Intermittent diagnostics

[Guest jcc3inc]

Hello All,

On my '91 I have inability to enter diagnostics after the system has warmed up. When cold or before starting all the info is available. However after it has run a while (and I presume warmed up), the inst panel will only briefly "flash" as I hold the buttons to start the analysis. This also results if the car has been run, and has just been shut off. The manual says all info comes thru the BCM even though it originates elsewhere. Therefore I wonder if the warming-up of the BCM might result in being unable to read the codes. Possibly getting the unit into the open (to cool???) might help? Has anyone encountered this problem, or are there other suggestions?

Thanks,

Jack C.

[Don B.]

I don't know about '90 or '91.

However, the alternator could be over charging the battery.

This may result in the BCM rebooting.

With a volt meter check voltage at the battery with the engine

running it should not be over 14.8 vdc.

[2seater]

Do you ever have a problem changing the desired climate control temperatures or function? It is possible the contacts inside the climate control module need to be cleaned. I had a similar instance several years ago where the temperature would only adjust lower and refuse to raise the temperature. Occassionaly it would be fine. Cleaning the internal contacts cured both problems.

[Guest wally888]

Had same problem for several years (a 91) and sometimes trip odometer fails to start after clearing (returning to Zero). Usually starts after <20 miles driven.When not working then car is shut off, when restarted it shows the distance before clearing (returning to zero!).

Think is an IPC intermittant problem.