92 Sedan - Temp Guage reading high - Toyota Nation Forum : Toyota Car and Truck Forums

Ranchpig · 05-11-2009, 03:57 PM

Just picked up a used 92 sedan and the temp guage is reading high.

Pulled wire from sending unit and guage goes back to zero. When starting cold it will read 1/4 hot and Rapidly move to highest setting.

Put an Ohm meter on the sending unit on 2000 setting and with a lighter on end it goes to 0 fairly quickly... letting it air cool it will move into the 1000's reasonably slowly.

I bought a new one thinking it might be out of whack... because i have no specs on the ratings. It does the same thing. However, i left the new one in the vehicle let it run for 5 minutes and checked the resistance and it was around 100 on a 2000 scale. That would indicate it's running incredibly hot and the guage is fairly accurate, right?

any help would be appreciated.

90 GP · 05-11-2009, 05:06 PM

Are the electric cooling fans by the radiator running when the temp gauge gets slightly past the midway point? They should kick on and shut off when gauge goes back to midway. Also check thermostat,water pump and radiator.

patcal · 05-11-2009, 05:53 PM

I would get a candy thermometer and put it into the radiator and let it idle until the fan comes on. Start the engine cold. It should come on at 200F. The fan should come on when the connector is unplugged from the sensor on the thermostat housing when it is cold. If not you have a fan circuit issue.

fistofmeat · 05-11-2009, 06:57 PM

check the thermostat, i hear they get stuck often on these cars. mine had a similar problem a while back, replaced the thermostat (less than 10 bucks and half an hour of work) and i was good to go.

***REN69*** · 05-12-2009, 02:40 AM

Mine was stuck open and wouldn't heat up, in this case it looks like it's stuck on the closed position so your coolant never goes through the system.

Ranchpig · 05-12-2009, 02:46 PM

Thanks for the tips... i'll try those things and get back. I know the fan will come on... not sure the temp though. I thought if i took the cap off it would start spilling out. I can unplug the fan sensor and cause the fan to come on. From a cold start the temp guage rapily starts to climb. I would think too fast for the t-stat to cause that. I found the resistance stats for the guage. I know there is another way to check the guage itself and that would be to put a set resistance inline and that "Should" give an idea where the guage is. But that would require a trip to radio shack. I'll keep plugging away.

90 GP · 05-12-2009, 03:22 PM

I hate to bring up another possiblilty but what about a blown head gasket? How does the car run? Have you seen any oil in the antifreeze or vice versa?

Flashmn · 05-12-2009, 05:21 PM

You did realize that the fans and the gauge run from different sending units, right?

Ranchpig · 05-15-2009, 04:52 PM

Well... i used a thermometer and the fan DOES come on at just under 200. So the fan sensor is working properly. I replaced the t-stat and that had no effect at all.

So..... either my aftermarket gauge sensor is not calibrated in resistance for the gauge itself or the gauge is faulty. I read in another post that the clusters go bad sometimes and another hint was to check the grounding of the cluster. How would i do that exactly? I know i'm getting 12v to the temp sensor (gauge one).

I hope it's not my cluster and if it is... how hard is it to find a replacement?
Would throwing in an aftermarket temp sensor/gauge be better?