Temp Gauge

[REDROCKER652002]

Thanks to all who helped me out with the gas gauge issue. We have seem to run into another issue, this time with the temp gauge. I am going to try my best to post some numbers and ohm readings that I did. My initial reaction is it is the gauge, but looking for any help.

Ok, here goes:

Original gauge into a new American Auto Wire stock plug. All wires and grounds seem to be working. Bench test of the dash first. New Circuit board as well.

OK, so I lay the dash on it's face on my work bench with the posts from the Temp gauge facing up.

Ohm Meter set on 200 and I proceed. Put the tester leads on the left and right posts. Positive on the left, Negative on the right. 50ohms. Switch the tester probes, still 50ohms.

Positive on the left negative on the top post 115ohms

Positive on the right Negative on the top post 60ohms

Ok, now I plug the dash into the harness. 132ohms when I touch the green wire in the clip and ground out the tester

I put the hot lead on the left post of the gauge and ground the tester 111ohms

I put the hot lead on the right post of the gauge and ground the tester 64ohms

I then touch both left and right while the harness is plugged in and I get about 46ohms

All testing of the dash in the truck were done with the truck running.

The needle on the gauge has not moved, hence why I am leaning towards the gauge.

Also, I bought a new sending unit before I did all this as the one that was in there was pretty badly rusted and chewed up. Thought I would start there an move up.

Thanks to all who took the time to read all of this, and any input would be most appreciated. This is the last part of the dash that I need to get working so my son can go back to the original dash setup that he would like to have for now.

thanks again.

RR

[REDROCKER652002]

Bump in the hope it just got buried. Any comments or suggestions would be most appreciated.

[randy500]

Grounding the temp sensor wire should peg the guage to “hot” if no reaction then either the wiring or the guage is bad.

Test the sensor wire at the guage panel in ohms, is it nearly the same as the sensor at the engine?

I think i remember you have a myriad of repro and mis-installed parts....

The gauge itself installs in the metal backing plate with plastic insulators on the 2 mounting studs which are power and sensor, maybe the gauge was installed without the insulators?
The bottom terminal of the guage also has to be grounded to the metal backing plate through a star washer under the ceramic resistor, is it missing?

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

[70LonghornCST]

Originally Posted by randy500

Grounding the temp sensor wire should peg the guage to “hot” if no reaction then either the wiring or the guage is bad.

Test the sensor wire at the guage panel in ohms, is it nearly the same as the sensor at the engine?

I think i remember you have a myriad of repro and mis-installed parts....

The gauge itself installs in the metal backing plate with plastic insulators on the 2 mounting studs which are power and sensor, maybe the gauge was installed without the insulators?
The bottom terminal of the guage also has to be grounded to the metal backing plate through a star washer under the ceramic resistor, is it missing?

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

check the ceramic resistors. That may the issue if everything points back to the gauge.

[REDROCKER652002]

Originally Posted by randy500

Grounding the temp sensor wire should peg the guage to “hot” if no reaction then either the wiring or the guage is bad.

Test the sensor wire at the guage panel in ohms, is it nearly the same as the sensor at the engine?

I think i remember you have a myriad of repro and mis-installed parts....

The gauge itself installs in the metal backing plate with plastic insulators on the 2 mounting studs which are power and sensor, maybe the gauge was installed without the insulators?
The bottom terminal of the guage also has to be grounded to the metal backing plate through a star washer under the ceramic resistor, is it missing?

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

Thanks for the info, I don't think it is me who has the myriad though. LOL. New wiring, but supposed to be stock in nature from AAW. Other than that, all stock.

Great info though, I will look and see what is under everything. As far as I know, it has never been touched. But I don't know for sure. So this is all good info.

Thanks for the reply. RR

[REDROCKER652002]

Originally Posted by 70LonghornCST

check the ceramic resistors. That may the issue if everything points back to the gauge.

Will do, thanks for the info. I am thinking of just buying a new gauge. I think they are only about 20 bucks, and it takes that out of the equation. But I will check it. Thanks.

[REDROCKER652002]

OK. Son has the truck, but he is using an aftermarket three gauge cluster for now, so the dash and all is here. I took the gauge off the cluster to take a look. Ceramic resistor is pretty bugged up where it touches the back of the plate, so I took some steel wool to it. Don't see any washers between the ceramic piece and the backing plate, but my question is, wouldn't it show bad when I put the Ohm meter on it on the bench? Maybe not, because I am grounding it using the gauge. I am killing time and having a beer, so this is just me screwing around until the kid gets home. LOL Thanks to all who replied