Hi, I'm new to this forum. I have a 1989 ford e350 Super Wagon with a 7.5L and C6 transmission that I use to travel with my band in. Were leaving for Florida Thursday morning and are having some trouble. After thinking my van was overheating and changing most coolant components I found that my dash was malfunctioning. The temp gauge and oil pressure gauge are showing much higher than they actually are. I've tested this a few different ways and know for sure. I'm sure it's a bad ground in the mess of wires behind my dash. If I turn on my heater full blast and start the truck the blower doesn't work unless I put it in gear or hit the steering wheel with my palm. I took the dash out today and wiggled a bunch of wires and it temporarily read correctly. But when I re installed the dash cluster it read high again. Can anyone help? Would someone know what ground controlles those gauges? Thanks!

 

The IP ground should be located on your Brake pedal support.
You might also check to make sure you have a good body ground from the NEG battery post to the body and not the frame.