I did a search but it didn't address the question I have. The extent of the wiring harness to change. Below are my guesses. Heres the parts list... Outside: 1) ECM harness from the firewall to the engine. (Yes) 2) "Body" harness from driver side firewall to frontend. (No) Inside: 3) ECM to the firewall (other part of #1 above) (?) 4) ECM to the rest of the under dash stuff (?) 5) The rest of the under dash stuff and along with it the rest of the body. Plugs in about a foot from the ECM. (hope not) Here might be the catch. 1990 Iroc 350 TPI Auto into a 1991 Firebird 305 TBI T5 and am keeping the T5. I have the complete donor including auto, wiring, rearend, and suspension. Thanks, next weekend I hope to start. The engine is running perfect now.

1) & 2) correct.

3) Change.

4) No change needed.

5) No change needed.

You'll have an unused portion of the tranny harness, the 4-prong square.

Thanks! I guess I'm in business. Man, I feel too old for this.

I started mine when I was 44 years and 5 months old. Stop your whinin' . . .

Well, I guess I can't complain. I just turned 44 today. I unhooked the battery and went inside. That's a good start.

Not really the age, just burnt out right now. Working two jobs, 6 yr old and 5 mth old kids, oh, don't forget the wife.

I hear ya. I remember the first time I saw a 3rd gen for less than $8000 - that was about $7950 more than I could afford at the time. . .

Oh, and Happy Birthday!

I've been searching to figure out if I can use my 87 305 TPI wiring harness for my 89 350 TPI engine swap without posting my own question. I guess I'm asking about the #1 question asked by FNFAL308.

Thanks

'89 didn't have the cold start injector. I'm not sure if that drove pin-out changes, or you'll just have a connector that doesn't go anywhere.

Better to ask on the TPI forum.

I know we're talking about swapping a 305tbi to a 350tpi here...but does the same hold true for swaping a v6 to v8 as far as the wiring harness swaps go??...are the interior(fuse pannel)wiring the same for all 3rd gens..am I thinking corectly that only the engine wiring harness changed??

No, and No.

Things like digital vs. analog dash, VATS or no VATS, carb'd vs. EFI, etc., changed from year to year, and from 'Bird to Camaro of the same year.

Came back around to this post again. Started pulling the wiring this morning for the swap. Again, Donor = 1989 IROC 350 TPI, going into 1991 Firebird 305 TBI.

Man it's a lot of wires. It would be easier if I could just undo the connection at the firewall and the ecm connector and swap all the under hood stuff over. But I don't think that will happen.

What was everyone's good way of separating the ECM wiring from the body/basic engine stuff? Strip all the wire covers?

About (not looking for exact numbers) how many wires will I have to splice back into the 91 basic engine/body stuff? Meaning how many are shared?

Will there be a noticeable separation between the majority of the wires?

There are two conectors on the back of the ecm and one white one that connects to something under the dash. Is the white one part of the ecm loom or can I separate it out too.

That's EXACTLY what you should be doing. Disconnet the harness at C100 ( drivers side firewall ), then remove the headlight harness from the engine harness. Then unplug the ECM and feed the harness through the fender well and into the engine bay. from there just remove the entire harness from the engine.

The 89 and 91 harnesses are pretty similar. The one pair of wires I know you will not have and will need on the 89 harness is the electric speedo sending unit for the tranny. ( 89 Camaro was cable and 91 Firebird was electric ) Your BEST BET is to get the wiring schematic for the 89 IROC and the 91 Bird that your harness came from and match the wiring up. Since the Firebird headlight harness is different than the camaro style - you will want to keep that in place and intact.

Trying to rip open the harness to pick and choose what wires to keep is a fools errand. Get the C100 diagrams and make comparisons - that way you can simply add any additional wiring you might need.

Just got thru pulling all the wiring. I see what you are saying now - athough I didn't think about the speedo even though I was looking at the mechanical one when undoing the 700r4 wires. Crap. Had a short in the speedo anyway.

The A/C wiring is separate. The body wiring is separate.

The only other issue is the windshield wipers and starting circuits still in the motor loom which I'm betting/hoping is the same at the firewall connector.

On the speedo I'll have to find where the wires are supposed to come out of the connector and hope they are not in the donor wires coming out for something else. If they are empty, I'll transfer the prongs (or whatever) from the 91 to the 89 plug and plug it in to the 91 firewall. So, I may have to move/run some wires but most likely not many.

Now I just need to get a wiring diagram of an 89 and 91 and a bottle of good scotch. I'll be all set to pull all of my gray hair out.

anyone on here got a real picture of a 89 camaro wiring harness? I removed the a/c kept the heat....it is a L98 engine from a 89 formula put into a 87 camaro. I got ALOT
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anyone on here got a real picture of a 89 camaro wiring harness?

I removed the a/c kept the heat....it is a L98 engine from a 89 formula put into a 87 camaro.

I got ALOT of spare connections, can anyone help me out?

Save yourself a lot of grief and buy this guys harness:

http://www.thirdgen.org/techboard/en...tml?highlight=

thats a speed density harness, and im using the maf version. im pretty sure they are not interchangeable...

That was for the other guy.
He is putting a '89 MAF into a speed density car. Not a good idea.

oops, sorry

I'm putting a MAF in mine also. From the 89 IROC.

That's my point, just buy the guys Firebird harness because it's a plug and play. I know you will regret having done the other way when you are done.

As near as I can tell, that is for a MAP - 1989 was the last year for MAF - I think. He said he took it out of a 1990 and rewired it for a 1991. I am taking a MAF out of a 1989 IROC and putting the MAF in a 1991 Firebird. I am not changing to MAP.

But, I may be wrong about his being MAP, so I posted there.

His is for a MAP.

Why would putting a MAF in my car not be a good idea? It has 305 TBI now, and I have a 350 MAF. So in goes the MAF. Sounds like a no brainer to me. If I had a MAP then in it would go.