new circuit board no temp gauge operation - The 1947 - Present Chevrolet & GMC Truck Message Board Network

elorenzof · 11-08-2020, 11:32 PM

I just replaced a burnt circuit board and decided to tear down and paint tins while i had the cluster out of the truck. Now rebuilt and looking great but my temp gauge (new gauge) needle is so far to the left you can't see it. Can someone help? Thank you.

**pjmoreland** · 11-09-2020, 11:40 AM

Was your temp gauge working before you replaced the circuit?

Did you install your new temp gauge along with the circuit, or was the new gauge installed previously and was functional?

Did you reinstall the gauge resistor, as shown in the photo?

elorenzof · 11-09-2020, 11:53 AM

Quote:

Originally Posted by pjmoreland

Was your temp gauge working before you replaced the circuit?

Did you install your new temp gauge along with the circuit, or was the new gauge installed previously and was functional?

Did you reinstall the gauge resistor, as shown in the photo?

Yes, the temp gauge was working beforehand.

I rebuild the cluster, it has all new gauges along with the new circuit.

Yes, the resister is installed as well i took pics during dis-assembly to help with re-assembly.

**pjmoreland** · 11-09-2020, 12:08 PM

Maybe you have a grounding issue since you repainted the tins. There is an image in the following post that shows what each terminal on the gauge is for. You could try adding a separate temporary ground to the ground post to see if that wakes up the gauge.

https://67-72chevytrucks.com/vboard/...ght=Temp+gauge

elorenzof · 11-09-2020, 01:37 PM

Quote:

Originally Posted by pjmoreland

Maybe you have a grounding issue since you repainted the tins. There is an image in the following post that shows what each terminal on the gauge is for. You could try adding a separate temporary ground to the ground post to see if that wakes up the gauge.

https://67-72chevytrucks.com/vboard/...ght=Temp+gauge

That makes sense. I will try the ground suggestion. Thank you!

70StepsideC10 · 11-09-2020, 02:14 PM

I'm no gauge expert, but I think this might mean you have an open on the sender terminal of the gauge. With the stock senders, as temperature increases sender resistance to ground decreases and the gauge moves to hot. So if the gauge is on the cold side then you would be getting a high resistance to ground, or an open circuit from the sender. Have you tried putting a ground on the sender terminal to see if the gauge moves? It should peg to full hot with a solid ground.

elorenzof · 11-12-2020, 12:39 PM

OK, I looked under my OTHER truck, a 70 C10 and it has a blue resistor on the temp gauge. (photo) but on the one i unsuccessfully rebuilt and that we are talking about, i stuck my head under there and when i put it back together i put on a little white resistor, (which i thought it had, apparently no pic on my phone to refer to). So i had another blue resistor and managed to put it on w/o pulling the dash again and now it's pegged to the right (past hot) when it was originally pegged below cold. It is an aftermarket gauge from LMC not the original as it was extremely faded and old and rusted. I noticed on the pic with the blue resistor there is a long nut on each end where the circuit board mount to that goes against the gauge, then the circuit board, then the final washer and nut to finish it off. but the new temp gauge the terminals arent that long so i couldnt put the widened long nuts on would that make a difference in anything? any help again would be appreciated. sorry for the long story.

**pjmoreland** · 11-12-2020, 01:40 PM

Hey, well at least now you know your gauge is capable of moving. Maybe the new resistor you installed has the wrong resistance. Do you have a multimeter? That link I posted previously says the resistance should be 90 Ohms. You'll likely need to remove the resistor to get a valid reading so that the resistor is the only thing you're measuring.

I have a 67 cluster and a newer 69-72 cluster laying around. The 67 has the spiral wrapped resistor and no spacers, and the newer one has the spacers like on your 70.

Before you replaced the resistor, did you try 70StepsideC10's suggestion of connecting the terminal on the passenger side of the gauge to ground to see if the needle would peg hot?

