wires get from the engine bay to the ECU inside the car?

3. Can I delete all of the wires going to the 4T65-E since I'm using the 282?

4. Are the transmission gear selector switch wires used with the 282 (Blue 68)?

5. Am I supposed to use the high speed fan relay (Blue 5)?

6. What is the boost control solenoid (Clear 77)?

Missing wires:
Clear 77
Blue 15, 36, 39, 59, 75

Different colored wires:
Blue 19 is purple, not pink
Blue 32 is gray, not red or white
Blue 55 is dark green with a white stripe, not just dark green

quote Originally posted by Rolling Thunder: Ok, I'm not fully understanding what I need to do (what's new). I'm not sure where all of these wires are supposed to go. 1. The big thick bunch of wires coming out the top of my firewall from the original ECU... Am I supposed to pull that out so wires can go to the clear/blue connectors for the S2 ECU? 2. How do all the wires get from the engine bay to the ECU inside the car? 3. Can I delete all of the wires going to the 4T65-E since I'm using the 282? 4. Are the transmission gear selector switch wires used with the 282 (Blue 68)? 5. Am I supposed to use the high speed fan relay (Blue 5)? 6. What is the boost control solenoid (Clear 77)?

1. You reuse some of those wires, and ignore some other un-used ones. You can heat up the glue and pass through new wires.
2. See #1. Re-do the bulkhead passthrough.
3. Yes.
4. No, as long as the PCM has been programmed to ignore the missing transmission.
5. You can use the high speed output if you have a 2-speed fan, but the low speed only controlling the fiero's fan relay works fine.
6. The boost control solenoid recirculates air around the blower when boost isn't needed. Also known as the boost bypass valve.

Clear 77 would be missing if your harness came off an L36 (NA) car instead of a L67 (SC) car. just re-use one of the wires you no longer need, and run it to the correct spot.

As far as colors, the function is more important than the color. Just make sure they go to the correct place.

------------------


Currently in the middle of my 88 + 3800NA swap

quote Originally posted by aaronkoch: 6. The boost control solenoid recirculates air around the blower when boost isn't needed. Also known as the boost bypass valve.

Is that in one of the 3 holes I plugged in the throttle body side of the supercharger?

Unsure, as mine is a Naturally Aspirated, but I would guess so. You don't need the BBV, many run without it.

quote Originally posted by Rolling Thunder: Is that in one of the 3 holes I plugged in the throttle body side of the supercharger?

EGR block off plate maybe?

So, once I get all the pins in the blue and clear connectors correct, I just have to feed it through the firewall? Then I just have to hook up the rest of the wires to the 203, 500, and relays and such?

I traced all of the wires that I either deleted per instructions or were in pins that were unused. Most of them went to expected places. Some did not. I had a black wire that was not on the instructions that traced back to the connector in the following picture. Does anyone know what this connector is for?




I also noticed that about a half dozen wires went to a few connectors including these in the following picture. If memory serves, this went to a fuse box. Am I right? What do I do with all the wires that are going to it since I have nothing to hook it up to?



The instructions also mention wiring up the OBD2 connector. I don't have one. Is that bad?

[This message has been edited by Rolling Thunder (edited 08-25-2010).]

bump

Unsure about the ground, but that connector looks like the Intake Air Temp connector.

------------------


Currently in the middle of my 88 + 3800NA swap

quote Originally posted by aaronkoch: Unsure about the ground, but that connector looks like the Intake Air Temp connector.

Are all black wires on the harness grounds? I found that several black ones with white stripes were grounds.

quote Originally posted by Rolling Thunder: Are all black wires on the harness grounds? I found that several black ones with white stripes were grounds.

No. For example, there is a black wire that is used for the cam sensor signal. So you need to check wiring and pinout diagrams to be sure. GM also used other color wires as grounds: org/blk and red/blk; depending on the circuit.

------------------
7+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

quote Originally posted by Darth Fiero: So you need to check wiring and pinout diagrams to be sure.

Where do I find these diagrams? (I'm going to guess Google)

i too would like a pinout

here: http://www.gmtuners.com/files/index.htm

The wiring instructions I've made for these conversions are basically pinouts for the PCM you are using.

quote Originally posted by Darth Fiero: here: http://www.gmtuners.com/files/index.htm The wiring instructions I've made for these conversions are basically pinouts for the PCM you are using.

Not what I meant. I've printed mine out and have scribbled all over it to figure out where I'm foggy.

What I need is the info that's not on the print out. Such as what to do with the extra connectors I'm not using (like the big one pictured above). I'd like to assume that I delete it all, but I'd prefer not to undelete what I don't understand.

I'm hoping to find a diagram of the stock harness so I can figure out what these extra connectors go to.

that big connector is the fuse box connector. there are usually 2 others with it. i dont know what to do with it.

quote Originally posted by Rolling Thunder: I traced all of the wires that I either deleted per instructions or were in pins that were unused. Most of them went to expected places. Some did not. I had a black wire that was not on the instructions that traced back to the connector in the following picture. Does anyone know what this connector is for? I also noticed that about a half dozen wires went to a few connectors including these in the following picture. If memory serves, this went to a fuse box. Am I right? What do I do with all the wires that are going to it since I have nothing to hook it up to? The instructions also mention wiring up the OBD2 connector. I don't have one. Is that bad?

