I just purchased a 2005 Dodge Grand Caravan and for the past two months the needles on all my guages on the instrument panel go crazy; my ABS brake light, my regular brake light, my radio and my air conditioner go crazy right along with it. At night if it starts doing it my tail lights and my head lights go on and off with my gauges. I have replaced the battery, new battery terminals, the dealership where I purchased the van claims they have taken it to the Dodge dealership to run diagnostic tests on it only to show nothing is wrong. Any ideas as to what the culprit could be?
My old Cavalier had strange symptoms several years ago including dash gauges going wild as I recall. The fix was easy, clean two ground wire connections on the bell housing. The connections were corroded due to winter road salt. Possibly yours might be similar. If this works for you too, you might want to coat the cleaned connections with silicone grease to waterproof them.
The problem you are having doesn’t require any specialized test equipment to locate the trouble except possibly a common voltmeter. I suspect the trouble is due to a bad power connection in the main power distribution panel under the hood or possibly after it. If the areas you mention having trouble are tied to a common power point then that is where I would look for the trouble. By using a screwdriver hande to tap on suspected trouble spots you may be able to pin down the fault. The trouble could also be with a ground connection. You could tie in a temporary ground jumper between a know good ground point and a suspected bad ground point area to see if that changes things. If the jumper corrects the trouble then you know you have a bad ground connection.