70StepsideC10 · 11-13-2020, 11:19 AM

There should be little plastic sleeves on the left and right studs (the ones that the circuit board connect to), where they pass through the metal housing to keep them from shorting to the housing. When you installed the new gauge, did you install the sleeves? If not it is possible the sender stud has shorted to the metal housing which would cause the gauge to peg to hot.
Posted via Mobile Device

11-08-2020, 11:32 PM	#1
elorenzof Registered User Join Date: Nov 2017 Location: Anthem AZ Posts: 281	new circuit board no temp gauge operation I just replaced a burnt circuit board and decided to tear down and paint tins while i had the cluster out of the truck. Now rebuilt and looking great but my temp gauge (new gauge) needle is so far to the left you can't see it. Can someone help? Thank you.

11-09-2020, 11:40 AM	#2
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,981	Re: new circuit board no temp gauge operation Was your temp gauge working before you replaced the circuit? Did you install your new temp gauge along with the circuit, or was the new gauge installed previously and was functional? Did you reinstall the gauge resistor, as shown in the photo? Attached Images

11-09-2020, 12:08 PM	#4
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,981	Re: new circuit board no temp gauge operation Maybe you have a grounding issue since you repainted the tins. There is an image in the following post that shows what each terminal on the gauge is for. You could try adding a separate temporary ground to the ground post to see if that wakes up the gauge. https://67-72chevytrucks.com/vboard/...ght=Temp+gauge

11-09-2020, 02:14 PM	#6
70StepsideC10 Registered User Join Date: Jul 2016 Location: Toronto, Ontario Posts: 39	Re: new circuit board no temp gauge operation I'm no gauge expert, but I think this might mean you have an open on the sender terminal of the gauge. With the stock senders, as temperature increases sender resistance to ground decreases and the gauge moves to hot. So if the gauge is on the cold side then you would be getting a high resistance to ground, or an open circuit from the sender. Have you tried putting a ground on the sender terminal to see if the gauge moves? It should peg to full hot with a solid ground.

11-12-2020, 12:39 PM	#7
elorenzof Registered User Join Date: Nov 2017 Location: Anthem AZ Posts: 281	Re: new circuit board no temp gauge operation OK, I looked under my OTHER truck, a 70 C10 and it has a blue resistor on the temp gauge. (photo) but on the one i unsuccessfully rebuilt and that we are talking about, i stuck my head under there and when i put it back together i put on a little white resistor, (which i thought it had, apparently no pic on my phone to refer to). So i had another blue resistor and managed to put it on w/o pulling the dash again and now it's pegged to the right (past hot) when it was originally pegged below cold. It is an aftermarket gauge from LMC not the original as it was extremely faded and old and rusted. I noticed on the pic with the blue resistor there is a long nut on each end where the circuit board mount to that goes against the gauge, then the circuit board, then the final washer and nut to finish it off. but the new temp gauge the terminals arent that long so i couldnt put the widened long nuts on would that make a difference in anything? any help again would be appreciated. sorry for the long story. Attached Images

11-12-2020, 01:40 PM	#8
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,981	Re: new circuit board no temp gauge operation Hey, well at least now you know your gauge is capable of moving. Maybe the new resistor you installed has the wrong resistance. Do you have a multimeter? That link I posted previously says the resistance should be 90 Ohms. You'll likely need to remove the resistor to get a valid reading so that the resistor is the only thing you're measuring. I have a 67 cluster and a newer 69-72 cluster laying around. The 67 has the spiral wrapped resistor and no spacers, and the newer one has the spacers like on your 70. Before you replaced the resistor, did you try 70StepsideC10's suggestion of connecting the terminal on the passenger side of the gauge to ground to see if the needle would peg hot?

11-13-2020, 11:19 AM	#9
70StepsideC10 Registered User Join Date: Jul 2016 Location: Toronto, Ontario Posts: 39	There should be little plastic sleeves on the left and right studs (the ones that the circuit board connect to), where they pass through the metal housing to keep them from shorting to the housing. When you installed the new gauge, did you install the sleeves? If not it is possible the sender stud has shorted to the metal housing which would cause the gauge to peg to hot. Posted via Mobile Device



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