1. That connector should be for a 3 pin sensor in the A/C line. It is a pressure sensor that tells the ECM when it's O.K. to turn on the air and kick up the idle. The Fiero doesn't have one, so if your keeping the A/C working I would suggest finding a chunk of line from a 3800 car with this sensor and having a shop retrofit the lines to the 3800 compressor. If memory serves it should have a black, gray, and red with blk stripe. If not tell me the colors, and I'll tell you what else it could be. I think I have the 3800's completely memorized...

2. The only way to tell if you need any of those wires in the fuse box connector is to trace them back and find out what they are for.

3. Yes you need an OBD2 connector. Wire in all the wires that the factory diagrams show for the 3800 computer, i.e. data (usually tan), power, grounds, etc.

The project you have taken on is very difficult if your not familiar with GM wiring in general. Hopefully between all of us on here we can get you through it.

~Cheers,

Chad

------------------


Intercooled SC3800 II/III mated to a Getrag. 19's with 13" Brakes on all 4 corners. 5 years Avionics & 15 years Car Electronics.

quote Originally posted by MOBILE: The project you have taken on is very difficult if your not familiar with GM wiring in general. Hopefully between all of us on here we can get you through it.

This has been my plan. Hopefully, this thread will spell things out for people like me in the future.

btw, what is the black wire for? Is it a ground? If not, where do I hook it up?

that could also be throttle position sensor , or 3 pin coolant sender .

They way I have been doing mine requires alot of multimeter work . If that is not cut off from the harness yet tone it out to find out what pin it goes too.

As for the black wire seeing as how its most likely some kinda of sensor connector my money is on a ground to ecm.

once you get the whole picture of what your doing in your head its alot easier to do. I cut off all connectors with a descent amount of wire left on. Then I pluged in all my connectors and started draping wire to the locations I needed. I would use the same color wire as the connector to keep it simple, route everything the way I wanted and tape the wires together. then pull it out of the car and I soldered mine all together, do what ever method you prefer.

I didnt use a GM ecm , but I did manage to get everything i need through the old firewall connector using the stock Fiero wires. I have one extra wire after everything is said and done.

good luck , it will get easier

-Kemp

quote Originally posted by Kemp3: that could also be throttle position sensor , or 3 pin coolant sender . -Kemp

Good Call. I forgot about that. The coolant sensor should have a black, yellow, and green wire. If it's a 3800 I think the TPS's were a flat 3 pin.

quote Originally posted by Kemp3: They way I have been doing mine requires alot of multimeter work . If that is not cut off from the harness yet tone it out to find out what pin it goes too. As for the black wire seeing as how its most likely some kinda of sensor connector my money is on a ground to ecm. -Kemp

Right again. Multimeter is your best friend. The 98-02 ECM's run almost all the sensor grounds back to a individual pin in the computer. The earlier ECM's grounded them all together or to a body ground.

Chad
------------------


Intercooled SC3800 II/III mated to a Getrag. 19's with 13" Brakes on all 4 corners. 5 years Avionics & 15 years Car Electronics.

[This message has been edited by MOBILE (edited 08-29-2010).]

what i did when i built my 7730 harness for the 3500, i used a DMM to test each individual wire/pin to its corresponding sensor/pin took a while, but everything was verified. made a check list of everything and checked it off as i went.

Get rid of that big bulkhead connector, you wont' need it. You only need to run the sensor as Darth has listed in his pin out. This is the reason a lot of people like to strip the entire harness and then only pin the items they choose to use.

quote Originally posted by MOBILE: The earlier ECM's grounded them all together or to a body ground.

I have never seen any case where any sensor ground would or should be connected to a body/chassis ground. You get a LOT of noise in the signals if you do this. DO NOT ground sensor grounds to anywhere but back at the PCM.

[This message has been edited by Jncomutt (edited 08-30-2010).]

quote Originally posted by Jncomutt: I have never seen any case where any sensor ground would or should be connected to a body/chassis ground. You get a LOT of noise in the signals if you do this. DO NOT ground sensor grounds to anywhere but back at the PCM.

What is grounded to chassis?

MAF, ICM, type stuff is chassis ground. Cam/crank, tps,etc is sensor ground.

Still wiring my 3800. A bit confused....what is the difference between the PCM ground and a Chasis ground?

Dont they all go to the same place?

(I wired my ICM ground to the chasis, should I have run it back to the PCM? I grounded that to the chasis.)

No, they don't go to the same place. A sensor ground is typically used for a referenced sensor, such as TPS that requires accurate voltage readings. They are typically 5v sensors and use 5v reference voltage, not 12v battery voltage. They also req the sensor ground at the pcm, not the chassis ground.

I've started working on this again, so I have more questions.

What do the wires from the Getrag 282 connect to?

I plan to take some pictures of connectors and "loose ends" tomorrow to solve smaller problems.

bump