PCM Diagnostics & Tuning - Help me identify this harness, 98 or 99+?
05-03-2012, 07:11 PM
Parting out a wrecked trans am, pretty sure the pcm was a 98 (I think), but am not 100% sure if this harness is a 98, or 99-02. Car had an 01 harness in it at one point, just not sure if thats what I got with the car, as previous owner had swapped things around several times.
I know the coolant temp sensor is different, but Im not sure which plug that is, as I have no coolant temp sensor to look at currently.
05-03-2012, 11:17 PM
I'm curious how you tell? Would this harness have worked with a 98 PCM?
05-03-2012, 11:18 PM
Weird, there was a reply here earlier now it's gone
05-04-2012, 12:12 AM
The coolant sensor and oil pressure sending unit are different. It's hard to tell because the harness is bunched up in the pic.
05-04-2012, 12:15 AM
Im going to take more pics
05-04-2012, 02:19 AM
I dont know which plugs are actually the oil pressure and coolant temp. Here are some more pics, whats weird is that three pronged one with the yellow outline looks melted, but has an identical looking one near it. All I know is everything worked in the car, just trying to figure out what is what here.
05-04-2012, 10:13 AM
i believe it is a 98 harness
05-04-2012, 08:45 PM
I just need some solid confirmation, dont want to sell somebody the wrong part. Any idea on the TWO yellow plugs?
05-05-2012, 02:41 AM
Its simple to tell by the coolant temp sender. You need to find the leg of the harness that has: coolant temp sensor plug (2 or 3 pin), alt turn on plug (4 prong flat with only one slot being used, one wire may be looped to another terminal of the same connector) and the driver 02 (black square 4 pin female plug). This branch will tell you. It branches off from the drivers side injectors (4x 2 pin connectors with metal retainers built in spaced about 3 inches apart) then it branches to the TB and lid (TPS, IAC, MAF and IAT) on that branch....then the final leg of that harness goes to what I described above. This should let you trace it easier.
EDIT: last picture, the leg with the braided ground wire built in.....that's the coolant temp sensor with the yellow rubber, first one on that last branch.
05-05-2012, 02:44 AM
Here is alternator plug
Going to take another pic
05-05-2012, 02:45 AM
Added an edit to my post above. It's right upstream of the alt plug.
05-05-2012, 02:49 AM
Some more pics, plugged the iat sensor in to give me a reference of what is going where. The only connectors I know off of the top of my heard are injectors, pcm, harness plugs that go into the kick panel in the car, the o2's, the iat, the alternator, and thats it.
It all makes sense on a car, but laying in front of me, Im confused as to how to tell if it's really a 98 or 99+
05-05-2012, 02:52 AM
Did you read my edit? Its the yellow rubbered plug just above that gold braided ground wire.
05-05-2012, 02:54 AM
Are there supposed to be TWO yellow plugs that look identical?
05-05-2012, 02:57 AM
Another pic, the two yellow similar looking plugs are here, as well as that small red wire that is near the alternator plug, not sure what is going on there
05-05-2012, 02:58 AM
The other yellow 3 pin is the TPS.
05-05-2012, 03:03 AM
They are both 3 wire, this all makes sense now, that one on the left it tps for sure, since I plugged in maf to get a better relation of how things sit on the car/motor.
Thanks for helping me get this mapped out, any idea whats going on with the alternator plug, and that small red wire thats going to nothing? Is that the stator wire?
05-05-2012, 03:09 AM
No clue. The ones I've seen only use one wire and sometimes two other pins are just looped to each other. The alt only needs one wire to turn on.
05-05-2012, 03:12 AM
Thats basically how it appears though, three of the grey wires are looped doing nothing