How to check engine temperature warning lights

[August65C10]

Originally Posted by bloo

Something is not right.

There should be a sending unit on the engine with 2 pins. If you unplug it, with the key on, and you ground one wire, the hot light should come on. If you ground the other wire, the cold light should come on.

When you turn the key all the way to start, the hot light should come on to check the bulb. I don't think the cold light ever gets checked.

The sockets for the bulbs can sometimes get stuck in the wrong holes in the instrument cluster. The hot light has a red socket and the cold light has a black one.

Also, have a look at this thread: http://67-72chevytrucks.com/vboard/s...d.php?t=789198
On that truck the wiring harness was wrong.

Thanks a lot bloo!
I didn´t know that the hot light should be checked while cranking the engine. Something is not correctly wired. The post on the link has great info too. I´m going to check the wiring today. Thanks!