Wipers and lights with gremlins in them.

What is your question?

1997 dodge grand caravan LE 3.8. Front & rear wipers not working. Checked motor, multifunction switch, fuses & relays, all are good. Front washer works, rear washer doesn't. When hit with the power probe at the BCM wire harness back wiper & washer work. Need all the layman's help I can get. If u could go over in great detail how to check wire harness with a multimeter would be great help. What wire/color to check what reading should or shouldn't they have for voltage and resistance in high/low/intermittent. It's a 4 wire harness red/yellow, brown/white, green /white, black. Go over the relay posts in the PCM and what readings should I get with a power probe and multimeter(ohms & volts). Some people say it could be the BCM but the vast majority believe it's a bad wire or ground. Hope I covered it. TIA

What makes this problem better or worse?

Nothing changes it

How long has your 1997 Dodge Grand Caravan had this problem?

Couple of weeks