My 1999 Dodge Caravan Has Bad BCM
How to Repair a Minivan with Speedometer, Fuel and Temp Malfunctions
Repair advice for a 1999 Dodge Caravan with malfunctioning speedometer, fuel and temperature gauges.
This weekly Q&A session answers your questions about cars and trucks. This week explores a 1999 Dodge Caravan that has multiple malfunctions.
Question
My 1999 Dodge Caravan speedometer, fuel and temperature gauges are not functioning. Following your advice, I tried pressing the trip/reset buttons to get a code knowing beforehand it wasn't going to work. Neither odometer or trip meter is functioning, and the front windshield wipers won't park and the rear one does nothing.
All the upper lights, turn signal, high beam and check engine light are functioning but the lower ones; door ajar, seat belt, fuel warning, cruise, low fuel and low windshield washer, etc… aren't. I removed the cluster today and the Haynes motor manual shows 5 wires at the connection and mine has 6 (?) I was going to test the circuits but am at a loss on printed circuits wiring.
First question: can this be done by a layman and/or by a shop? I am going to remove the BCM hopefully to test it if not replace, not knowing cost of said items.
Second question: would you recommend used parts from a reliable junkyard? The only maintenance done on this vehicle electrical was a used starter.
Third question: what about the alternator, could that possible cause these problems? Oh yes, and when the parking or headlights are on, the instrument lights flicker. I need help, don't want my wife to run out of gas. If either the fuel gauge or odometer worked, we would have it whipped.
Thanks ahead of time,
Mike
Answer
The Body Control Module (BCM) controls all the systems that are not functioning, or functioning improperly. Since the chances of all these systems having a malfunction at the same time are miniscule, the BCM is most likely brain dead. If the problem is in the Instrument Cluster itself, the Instrument Cluster can be reprogrammed before any other diagnostics are performed.
The answer for your first question is: Your Dodge Dealer can best confirm the bad BCM. His scan tool can interface with the BCM and all its functions can be checked independently.
There is nothing wrong with used parts from a junkyard. Just make sure the BCM you buy is exactly the same part number as the one you have in your vehicle. You probably won't get any kind of warranty with it since electronics are not generally warranted.
The alternator could possibly cause these problems, but not very likely.
My wiring diagram shows a 13-pin connector going to the Instrument Cluster circuit board. It makes little difference however since there are no specifications on the circuits and test points. Also the chances of damaging the electronic components in the Instrument Cluster are very good if not tested properly.
That's all for this week. Feel free to browse the archives for past topics and other resources. And, as always, if you are stuck and need an immediate answer you can always call Vince on the phone.
