1972 k20 gauge problems. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

low1954 · 03-06-2015, 09:23 AM

I have a 1972 chevy k20 that is still somewhat
New to me. I have been making updates to the
Trucks suspension as well as cab weather stripping, and have installed a
Tachometer. I had noticed when driving the truck home to Washington
From California that the amp gauge really didn't move, and even with
The truck turned off and battery disconnected it still read the same. I had also had intermittent problems with the temp gauge being sporadic, and now just pegged at all times, even with the battery disconnected. I have now
Ordered a three gauge cluster, for accurate readings, but still would
Like to figure out what's going on with the stock amp and temp gauge.
The green wire is connected to the sensor on the manifold, and I traced it into the wire harness over on the passenger side of the truck down by the starter. I would assume that it goes into the harness and into the cab to the gauge cluster? And was wondering if the wire is still green in color, of I need to trace a
Ground issue? Any and all help would be awesome. Thanks Jeremy

farmallboy15 · 03-06-2015, 10:09 AM

I had the same problem with the temp gauge. Thought it was the gauge or the sensor. There is a trouble shooting guide somewhere if you search for it. I know it is in one of my threads if you search my name... also there is a wiring diagram on a website if you Google "outintheshop" he has lots of guides and makes spid labels.

Bottom line. Run a ground wire from the back side of the gauge panel to a clean ground under the dash. Sorry I can't help with the rest of the gauges...

**LockDoc** · 03-06-2015, 10:29 AM

-

Nice truck &

to the board.

Here is a picture of where the stock gauge cluster ground is attached. The amp gauge never moves much, if at all. There are two 4 amp fuses that are wired into the gauge circuit, one on each side of the core support. Second picture is what they look like. Sometimes the fuses are corroded or broken.

57taskforce · 03-06-2015, 10:36 AM

Sorry I can't be much help with the gauges, but man that's a nice looking truck!

low1954 · 03-07-2015, 12:02 AM

Thanks everyone for all the help, I will cram myself
Under the dash this weekend to hopefully find the problem. Thanks again!!

RAMMER · 07-12-2015, 12:22 PM

HI LOCKDOC
I am sending you some pictures of the circuit board ,it seems to have a cut on it would this be my problem?.
CHEERS RAMMER

**LockDoc** · 07-12-2015, 12:48 PM

Quote:

Originally Posted by RAMMER

HI LOCKDOC
I am sending you some pictures of the circuit board ,it seems to have a cut on it would this be my problem?.
CHEERS RAMMER

It certainly could be if it is cut all the way through the copper ribbon imbedded in the circuit board....

LockDoc

03-06-2015, 09:23 AM	#1
low1954 Registered User Join Date: Jun 2014 Location: Washington Posts: 26	1972 k20 gauge problems. I have a 1972 chevy k20 that is still somewhat New to me. I have been making updates to the Trucks suspension as well as cab weather stripping, and have installed a Tachometer. I had noticed when driving the truck home to Washington From California that the amp gauge really didn't move, and even with The truck turned off and battery disconnected it still read the same. I had also had intermittent problems with the temp gauge being sporadic, and now just pegged at all times, even with the battery disconnected. I have now Ordered a three gauge cluster, for accurate readings, but still would Like to figure out what's going on with the stock amp and temp gauge. The green wire is connected to the sensor on the manifold, and I traced it into the wire harness over on the passenger side of the truck down by the starter. I would assume that it goes into the harness and into the cab to the gauge cluster? And was wondering if the wire is still green in color, of I need to trace a Ground issue? Any and all help would be awesome. Thanks Jeremy Attached Images

03-06-2015, 10:09 AM	#2
farmallboy15 Registered User Join Date: May 2014 Location: Lancaster, OH Posts: 81	Re: 1972 k20 gauge problems. I had the same problem with the temp gauge. Thought it was the gauge or the sensor. There is a trouble shooting guide somewhere if you search for it. I know it is in one of my threads if you search my name... also there is a wiring diagram on a website if you Google "outintheshop" he has lots of guides and makes spid labels. Bottom line. Run a ground wire from the back side of the gauge panel to a clean ground under the dash. Sorry I can't help with the rest of the gauges... __________________ 70 GMC K2500 82 GMC K3500 09 GMC 2500HD 4x4

03-06-2015, 10:29 AM	#3
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,376	Re: 1972 k20 gauge problems. - Nice truck & to the board. Here is a picture of where the stock gauge cluster ground is attached. The amp gauge never moves much, if at all. There are two 4 amp fuses that are wired into the gauge circuit, one on each side of the core support. Second picture is what they look like. Sometimes the fuses are corroded or broken. Attached Images __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - Last edited by LockDoc; 03-06-2015 at 10:39 AM.

03-06-2015, 10:36 AM	#4
57taskforce All about them K’s Join Date: Jun 2014 Location: Farmington, New Mexico Posts: 6,278	Re: 1972 k20 gauge problems. Sorry I can't be much help with the gauges, but man that's a nice looking truck! __________________ Tyler '57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888 '72 K20 Cheyenne http://67-72chevytrucks.com/vboard/s...d.php?t=662879 ‘69 K10 SWB http://67-72chevytrucks.com/vboard/s...d.php?t=805206 '98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 315/75/16's ‘87 IROC-Z all original 50K mile survivor TPI 305 IROC Blue ‘10 Camaro 2SS/RS Aqua Blue Metallic #93 -version 2.0

03-07-2015, 12:02 AM	#5
low1954 Registered User Join Date: Jun 2014 Location: Washington Posts: 26	Re: 1972 k20 gauge problems. Thanks everyone for all the help, I will cram myself Under the dash this weekend to hopefully find the problem. Thanks again!!

07-12-2015, 12:22 PM	#6
RAMMER Registered User Join Date: May 2015 Location: Devon, UK. Posts: 18	Re: 1972 k20 gauge problems. HI LOCKDOC I am sending you some pictures of the circuit board ,it seems to have a cut on it would this be my problem?. CHEERS RAMMER Attached Images



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