My car eats computers!!??? (DMEs)

[echrisconnor]

Help. I've got this 87 924s that eats DMEs. Each year the computer craps out. Each year I buy another one from a junkyard, plug it in and it starts right up again. This is the 4th one in a row now over about the last 4 years.

I used to think the problem was moisture, since I had a battery compartment leak as well which commonly created moisture around the DME and a wet floor. That's been fixed and I still lose DMEs. I've checked the voltage, and I'm getting about 13.6V constantly. No peaks to note... Maybe that's a little low, but could that and the VR in the Alt. be the problem?

Any advice would be appreciated.

Chris

[AaronM]

The 942S DME is mounted under the steering column, not under the passenger floorboard... Did you mean 944S?

[Brando]

You've possibly got too much voltage going to the DME, or possibly a short in the harness going to the DME.

I'll check my PDFs when I get home, but you should bust out your multimeter and start checking leads...

[echrisconnor]

Thanks all,

To note: yes this is a 87 924s. The note of the water on the floor was to indicate that there had been water leaking in to the vehicle, and not to suggest that the DME was on the floor.

Regarding voltage, it would seem that somehow spikes are killing it, but given that it only happens once a year or so, they must be very intermittant. I'd like to explore along these lines though.

chris

[Icey1174]

What are they doing to the DME? Are you just getting bad DMEs with cold solder joints or is it a bigger problem than that? I would try resoldering one of the old ones if you still have one and see if that helps any.

[Eldorado]

i'd agree with John. Inspect all the solder joints.

[bazar01]

Before you buy the 5th DME, try opening the last one that failed and you may be able to see the failed component.
When my DME failed, I bought a used one, and they are not cheap. DME failed due to water leak in pass side.
I installed the spare used DME just to test it and the car fired up. I got spark.
Pulled it back out and tried to repair the broken one. Luckily, I found the component that got hot that broke the PCB copper trace.
Posted the burnt pcb on Clarks-garage and georgeb was kind enough to post the original pcb copper trace.
All I did was put a jumper wire to connect the copper trace and it worked.
Turned over the car to my son and still driving on the repaired one.

[Icey1174]

Is there anyway to seal your DME unit to make it water tight or reasonably water tight? The correct fix would be to fix the root cause, but this may save the some of life of the new DME.

[ae1969]

Check and clean all your grounds. If the grounds are not making a good connection then the DME becomes your ground.

Not good.