I've read about loose connector pins on the back of instrument clusters in newer Caravans. Soldering them to the copper circuits solves many intermittent problems.
Older Caravans, like mine, have a circuit board plugged into the right side of the instrument cluster, in the back, but they give very little trouble. Unplugging these kinds of modules and plugging them back in will often solve intermittent problems by scratching through a film of corrosion. The permanent fix is to clean the slide-in contacts.
Some older front-wheel-drive cars from the late 1980s to mid '90s could develop sticking and jumping tachometers from the plastic laminate shifting position after the glue softens on hot days. The pointer base rubs on the laminate making the pointer stick. Careful trimming with a hobby knife is easier than trying to shift the laminate back to its proper position.
Don't know if any of those ideas pertain to your car. Also, due to its age, you should have an easy time finding an instrument cluster in the junkyards. The odometer would be wrong, but it would be an easy test to see if the problem is in the cluster or somewhere else. On newer cars, there are not separate wires going to the cluster for speedometer, fuel gauge, tach, signal lights, etc. All information is sent on a pair of "data buss" wires and interpreted in the cluster to be displayed on the gauges and lights. That means that just one item can't be dead due to a wiring problem. It must be on the cluster. Older cars use individual wires for every function. They are much more reliable due to the lack of all the delicate computer circuitry, but it is possible for just one thing to have a connection or wiring problem. I'm not sure which system is used in your car, so swapping the cluster as a test is a fast way to narrow down the problem.
Holler back if you would like to try a different cluster but can't find one. I'm heading to a huge salvage yard within the next month or two.
Sunday, March 22nd, 2009 AT 2:33 AM