Temp Sender

[farmallboy15]

So my root problem is that the temp gauge pegs hot and stays there. From my reading, pegging means there is a short to ground somewhere. I have a new gauge and a new connector for the sender. I don't believe there to be any breaks in the wire leading to the sender and have voltage to the sender.

With that said, I am having trouble with senders unless I am wrong.

My old sender reads .5 ish ohms cold. 150 or so hot. After testing 3 NEW senders, from 2 different stores, they all read the same cold!!??

Shouldn't they read in the 600 range cold and as they heat up resistance goes down, giving the gauge a better ground, making the needle go to the hot side!?

Thanks for the help. This truck has been nothing but problems but hopefully it is nice when it's finished... I'm getting there... Slowly...

[TBONE1964]

Originally Posted by farmallboy15

So my root problem is that the temp gauge pegs hot and stays there. From my reading, pegging means there is a short to ground somewhere. I have a new gauge and a new connector for the sender. I don't believe there to be any breaks in the wire leading to the sender and have voltage to the sender.

With that said, I am having trouble with senders unless I am wrong.

My old sender reads .5 ish ohms cold. 150 or so hot. After testing 3 NEW senders, from 2 different stores, they all read the same cold!!??

Shouldn't they read in the 600 range cold and as they heat up resistance goes down, giving the gauge a better ground, making the needle go to the hot side!?

Thanks for the help. This truck has been nothing but problems but hopefully it is nice when it's finished... I'm getting there... Slowly...

So did the new sender(s) fix your pegging problem on the gauge? Did you check the old temp sender with the same meter you tested the new one (s) with?

It sounds to me like you meter is not calibrated correctly. The gauge should only peg if the green wire is grounded or the temp sender is shorted out internally. Also it can be shorted to ground against the tin that holds the gauge.

[farmallboy15]

Originally Posted by TBONE1964

So did the new sender(s) fix your pegging problem on the gauge? Did you check the old temp sender with the same meter you tested the new one (s) with?

It sounds to me like you meter is not calibrated correctly. The gauge should only peg if the green wire is grounded or the temp sender is shorted out internally. Also it can be shorted to ground against the tin that holds the gauge.

It is still pegging. Same meter. I do trust this meter, but it could be off.. Right now I'm just trying to get a sender that works then I can make sure the wire and the rest of the system is good...

Am I correct in thinking as to how it all works and the resistance the sender should show on its own?

[TBONE1964]

Originally Posted by farmallboy15

It is still pegging. Same meter. I do trust this meter, but it could be off.. Right now I'm just trying to get a sender that works then I can make sure the wire and the rest of the system is good...

Am I correct in thinking as to how it all works and the resistance the sender should show on its own?

"Shouldn't they read in the 600 range cold and as they heat up resistance goes down, giving the gauge a better ground, making the needle go to the hot side!?"

Yes, this is correct thinking. That is why I questioned your meter. The cooler the temp sender the higher the resistance value. 70 degrees F should be around 610 ohms, 212 degrees F should be around 80 ohms.

If your needle is pegging, the green wire is finding ground, the sender is shorted to ground or the stud on the gauge is grounded to the tin.

Try and disconnect the green wire from the sender. If you do that does the gauge still peg?

This may take some trial and error to diagnose and help you figure out. Let me know what happens if the green wire is not hooked to the temp sender.

[Daddy'O]

Tom is correct on all counts. Let me add this to your check list:

http://67-72chevytrucks.com/vboard/s...d.php?t=545902

[TBONE1964]

Originally Posted by Daddy'O

Tom is correct on all counts. Let me add this to your check list:

http://67-72chevytrucks.com/vboard/s...d.php?t=545902

Thank you Wayne,

The thread you linked has great information and visuals to help. Thanks also to VetteVet for his illustrations.

Take care,
Tom

[Daddy'O]

You’re welcome Tom.

Problems like this are extremely frustrating. If our information helps one person then I think it’s worth sharing.

[farmallboy15]

Update: I'm an idiot... lol. I didn't see the k on the volt meter... k, kilo, one thousand. .58 x 1000 =580 ohms at 80 degrees, about right. Next. Checked the resistance in the wire. 0 ohms, again, good. So I'm down to something in the dash. It looks like that thread you sent should help alot! Thanks again! I'll post back with the end result.

[farmallboy15]

Thanks guys! Ran the ground wire that was described in Daddy'os thread and it worked like a charm!

[farmallboy15]

Now if only I knew why all my rear lights work except the flashers... The rear turn signals work just not the flashers... Sounds like something under the dash.

[TBONE1964]

Originally Posted by farmallboy15

Now if only I knew why all my rear lights work except the flashers... The rear turn signals work just not the flashers... Sounds like something under the dash.

Do they work on the dash or the front?

[farmallboy15]

Originally Posted by TBONE1964

Do they work on the dash or the front?

The flashers work on both the dash and the front lights. Just not the rear.. Are there possibly two relays in the flasher relay?