Does your vehicle have ABS? If so, when the panel is not working, does the ABS warning light come on and stay on full-time?
If so, I just recently solved the same problem on my 1998 Grand Caravan Sport. For about a year or so, the instrument panel would occasionally go dead (just the odometer and gauges panel illumination worked, as did the various warning and indicator lights in the strip above the panel except as noted below), but could be brought back to life with a well-placed thump on the dash with a rubber mallet.
Eventually, it quit working completely. Any time the panel was dead, the ((ABS)) warning light was on full-time while the engine was running. Sometimes the check engine light would come on, but would eventually go out on its own. I had the codes checked once at AutoZone. They said it was complaining about the EGR system, but the engine runs just fine. I am not positive, but I suspect that the error codes were a just side-effect of the malfunctioning panel.
As it turned out, the problem was caused by a poor solder joint on the instrument cluster circuit board, where the socket for the chassis wiring connector is attached to the board.
If you have already had the thing apart far enough to get the panel out. Try just wiggling the connector around with the ignition switch in the "run" position (second detent) and see if you can get the panel to light up. I got mine to the point where merely tapping the side of the connector with my fingertip would make the panel kick in and out.
Note: With the panel disconnected, you should read twelve volts on the pink lead in the chassis wiring connector with the ignition key in the "on" position. If not, the problem lies elsewhere.
If so, and you know how to use a soldering iron, you should be able to fix it yourself.
1. Remove the Phillips-head screws that hold the protective cardboard panel on the back of the module and remove the panel.
2. Remove the Phillips-head screws that hold the board in place.
(Note: All of these screws are the same size, so no worrying about which one goes where. It's been a while since I had it apart, but I believe there are a total of twelve screws, six for the protective panel, six for the board itself)
3. "Carefully" remove the ribbon cable from the connector at the bottom center of the circuit board. It should just pull straight out of the socket, but be careful not to bend the thing around too much once you get it loose.
4. Snap the board out of the module so you can get at the back side of it. (There are spring-loaded connectors on board that snap over the pins on the backs of the gauges just pull the board straight out the back of the module).
5. On the back side of the circuit board, touch up all of the solder joints that connect the chassis connector pins to the board. Reheat them just enough to get the existing solder to flow and apply a "very small" amount of fresh rosin-core solder.
(I am assuming that you know what a proper solder joint looks like no "blobs" or "whiskers").
Caution is the word here, do not apply too much heat or the circuit traces will peel away from the board. Allow each pin to cool before touching up the next.
6. Snap the board back into place over the pins on the gauges.
7. Reconnect the ribbon cable at the bottom.
8. Replace the screws that hold the board in the module. Finger-tight is plenty, you are putting metal screws into plastic holes. You do not want to either strip the holes or crack the board.
9. Reattach the protective cardboard panel.
10. Connect the module to the chassis wiring harness and test it before you screw it back into place in the vehicle (i.E, save yourself the hassle of wrestling it in and back out again if it does not work!). The odometer should turn on at the first detent of the ignition switch, and the gauges should come to life at the second detent.
10. If the panel works, the ABS warning light should go out, and the check engine light may go out after you've started the engine a couple of times. Mine did, and has not come back on since. If you want, read the codes and reset the light, then wait and see if it comes on again.
Monday, March 1st, 2010 AT 3:50 AM