My caravan had all the lights on the dash lit up... transmission was slipping....no speedo....throwing code P0500-speed sensor system...from advice on here I changed input and output sensors....now things are worse still no speedo...a/c-heater fan starting in power off position...all lights on the dash remaining on even with key removed from ignition...tailgate open light on when tailgate is closed...where do I go from here I had such hopes that the sensors were my problem but with 4-5 days of rain coming i need to fix this...biking to work sucks in the rain...thanks in advance for the help...

 

Good place to start is the IPM (fuse box). They are a known issue on early 4th generation vans. They are regularly plagued with corrosion problems. Disconnect the negative battery cable then disconnect the connections and inspect for corrosion and any contact damage. Clean with electrical contact cleaner. If that doesn't help you'll have to remove the IPM and access the internal circuit board. If it's corroded replace the IPM.

Another conmmon fail point are the wire harnesses around the engine and transmission, especially those near the exhaust. Insulation melts, wires short to ground. A harness running under the battery tray is another. Acid drips on the harness melting insulation and corroding/breaking wires. Wire harnesses running under powered sliding doors is another.

If all that looks good you may have a data bus problem. Common fail points are the instrument cluster connection or the cluster itself, the BCM, TCM, PCM, or HVAC control panel connections.