was driving my 89 full size bronco the other day and noticed that my temp gauge was pegging cold all the way to the left, even after the egine had warmed and even with the aircon on, now when i return the ignition switch to the off position the needle on the temp gauge then moves off cold towards warm, what would cause my temp gauge to peg the c all of the time, hope its not electrical, could it be temp sending unit to the gauge, any ideas, i bought this truck brand new and have had no major problems with it at all, it has 59,000 original miles and has been well taken care of, any ideas or help you could provide would be greatly appreciated, thank you, don

 

An easy way to check the wiring/gauge itself is to remove the wire from the sending unit, and short it out to a GOOD ground. If the temp needle pegs all the way to HOT then the wires and gauge are fine. If not, check the wire to the gauge. If all this is fine, it should be safe to assume the sending unit.