The 3800sc harness I wound up with is not totally the same as gmtuners schematics or any other schematic I can find online.

On C2 (clear):
-the A/C Request (pin 22 dark green) is completely missing.

On C1 (blue):
-the UART communication (pin 15 tan) to OBD pin 9 is completely missing.

There are many other differences as well.
Does anyone have any idea what harness this is from? Or what the correct diagram is? The computer/engine is from a 2000 Buick Park Avenue Ultra. The engine itself used to be in a 2001 Pontiac Bonneville SSEI (the trans is form the bonneville still). All the wiring harness diagrams for this car are exactly the same as schematics, but MY HARNESS IS DIFFERENT!

Any help appreciated.

------------------
Austin H.

The Tan OBD2 wire isn't used on the swap so don't worry about it. GM Tuners shows it but it has no function for the swap.

I'm guessing your donor car used the BCM (Body Control Module) to tell the PCM when A/C was requested. Thus the absence of the A/C request wire. You need to get your PCM flashed anyways and when it's flashed, it will be flashed with the data from a car that uses the A/C request control wire. So you will need it when done (assuming you are going to have AC) but no worry that it isn't on your donor harness.

Ryan Gick (GM Tuners) is in Fort Wayne. Have him flash your PCM.

[This message has been edited by phonedawgz (edited 12-03-2016).]

It appears I have an Internal Range PNP PRNDL switch on my transmission. I think that accounts for the differences in wiring.

I cannot find how to wire this internal range switch to my C500 connector. The external switch should have a 7-pin connector that can be wired up for starter. I do not know how to convert my internal to do the same thing.

Is it just a matter of taking the extra wires from the trans connector and hooking them to my c500?

A forum here about the problem:
http://www.grandprixforums....3fc8dedefbfff8966915

With the Fiero swap, you will need the external switch. The internal switch does not include the reverse lights or the starter safety wiring. If you really wanted to you could include these modules from your donor. but much easier is just to use the external switch and be done with it. Your tranny has the mounting bosses for the switch, you just need to bolt it on. Then run the starter wire and the reverse wires through it.

Then since you have the switch you can use either the internal or the external switch positions. Both work fine. Ryan (GM Tuners) shows them to the external switch so that would be the easier one to wire to.

The four pin connector wires all run to the PCM.

On the 7 pin
Pin G - Fat Yellow to C500 (Starter wire from the ignition switch)
Pin B - Dk. Blue to C500 (Switched power from the fuse box to run the back up lights)
Pin F - Lt. Green to C500 (Runs to the back up lights)
Pin E - Fat Purple to the starter solenoid
Pin D - Black or Black/White - Ground

You should have found a fat purple wire in your harness that ran to the starter. The fat yellow needs to be the same gauge. You need the back up switch and the connectors. The switch new is cheap on the internet if you look around a bit.

I do have new wire, terminals, and a yard close to my work for the 7 pin connector. I have lots of the used four pin connectors with tails hanging on my wall.

Hit me up if you need to.

I believe the 7-pin does not need to interface at all with the PCM. I wonder if I can bypass the 4-pin and leave those 4-pin inputs in my internal switch alone:

trans connector (IMS)
F BLK/WHT 771 Transmission Range Signal A
G YEL 772 Transmission Range Signal B
H GRY 773 Transmission Range Signal C
J WHT 776 Transmission Range Signal P

Why would I need to run these to the 4-pin if they are already interfaced with the PCM and the 7-pin is independent of PCM signals?

Thank you for the replies. I actually met Ryan at a car show over the summer and have been emailing him.

Alright. Most of the important stuff seems to be correct. There were 6 pins total plus the external IMS switch needed for the swap that weren't quite the same. Some more differences:

2000 Buick Park Avenue Ultra 3800sc with an 2001 Pontiac Bonneville Transmission 4t65e-HD (not sure if this is true... donor car has been swapped)
-Oil sensor was already a 3-pin; 3rd pin goes to C2-53
-Temp sensor was a 2-pin; need to convert to 3-pin
-Ignition (C1-19) is a white wire instead of pink (does this mean it's not ignition at all?)
-Hot Coolant Indicator Control (C1-75) is missing
-Charge Indicator Control/Low battery (C1-36) is missing
-Internal IMS trans neutral safety switch instead of external
-A/C request is absent (C1-22)
-Serial Data UART is absent (C1-15)

Are any of these alarming? Any idea what to do about coolant/battery? I think if the white wire on pin 19 is not ignition, it will be easy to find the new ignition pin.
Any idea where I can find the AlldataDIY or Mitchell's schematics?

Anyone have a 2000 Buick Park Avenue Ultra or 2001 Bonneville SSEI PCM pinout?

[This message has been edited by AustinH (edited 12-05-2016).]

do your self a large favour and have the PCM reprogrammed as a GTP and wire every thing to GTP diagrams, some cars use data lines for control of things like the AC and some need an extra ignition source as well as some use a different pin for the DLC, some have an out put pin for the coolant light where on some this is through data lines. send me an email address and I can email you the diagrams