Temp gauge pegged full hot? Here is the fix

[TBONE1964]

It has been covered before but I thought I would cover it again. It has come to my attention with some of my cluster builds that the temp gauge is pegging full hot once installed.

For this reason, I have changed my method of testing gauges for cluster builds.

If you test a temp gauge out of the cluster, you have to ground the lower center terminal on the gauge. Once the gauge is installed in the tin and then into the cluster, the gauge relies on grounding through the tin. From the factory, they used a one way push on retainer that had two purposes. It held the gauge in place for assembly and also it acted as a ground from the gauge to the tin.

Once the cluster is installed in the dash and the connector pluged in, it is possible that the gauge will peg full hot because the lower center terminal is not grounded.

The simple fix is to make a short ground strap and install it as shown in the photo I have attached. It can be made of 14 gauge wire with eyelets on both ends or a short braided ground strap. With either option the eyelet size is a #6.

Please let me know if you have any questions on this. I understand it has been discussed and covered in the past but wanted to update this.

All of my future cluster builds will include this ground wire to prevent any issues after cluster installation.

Take care,
Tom

[jtinpdx]

Originally Posted by TBONE1964

It has been covered before but I thought I would cover it again. It has come to my attention with some of my cluster builds that the temp gauge is pegging full hot once installed.

For this reason, I have changed my method of testing gauges for cluster builds.

If you test a temp gauge out of the cluster, you have to ground the lower center terminal on the gauge. Once the gauge is installed in the tin and then into the cluster, the gauge relies on grounding through the tin. From the factory, they used a one way push on retainer that had two purposes. It held the gauge in place for assembly and also it acted as a ground from the gauge to the tin.

Once the cluster is installed in the dash and the connector pluged in, it is possible that the gauge will peg full hot because the lower center terminal is not grounded.

The simple fix is to make a short ground strap and install it as shown in the photo I have attached. It can be made of 14 gauge wire with eyelets on both ends or a short braided ground strap. With either option the eyelet size is a #6.

Please let me know if you have any questions on this. I understand it has been discussed and covered in the past but wanted to update this.

All of my future cluster builds will include this ground wire to prevent any issues after cluster installation.

Take care,
Tom

Thanks for all of your contributions, Tom! Awesome to have you on here.

-Jeff

[TBONE1964]

Originally Posted by jtinpdx

Thanks for all of your contributions, Tom! Awesome to have you on here.

-Jeff

Hi Jeff, Thank you as well. I am glad your temp gauge issues are resolved and everything is working. It is my pleasure to help those that would be reluctant to do it themselves.

Take care,
Tom

[VetteVet]

Here's a picture to confirm your post Tom. I will add that the wire from the sending unit will also cause the gauge to go hot if it gets shorted to ground. Thanks Tom for your pics and advice. Great job.

[TBONE1964]

Originally Posted by VetteVet

Here's a picture to confirm your post Tom. I will add that the wire from the sending unit will also cause the gauge to go hot if it gets shorted to ground. Thanks Tom for your pics and advice. Great job.


Attachment 1320848



Attachment 1320847

As always Vette, your advise is a great addition to anyone who has electrical problems. Thanks you for your added information on this as it will help others with temp gauge issues.

Take care,
Tom

[Daddy'O]

Good job Tom and VetteVet -

This very problem almost whipped my butt a couple of years ago.

[TBONE1964]

Originally Posted by Daddy'O

Good job Tom and VetteVet -

This very problem almost whipped my butt a couple of years ago.

Hi Wayne,

As funny as it may seem (or not funny) you may want to add ground straps on the clusters I built for you. Just to be on the safe side. It seems to be about 50/50 as if the temp gauge will work correctly with out it.

I am also trying to locate the correct push on retainers that the factory used. It would look much better than the ground strap but in a pinch the strap works well and does its job.

Hope all is well in TX and thank you for your contributions to this issue.

Take care,
Tom

[Daddy'O]

Hey Tom –

I had no luck finding the retainers either. I was lucky to have had a couple of trashed out clusters when I repaired the “restored” clusters I bought from another member a couple of years ago. I’m hoping to install one of the clusters I got from you into Nancy before Thanksgiving. I’ll take your advice and install the jumper to be on the safe side.

All is well here in Texas – Hoping all is well up in the great North West!

[elf w/capital T]

Tom, you sir are awesome, had my project running at idle and temp gauge was pegged, I knew I had the tin grounded but doing the little jumper is way better than the little retainer clip/washer. Plus. I got the battery gauge, your workk is great! Thanks!

[shawno72]

Great info as always. Thank you!

[dirish]

I know it's an old post but I spent all day putting a brand new cluster in and the temp pegged out hot. Knowing it wasnt. I searched a few minutes to find this post, took me about 10 minutes to fix my cluster! thank you very much!!

[TBONE1964]

Originally Posted by dirish

I know it's an old post but I spent all day putting a brand new cluster in and the temp pegged out hot. Knowing it wasnt. I searched a few minutes to find this post, took me about 10 minutes to fix my cluster! thank you very much!!

GREAT!!! Glad it helped you.

Take care,
Tom

[dirish]

Originally Posted by TBONE1964

GREAT!!! Glad it helped you.

