I've been reading around and can't find any concrete info on why the SR5 temp gauge jumps to operating temp as soon as the key is turned on. I've tried replaced the temp gauge sender, and tried 2 different SR5 instrument clusters... same thing every time.

Has anyone solved this? If not, for folks who have this same issue do you know if the temp gauge will read above normal operating temp if you do in-fact start to overheat?

Thanks

 

This worked for me:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

Hint: It is not the gauge and it is not the sender.

 

4Crawler... thanks for your quick response. Could it still be a thermostat issue even if the temp gauge goes to OP when the car is not running, or just started? If it was the thermostat my guess is that it would read cool for at least a couple minutes before shooting up, right?

Thanks

 

Mine would shoot up in maybe a minute of driving, but not right away. I suppose you could try testing the sender to see if it is putting out an off nominal resistance. Could also be some other electrical issue like a ground problem or something else aside from the sender and gauge, since you say it happens with multiple units. Could be some sort of partial/intermittent short, since the sender resistance falls with increasing temp. And are you changing out the correct sender, the one on the passenger side of the head?

 

Yes, that is the sender that I changed. When I first changed it I thought I'd fixed the problem. Unplugged the old sender, turned the key, temp gauge didn't move. Sender problem right? So i changed the sender and started the truck (cold) temp gauge stayed at the bottom for about 15 seconds, then right back up to the same place. Now it does this every time.

 

Suppose you could try hooking the spare sender up to the wire harness and be sure to ground the threaded part and see if it does the same thing with it not in the coolant. If so, that would pretty much rule out a faulty sender. Or hook up a ~100 ohm resistor to the wire harness and ground and that should give a sort of middle range reading on the gauge. Run the engine and see if the gauge reading varies, it should not since the resistor is fixed in value.