How hard would it be to convert from pre89 to 89+ ecu/harness?

[empera]

so i've been seeing more things compatible with the 89+ than the pre89 ecu's and stuff, so i was wondering if i can switch over from the pre89 ecu and wiring harness to a 89+ wiring harness and ecu? would i need to change anything else?

thanks.
-emp.

 

[Poodles]

pretty easy, but the plugs for the body harness aren't the same, and need to be repinned...

engine wise, it's pretty much the the ECU temp sensor is different along with being more sensors on the t-stat housing IIRC...

 

[kyle1jzsupra]

tht pretty much summed it all up right there lol^^^

 

[thevork]

If you take a 91+ (which is also 89+ ) be prepared for even more connector rewiring/replacing. the 89 and 91+ also have differences. Like the plugs near the ignitor

Better take a 89 or 90 loom.

 

[empera]

What exactly needs to be rewiring and/or replacing?

 

[thevork]

See pooldles reply.

 

[empera]

im sure theres more to that...than wat poodles posted.

 

[Poodles]

never done it myself, but it's going to be one of those things where you have to have both harnesses in hand to see the differences...

 

[empera]

well i have my buddy's 89 to look at and compare...has anyone actually done this?

 

[Poodles]

Yes, dunno why nobody is commenting on it...

 

[super.secret.supra.club]

I'm doing it. I'd have to say it's more of a hassle since I didn't do my homework until I was staring at 2 different engines: 1 of them an 88, and the other a 90. Just think of an 88 being fully transplanted into a 90.

If I could go back and change paths, I would've picked up a 89+ car for the full swap. Or maybe kept both my cars the way they were and gone with a 1J.

 

[Jaguar_5]

I can tell you one of the plugs on the ABS motor definitely won't match up

87 has a 6 wire plug, 89+ has 5 wires...

That's all I know on the subject

 

[super.secret.supra.club]

Ahh geez. There was actually a thread a while back that touched up on this topic of the pre-89 and post-89 differences in the mk3. I could've sworn I bookmarked it for reference later when I was working with my mk3s.

Off the top of my head I've got:
1) The ecu/harnesses.
2) The a/c system-climate control has a different plug(3 vs 4 connectors).
3) Driver & passenger side door wiring.
4) There's a harness on the belly of the steering wheel that turned out to be different on my swap(plug & part # difference).

Correct me if I'm wrong and most likely missed even more. It's late and I'm staring at jugs in the VIP section. :boobies: