OK, I put an 87 ECM and harness in my 85 TPI IROC, won't start.
Need some help w/wiring,
87 harness to ECM has 2 connectors that go to ECM, also seperate strand of wires w/ clear conn. that has 2 rows of 8 pins lettered a-h,i-p?

The 85 harness to ECM has 2 conn. to ECM, also 2 seperate strands, 1 w/same clear conn. as 87, and the other to a small gray conn. that plugged into the piggy back module on the 85 ECM.

I know the MAS from the 85 isn't needed for the 87, but what do I do w/ the plug just hanging there w/ 2 pink/blk IGN 12v wires and 1 brn/blk wire? Aren't the pink ones from the INJ fuses, and if so where does the 87 setup get its power for the inj.?

Also the clear plug w/2 rows of 8, most of the wires match in color, but a few are wrong, like the two black wires that are coming from the injectors on the 87 setup. They are now connected to a red/blk and pink/blk. This can't be right!
I was told that I could put the 87 setup in place of the 85 w/o these problems, I knew better, nothing is ever easy if someone tells you, oh yeah, it will hook right up!
Anyway if someone else has successfully done this before, PLEASE let me know if there are certain wires I need to move around on the clear plug to the harness under the pass. side dash?

Another thing is the fuel pump only runs if I hot wire it, worked fine with the 85 system! Term. G on the ALDL conn. won't even power it up.

 

I had the same trouble when i did my engine swap earlier this year. I had to buy an aftermarket harness, well i didn't have to, but i plugged it in, and it fired right up

PM a guy named trickster, he will have the wiring diagrams you need.

 

Are you sure the 87 harness wasn't messed with? I upgraded my 85 with an 87 harness and a 165 ECM. I ran into no problems. Had I kept my original distributer, the distributer plugs would have had to been modified, but that would have been it. This is really a plug and play type of deal.

 

As far as I can tell nothing has been messed with on the 87 harness. Can you tell me what color the wires are on the clear plug I am talking about? What about the pink/blk wires that ran 12v to the 85 injector harness? Also read some where that 85 injector harness has only 1 ground not 2? I guess I'll give TRICKSTER a try.

Thanks and any other help would be greatly appreciated, I'm starting to go
Doug

 

I don't remember having a clear plug. What did it plug into?

 

The clear plug would be the Instrument Panel connector on the right side of the dash.
It has power to the ECM, Injectors, ESC connections, brake switch for TCC, and others. You will need a schematic of the exact car to find what each does, but there are some important ones there.

 

Yeah thats the one, hey Jim do you have any info that might help me?
Or anyone?

 

This thread may help.
https://www.thirdgen.org/techbb2/sho...%2FP+connector

There are a few others that have pinouts forthe I/P connector but I didn't see them in my 2 sec search.
Check the search with different terminology, it's there (I've seen it)
Good luck.

 

I/P connector? Thanks I'll do some searchin'

 

I don't know what to tell you. All of my under-dash wiring plugged right into the 165 ECM with absolutely no modifications necessary. Either your wiring is hacked, or your computer is FUBARd.

 

Everything plugged in just fine, the only thing is the wires in the 85 16pin i/p connector coming from the dash don't all match the wires in the 87 harness, and the 85 has the small 6pin square plug w/the pink/blk wires to the inj. fuses on the fuse block and the 87 harness doesn't have the plug, the wires for the inj. 12v are in the 16pin i/p connector plug coming from the engine/ecm harness. also the small orange wire from the f/p relay that is supposed to go to term g on the ALDL conn goes to the bulkhead on the d.side behind fuse block into an empty port. This is the second ecm.

 

Did you replace all of the 85 wiring harness with the 87 harness or are you still running some of the 85 harness inside the car under the dash and the connector at the driver side firewall bulkhead?

 

I am so glad you are her Trickster, no I did not replace the wiring harness under the dash, just from the ecm and connector out thru pass fenderwell, across back of engine, to the bulkhead on the d.side firewall. (complete engine, ecm harness underhood to p.side from 87 tpi) I hope that all makes sense.

 

Well, as I'm sure you're finding out the hard way, there is quite a bit of difference in the wiring between those two years as far as the under dash wiring goes. You will find that not all the pin connectors and wires are compatible with each other. give me a moment to scan the two firewall connectors in and you will see the difference. That other connector that you were asking about is connector C207 and I don't believe that it was in the 85 models by that name, will have to check the schematic.

 

Yeah, C207 is what its called,16 pin two rows, the 85 also has a 6 pin that the 87 harness doesn't have.

I sure wish mine could be as simple as Jim85IROC's swap was.

 

I'm not sure but I think that Jim did a complete wire swap out when he did his.

 

Hey John, before I can get the ECM wiring for you on the 85 I need to know what engine was in it originally.

 

This is the original engine in it, 1985 5.0 tpi, put in an 87 engine harness/ecm/prom.

There was an exhaust leak which ignited a sudden fuel leak and burnt the wiring harness. I was unable to find an 85 harness at the time and didn't want to have a bunch of repaired wiring. wondering if I should have just repaired instead:lala:

 

I replaced the engine harness only. Absolutely EVERYTHING else from my 85 plugged directly into the 165ECM and works 100%.

 

I have almost the same problem. I've got an 89 and I swapped the v6 to a 350. I got all the wire harnesses from an 86 firebird. The fuel pump doesn't do anything on mine either. I know the wire harnesses are different. I haven't even tried to spray starting fluid in it to see if it will start. I just put the motor together last week. I would appreciate it very much if you guys would let me know how this turns out.

 

johncoo5 can you please help me. I'm having the same problem you did with 85 to 87 harness conversion. Can you please tell me what you did and what you had to repin. I'm using a 87 engine harness,with the 85 c100 harness.Please help so I can get this car to run once again. Thanks.