1991 Reatta--electrical advice please

[Eclectic]

Thanks in advance to any kind souls who may answer my questions.  I am having intermittent electrical problems with my new car, and I need some help.  On most trips over ten miles, I experience an engine control failure as well as dash flashing, electrical problem lights, shut down of the IPC.  First the tach dies and the motor starts to cough and sputter, and will die if at low speeds.  Restarting the car usually stops this misbehavior, but not always. Diagnostics report 021 code or no code at all after one of these attacks.

I have a purchased a remanufactured ECM 77-1470, wondering if that is the most likely  part to change and where it is located on the car.  Thanks again for any advice you can give me.  Michael

[Ronnie]

I would like to help but to be honest I know very little about the 1991 model. You have 1990 listed as the Reatta you own in your profile. Which model is the one giving problems? Is it actually a 1991 as the title of your post suggests?

[DAVES89]

You might want to start with cleaning all the grounds and checking the battery connections. I think there is a tutorial listing all the ground points.

[Aztec62]

Eclectic,

sounds like a intermittend power supply/ground failure.

The first thing I would do is to get a factory service manual including wiring diagrams.

I have a 91 manual as pdf, but it is 328MB in size.

Then go look for all the ground wire terminals of the car and make sure you have perfect contact there and no corrosion.

Next are all plugs, fuse terminals and relays.

 

To put it short, check the whole electrical system for corrosion and bad contact.

 

The differences between the 1990 and 91 electrical power and ground distribution are not that big.

 

Dave, looks like you were faster than me this time  :)

 

Hope this helps,

Henning

[Eclectic]

Thanks guys, FYI this is the blue 1991, I also have a red 1990.  I just took the car for a spin and the problem has gotten worse,  I couldn't make it but a couple of blocks before the auto a-fib started again, poor running, no tach, this time no flashing dash or electrical problem lights, but it threw three codes,  E021, E042, E047.  We have had two days of rain, and the carpets are wet, windows must leak, perhaps junctions under the seats are giving trouble?  Do I remove the seats to check that out?  This car has 47000 miles and looks to have been garaged the whole time. 

Does this not sound like a computer problem? I can return the computer to Advance Auto.  What are the characteristics of a failing computer?  Thanks again.  Michael

[DAVES89]

Why are you looking for something bigger? Start with what was suggested by two people. If that doesn't do it report back and maybe we can try something else.

BTW we didn't know you had replaced a computer [which one ECM or BCM?]. But if you had put it in sometime ago and everything was fine that should be okay.

[Eclectic]

I haven't installed the new ECM computer, I looked at the two ground lug posts near the radiator, they look new and are tight. Battery connections are good, I am now worried about the wet connections under the seats, trying to avoid replacing the computer until I rule out simpler fixes. I also have the repair manual on a CD for the 1991, but couldn't get it to run on my laptop. Thanks for all of the responses. Michael

[Ronnie]

If you think the problem is the computer it would be easier to replace the ECM than it would be to remove the seats and carpet to get at the wire splices.

[Ronnie]

I don't think any of the wire splices under the seats would effect the tach. Check the ground connections on the intake manifold (if it is the same as a 1990).