I have an intermittent 'Service Engine/Service Vehicle' light problem with my 1992 DeVille 4.9. About every 100 miles, the 'Service Engine Soon' light comes on, and then the 'Service Vehicle Soon' light also comes on. These lights will stay on for a few moments, then one or the other will go off, and they take turns coming on and off - sometimes both are on and sometimes only one is on. After a few miles, they both go out and everything is fine for another 100 miles or so and the phenomena repeats itself. The vehicle has no obvious performance issues when the lights do this -- everything seems to be running just fine. The only other clue I have is that when this occurs, the 'Fuel Data Center' goes to 'zero' - i.e, the instant fuel economy reading reads zero, the gallons used works but doesn't ac***ulate more fuel used, etc. The fuel in tank seems to keep working fine.

I ran the OBD by pushing the Climate Control 'OFF' and 'WARMER' buttons with the key on and the codes displayed were 'E47' and 'F32'.

Anyone have and ideas as to what this might be?

 

E47= BCM to PCM data fault. This could be set by a bad ignition switch, but more info/diagnostics is needed.

F32 is the same code, just set in the BCM instead of the PCM.
What these codes mean is that the BCM and PCM are not communicating at some time or another.

BCM= Body Control Module
PCM= Powertrain Control Module

The erratic nature of the lights/codes seems to point to a loose wire/connector, possibly at either the PCM, or the BCM. I was looking at the diagnostics for these codes, and it gets fairly involved. I could probably post the procedure here, but typing it out would be a pain with one finger! I'll see what I can do to post/e-mail a little more info on how to determine the source of the problem, unless someone else can sooner.

 

Thanks - I appreciate the help on this.

 

Here is some info on these two codes. Looks like a connector, or wiring issue that is causing both codes to set together.

 

Update 19 April 2010 - checked all of the connections between BCM and ECM and found no problems; eventually resolved the issue by replacing both the BCM and the ECM - Auto Zone had the parts for about $100 each; replaced the BCM first and that resolved one of the codes but not the other, so replaced the ECM as well and that resolved both codes. Car is running fine now with no service engine or service vehicle lights or recording any codes.

Thanks for everyone's help on this.