87 supra turbo temp gauge prob

[bill928]

i have a 87 toyota supra turbo ,while driving it the temp gauge jumped up to hot. i pulled over and turned the car off.the car was not overheating at all,nothing was hot. I let the car sit for about an hour, the car was cold,radiator cold to touch,but when i turned the ignition to accessories, the needle went straight up to hot and now every time i turn the car on the gauge goes right up to hot and stays there until the key is turned off and then it drops. I would appreciate any help with this,thanks.

[toyomoho]

Check the gage wiring to see if it is grounded at some point.

[Midnight87]

might be a bad sending unit, that same situation occured
with a '77 Celica I owned several years ago. replaced the
unit, wired it up and it was fine ...

[Jeeves]

The temp sending unit is a big, brown, two wire plug on the thermostat housing. Wiggle it and make sure it's good to go, other than that, sounds like a short somewhere.