03 ranger temp control knob-causes temp gauge to spike
 

Happy Holidays 2 all. A friends son purchased a used 03 ranger. Base model, 4 cyl., 5 spd. manual, 2x4. The problem: When the temperature control knob is turned from cold to hot, the temp GAUGE spikes, like it's being grounded out. When temp knob is turned back to cold, the temp gauge returns to normal. I haven't seen the truck, yet, to do any testing.

Has anyone else had this problem?? Does anyone know/have the wiring diagrams for the temp control and temp gauge?? They must be wired together. What else is wired with them?? Many Thanks to any that can answer!!!

RE: 03 ranger temp control knob-causes temp gauge to spike
 

Check the coolant level. I am not positive but if you look at the hearter hose you will notice there is a control valve just before the fire wall. When the temp is changed the valvu opens allowing flow. If the system is not right full, IE air pocket, do to in proper coolant flush and fill or the like you will get an air pocket. I do not know the 4 cyl, but on the 3.0 the middle of the returnradiator hose is the highest point in the coolant system. You have to heat theengine and top it off after the thermostat opens or risk air pockets. Thetemp sensor isnot in afluid path it is actual in a hosing just forward ofthe thermostat hosing. Great place for air to settle. So when you release system pressure by opening heatercore valve you geta hot spot in this area.

RE: 03 ranger temp control knob-causes temp gauge to spike
 

Thanks Tom. Makes sense to me. I've forwarded your advise and should hear back in a day or 2 if it has solved the problem. I'll let you know. Thanks again!!

RE: 03 ranger temp control knob-causes temp gauge to spike
 

Hey Tom. Sorry for the long delay. It was fixed yesterday and you feel free to pat yourself on the back !!!!! Air pocket in the coolant system. That was the FIRST thing they wanted to try, and YOU ROCK ! ! ! ! ! Thanks a bunch 4 sharing your wisdom!!