1990 4.2 the temp gauge wasn't working when I purchased it so I checked the sending unit to see it it was plugged in. Nope. So I plugged it in and it worked for a day. I replaced thermostat thermo housing and coolant sending unit. It still doesn't work. I pulled the dash apart tonight and couldn't see anything that looked messes up. Am I forgetting something? What else can I do? The gauge flickers just a tad when I turn the key onto the "on" position.