I recently got a truck thats a 94 Chevy 1500. When it drives the speedometer is in the 70’s when im doing maybe 30 99% of the time and the needle is bouncing all over the place, the fuel gauge needle goes way over the full line when its full and the AC/Heating LED acts like someone is pushing all the buttons when I turn the external lights on. The oil pressure shows 20-60 and randomly went to 0 and when I checked the oil it was very low.
Any help with this? I only had the truck a week and im not sure wheres a good starting place.
This is more than a gauge problem. How many quarts did you have to add to bring it back to full? Are you checking it frequently?
Electrical grounds. Start there. A 24 year old truck has rusty grounds. This sounds like an electrical problem. Look for the ground strap to the engine from the frame, look for groups of black wires to a screw on the frame, and under dash. unscrew them, clean them and replace the screw with new.
That is where I’d start.
It was the thermostat ground. Previous owner changed the thermostat and hose but didnt pay attention to the wire being smashed in the metal.
I’d be looking a replacing stepper motors, a couple or 3 hour job for $25 or 3 to 500$ cluster replacement.
What is a “thermostat ground” anyway? I don’t think I’ve heard that term before regarding auto repair. Is this place where a ground wire is bolted to the engine, and they happen to use the bolts that hold the thermostat housing on as double duty? And this truck doesn’t use the early 90’s typical mechanical cable driven speedometer?
On this particular engine, there is literally a ground wire that attaches to one of the nuts/bolts which secures the thermostat housing to the intake manifold . . . as you surmised
This truck is almost certainly equipped with a 4L60E automatic transmission. If so, there is no speedometer cable for this particular application. The speed sensor responsible for the speedometer is located on the transmission, left side, I believe