Help temp gauge is stuck

Hulce211

New Member
Nov 1, 2019
4
0
1
36
Ventura, ca
So i have a 97 mustang v6 the temp gauge is all the way over on hot. After I drive for about 30 miles it will go to a random place in the normal range, however as soon as i start up the car it pegs again. I've done a coolant flush, changed both of the coolant sensors and the tstat. Where do i go next? could it be a bad ground wire? Seems like the readings from the multimeter into the sensors dont make much sense they are all over the place. However visual inspection of the wires looks fine? Im lost. I dont want to pull the gauge cluster unless i have too. Thanks
 

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08GT500

Active Member
Jul 12, 2018
620
76
38
Massachusetts
So i have a 97 mustang v6 the temp gauge is all the way over on hot. After I drive for about 30 miles it will go to a random place in the normal range, however as soon as i start up the car it pegs again. I've done a coolant flush, changed both of the coolant sensors and the tstat. Where do i go next? could it be a bad ground wire? Seems like the readings from the multimeter into the sensors dont make much sense they are all over the place. However visual inspection of the wires looks fine? Im lost. I dont want to pull the gauge cluster unless i have too. Thanks
Hi,
As no overheating nor drivability issues are being reported(?), issue is sender, gauge, wire, or plug. Verify Coolant full & sys.air free.
1) Key on, Inspect, slowly wiggle test the plug while another views the gauge.
2) Disconnect the sender’s plug & key on. If it pegs, it a wiring or gauge issue.
3) Senders are variable resistors, higher gauge readings indicate higher resistance to ground, colder indicates less.
4) Sender unplugged, check resistance between the sender’s pin & Ground (Block) with a VOM. Should read about 140 Ohms Cold, 30-50 Ohms Hot, if memory serves.
Good luck!
- John
 

08GT500

Active Member
Jul 12, 2018
620
76
38
Massachusetts
Hi,
As no overheating nor drivability issues are being reported(?), issue is sender, gauge, wire, or plug. Verify Coolant full & sys.air free.
1) Key on, Inspect, slowly wiggle test the plug while another views the gauge.
2) Disconnect the sender’s plug & key on. If it pegs, it a wiring or gauge issue.
3) Senders are variable resistors, higher gauge readings indicate higher resistance to ground, colder indicates less.
4) Sender unplugged, check resistance between the sender’s pin & Ground (Block) with a VOM. Should read about 140 Ohms Cold, 30-50 Ohms Hot, if memory serves.
Good luck!
- John
Edit: #3) Higher (Hotter) GAUGE readings indicate LOWER resistance values, Colder indicates HIGHER resistance values. My bad.
- John