Take care,
Tom

Hey Tom, searching. .... can I do that with gas gauge.
It was fine till I changed clusters todY. Can I use bottom pin and ground like temp guage?
Thanks in advance!

[TBONE1964]

Originally Posted by dirish

Hey Tom, searching. .... can I do that with gas gauge.
It was fine till I changed clusters todY. Can I use bottom pin and ground like temp guage?
Thanks in advance!

What exactly is the gauge doing now? How much gas is in the tank? Do you have a ohm/volt meter?

Let me know and I can walk you through finding the cause. How does everything else on the cluster work? Lights, temp gauges , turn signal indicators?

And yes you can ground from that center lug on the fuel gauge. Very rarely is ground an issue on the cluster if other things are working OK.

Double check the connector and circuit board where it plugs in. Make sure all of the brass contact are in the correct position and none of them are touching or folded over onto another. You can use super glue to put them back into position if needed.

Hope this helps,
Tom

[a1vintage69]

Originally Posted by TBONE1964

GREAT!!! Glad it helped you.

Take care,
Tom

Hi Tom, This question is off subject but thought I would ask because I know a lot of guys will be interested. Do you restore the chrome on wood grain bezels or know anybody that does? Mine is faded down to the black in spots and all the nos bezels with wood grain are silver and not chrome. I would also be interested in a good original chrome wood grain bezel if you ever sell any. I just bought a speedminder/tach/vacum cluster from a member today and may want to restore it to good driver quality with my wood grain bezel for my Super. I would like to know what an average restore could cost just a ball park guess. any help will be much appreciated. thank you, Steve

[TBONE1964]

Originally Posted by a1vintage69

Hi Tom, This question is off subject but thought I would ask because I know a lot of guys will be interested. Do you restore the chrome on wood grain bezels or know anybody that does? Mine is faded down to the black in spots and all the nos bezels with wood grain are silver and not chrome. I would also be interested in a good original chrome wood grain bezel if you ever sell any. I just bought a speedminder/tach/vacum cluster from a member today and may want to restore it to good driver quality with my wood grain bezel for my Super. I would like to know what an average restore could cost just a ball park guess. any help will be much appreciated. thank you, Steve

Hi Steve,

I will send you a PM with details.

Take care,
Tom

[dirish]

I had to grouND temp. All else works good. I will heck my plug when I get home. Thank You!

[68 Greenie]

This issue has been kicking my butt for weeks. I just did what tbone1964 said and seems to have fixed the problem. Thank you very much.

[TBONE1964]

Originally Posted by 68 Greenie

This issue has been kicking my butt for weeks. I just did what tbone1964 said and seems to have fixed the problem. Thank you very much.

Glad it helped you.

Thank you,
Tom

[blazer2007]

does this apply too 75 ish clusters?

[ray_mcavoy]

Originally Posted by blazer2007

does this apply too 75 ish clusters?

Sort of. By that, I mean the 73+ temp gauges will peg full hot (just like the 67-72 temp gauges) if they have a bad ground connection. But the design of the 73+ clusters is different (they have a plastic housing instead of metal). So the fix of adding a ground wire as shown here doesn't directly apply to the 73+ clusters. All of the gauge connections (including the ground) in the 73+ clusters make use of springy metal clips to connect the studs on the backs of the gauges to the traces on the cluster's printed circuit. Sometimes those clips get a little bit of corrosion on them and no longer make good contact with the printed circuit and that could cause a bad ground at the temp gauge.

Another thing that can cause the temp gauge to peg full hot is a sending unit wire that has shorted to ground. So it's a good idea to carefully check the wire (usually dark green) that connects to the temp sending unit to make sure it hasn't melted against the exhaust, hasn't been pinched, chafed, or otherwise shorted to ground anywhere.

[TBONE1964]

Originally Posted by ray_mcavoy

Sort of. By that, I mean the 73+ temp gauges will peg full hot (just like the 67-72 temp gauges) if they have a bad ground connection. But the design of the 73+ clusters is different (they have a plastic housing instead of metal). So the fix of adding a ground wire as shown here doesn't directly apply to the 73+ clusters. All of the gauge connections (including the ground) in the 73+ clusters make use of springy metal clips to connect the studs on the backs of the gauges to the traces on the cluster's printed circuit. Sometimes those clips get a little bit of corrosion on them and no longer make good contact with the printed circuit and that could cause a bad ground at the temp gauge.

Another thing that can cause the temp gauge to peg full hot is a sending unit wire that has shorted to ground. So it's a good idea to carefully check the wire (usually dark green) that connects to the temp sending unit to make sure it hasn't melted against the exhaust, hasn't been pinched, chafed, or otherwise shorted to ground anywhere.

Good advise

[JoePolo]

Tom brining this old one back to see if you can help me. My temp gauge is pegged with the key off/battery disconnected. I have photos of the cluster in the truck and after I added the clock and the gauge is in the normal place. When I first started the truck, I actually forgot to hook up the sender wire. I found your post and ran a jump with alligator clips as shown and also directly to the column brace on the dash, with no change on the gauge. I am going to ohm the sender wire today, but with it staying in the pegged position even with the power off I am going to assume that the gauge is bad/stuck.

Thanks Tom.