QuestionQUESTION: We just purchased a Town and Country AWD from a distance, when we got in to drive it the problem soon became apparent: when using either side turn signal some kind of "short" draws down the instrumental panel function (lighted panel dims and speedometer quits). Before fully comprehending, this afflicted the speedometer so as to not work at all. The problem is signal malfunction and somehow that connection to the instrument panel has caused the resulting problems. Thank you for any help.
ANSWER: Hi Mark,
There is one fuse that supplies power to operate the cluster, #24 (20 amp)in the box under the hood by the battery. It os located on the in-board edge of the box next to the 'accessory' relay.
Something is apparently drawing too much current from that fuse when you use the turn signal. But the only bulbs other than those in the instrument cluster that 'draw' on that fuse are what are called the 'repeater bulbs' that are only used on the export models, and both would have to be faulty because they are turned on independently of oneanother by the body computer. The only other draw on the fuse is the "message center", and it wouldn't have any relationship to the turn signal function as far as I can tell.
Similarly, the turn signal bulbs in the cluster are turned on independently for the left or the right turn indication. So I don't quite see what could cause the problem no matter whether the left or the right function is activated. Clearly, fuse 24 must be being overdrawn but I can't identify why, unless there were a short of some sort in the cluster printed circuit board.
I assume that the exterior turn signals bulbs all work properly, if not let me know. How about the brightness of the turn signal indicator bulbs in the cluster, are they normal?
Take a look at fuse 24 to see if it is blown. There is a diode associated with that fuse socket which may be shorting to ground but I am not sure why the turn signals would exacerbate that possible mal-function. You could read the resistance to ground that the fuse "looks" at by putting an ohmmeter on the 'cold' side of the fuse socket (not the hot side which will show 12v at all times). Let me know what that looks like with and without the turn signals activated.
There is a self-diagnostic test for the cluster: with the ignition off, press and hold the trip odometer reset button until the word 'sof' and a number appear in the odometer window. Then release the button and watch for either a four-digit number (which would be a fualt code) or the work 'end' appears. Let me know if you get such a number, otherwise no faults are recognized by the cluster itself.
It is an interesting problem, so let us see what you learn.
Roland
---------- FOLLOW-UP ----------
QUESTION: Roland, Following up: Pardon for the slowness, amongst all of normal daily routine, we try to figure out this auto electrical problem. The 4 signal bulbs did light until now; none light presently so not sure what we did. Tried a new signal switch lever...nothing. Have waded through a service manual reading about Front Control Module and Body Control Module. Haven't heard back yet from dealer if any service was performed recently that could be related somehow. Mechanic friend is suggesting a side by side cross check with a comparable model van. So those are some of the things we have tried and are hoping to try. Still no fix! Any suggestions?? P.S. Self diagnostic check came back with No Fault code.??
AnswerHi Mark,
The turn signals circuits and power therefor all come out of the body control module so now that you have lost the turn signals I would wonder if any of its power supply fuses have blown: 14,19,20, and 24 are the ones to verify. So check those out and let me know if you find one that is blown.
Roland
