QuestionI have an intermittent electrical problem with a '97 Dodge Grand Caravan. It has 162500 miles but works fine for the most part. For about a year, the gauges in the dash would occasionally stop working, fall down to zero, and the ABS and Service Engine lights would come on. The computerized mileage display would also stop working under the gauges. The van continued to run fine and the gauges would always start working again within 20-30 minutes or after we restarted the van.
In the last two days, the gauges and electronic display have been flickering and then stopping. The ABS and service engine lights come on, but the battery indicator light has also started to come on when this happens. It still runs fine, so I have stopped when I get to where I'm going. Then there is a click-click-click noise inside the dash that can only be stopped if I turn the key to an on position. It clicked in the off and auxiliary power positions. The van won't start immediately and the drive shifter locks up for a few minutes. Then everything loosens up, I can start the van, and everything is back to normal. No indicator lights, no clicking, no visible problems of any sort.
We don't know if this is related, but we've also noticed that occasionally (3 different times over the past year) the transmission seems to stick at a higher than normal RPM. If we turn the van off and wait a few minutes, it always starts back up normally as though there's no problem at all. This high RPM thing doesn't happen at the same time as the gauge issue though.
We are reluctant to take it in right now, because there are no lights on at the moment (even the service engine light goes back off) and we don't know if they'd be able to figure anything out from my description. Can you help us diagnose this? Thanks so much!
AnswerHi Shawn,
There is a digital communication system in the van that ties together the instrument cluster, transmission controller, engine controller, body computer, message center, etc., and that sounds like it is the basic source of the problem. It has a tree of twisted pair wires that connect all these parts, and the wires are polarized at +2.5 and - 2.5V to carry the bits of data. The data to run the gauges, to shift the transmission (the higher RPM was probably due to the trans being put into 2nd gear in what is described as limp-in mode). The only thing that I can't identify is the clicking sound but that must be a relay that is perhaps not being given sufficient power to remain closed. If you can locate it specifically that would be helpful. Look under the dash for the junction (fuse) box which has several relays.
The most direct approach would be to plug a Diagnostic Readout Box III ( a Chrysler test tool) into a socket under the dash next to the steering column and attempt to readout fault codes store in the controller memories as well as to trouble shoot this communication system. That can be done at a dealer who has the tool and ideally a knowledgeable technician to try and locate the source of the problem. You might nonetheless want to check the battery cable clamps and on the -post wire to follow its several branches to the points on the body, transmission and engine to make sure that the ground attachments are shiny and tight. If the battery is nearing the end of its life there is an outside chance that it has a loose plate internally that is causing a noisy power supply which can through spurious signals into the communication system. From there though it probably would be most rapidly resolved with the readout box in the hand of a competent tech.
Roland
