JonnyO78

Well how do I test the ECU for that? Should I source a salvaged one? Buy a rebuilt tested unit? I'm not so sure about spending that kinda $ unless I can return it if that's not the problem.

I got it cranked up again and it ran for ~30". Took it out on the road and drove it hard to put it to test. Was kinda stuttering and it got progressively worse with time, especially at higher speeds and RPM. Got it back to the shop and turned it off. And then it refused to start and is giving the code 12 again.

in other news, I ran the block test and it came back clear. Maybe I should run it again after it's been running longer, but I don't think that's the problem with my heat. But I do still have kinda white exhaust and my heat still doesn't work right.

AlaskanLS

What's the ECU number of your car, I may have spare one that can send you just for the price of shipping.

JonnyO78

Here's a pic! Another thing is this is obviously a salvaged ECU. Can I call Lexus and verify it is the correct ECU by VIN? Is there a block plate I can also verify?

AlaskanLS

I
I got this one, it is non traction control UCF10 . Check the ECU list on this website to make if this one will work for u.

AlaskanLS

I guess the one I got will work for you.
Here is the list:
90-93 model
Part Number, Production Date, Model(Description)
89661-50010, 05/1989-08/1990
89661-50020, 05/1989-08/1990 W(TRACTION CONTROL)
89661-50030, 05/1989-08/1990 CALIFORNIA SPEC
89661-50031, 08/1990-09/1990
89661-50032, 09/1990-08/1992
89661-50040, 05/1989-08/1990 CALIFORNIA SPEC & W(TRACTION CONTROL)
89661-50041, 08/1990-09/1990 W(TRACTION CONTROL)
89661-50042, 09/1990-08/1992 W(TRACTION CONTROL)
89661-50140, 08/1992-01/1993
89661-50141, 01/1993-08/1993
89661-50142, 08/1993-10/1994
89661-50150, 08/1992-01/1993 CALIFORNIA SPEC
89661-50151, 01/1993-01/1994 CALIFORNIA SPEC

JonnyO78

I'm pretty sure it wouldn't because it's a 90-92. I can tell by the plug map. Mine's a 94.

AlaskanLS

Well get one from eBay from seller that accepts returns. It's worth a try.

JonnyO78

Well, after a thorough inspection of my harness, I found that the clip on one of the coils was broken, so I have it held down with a zip tie until I can replace the clip.

But in other news it seems that my fuel pump ECM is going out. I have it jumpered at the diagnostic port for now, but I'd rather not reduce my MPG. I'm trying to find the ECM work around on here. Something about a relay?

JonnyO78

Ok! I'm not 100% sure about the fuel pump ECM, but I finally changed the plugs and wires and now it's running smooth!

tl;dr: Code 12 means check all your timing sensors, ignition wires, and probably perform a tune-up.

JonnyO78

Oh my damn it came back!!!

JonnyO78

Ok. So it's been running a bit, but I haven't been pushing it too hard; it's currently up on jacks while I work out some cosmetic BS. Swapping around wheels and inspecting the suspension; I found the RH front shock support is cracked.

I've noticed a minor coolant leak towards the back. I'm wondering if I don't have an issue with a leak in the coolant system soaking my harness and causing a short at some point of wear back there. I'm going to go ahead and focus on my 91 for a bit so I can get it sold. It's looking like I'm gonna be pulling the top end off this one to locate the problem.

Also, I got a ToyOBD1 and the most noticeable thing is both banks keep flipping between rich and lean. What can be doing that? Should I check my O2 sensors? Could that have anything to do with the cutting out and the subsequent code 12?