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06-13-2013, 06:21 PM
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#1 |
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Registered User
Join Date: Jun 2013
Location: Lancaster CA
Posts: 15
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Temp Gauge
1970 C-20
I had the instrument panel out and notice the connection plug contacts were dirty; I cleaned them with some steel wool. Didn’t disconnect the battery so got some sparks (I know I’m an idiot). Now has soon as the key is turned on the gauge pegs hot. I have checked the wires for shorts, replaced the sending unit, and replaced the gauge. I hung the gauge outside the panel and ran a new wire from the sender to the gauge and a new wire from gauge to ground, still same result. Any ideas. |
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06-13-2013, 08:05 PM
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#2 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: Temp Gauge
Welcome to the 67-72 Chevy truck forums from West Michigan!
Check the ohm reading from your block unit. Jim
__________________
1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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06-13-2013, 09:01 PM
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#3 |
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Registered User
Join Date: Jun 2013
Location: Lancaster CA
Posts: 15
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Re: Temp Gauge
By block unit do you mean sending unit?
Which I replaced. Tested both but don't know the proper operating range, Do you? |
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06-14-2013, 12:32 AM
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#4 |
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Msgt USAF Ret
  
Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,718
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Re: Temp Gauge
If you want to test the gauge outside the cluster you need to run a ground wire from the gauge body to the truck ground. Then run the the sending unit wire to the left terminal on the gauge as your looking at the back of it and then run a key on hot wire to the right terminal on the gauge. Your gauge should read engine temperature.
If the dark green sending unit wire is grounded somewhere, or the sending unit reads low ohms between the gauge wire terminal and the sending unit body with the wire off the sending unit, then the gauge will read hot. There are two different sending units for the truck clusters. One for the gauge cluster and one for the idiot light cluster. The gauge sender will decrease resistance slowly causing the gauge to read higher temp while the idiot light sending unit will reduce resistance to a low enough value until the light ground is good enough to turn on the light.
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
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06-14-2013, 04:21 PM
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#5 |
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Registered User
Join Date: Jun 2013
Location: Lancaster CA
Posts: 15
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Re: Temp Gauge
Thank you all
The problem seemed to be, when I had the panel apart I painted it and the gauge needs a ground against the shell. All is good now. BIG THANKS TO ALL |
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06-15-2013, 10:26 PM
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#6 |
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Registered User
Join Date: May 2008
Location: Woodlawn, TN
Posts: 275
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Re: Temp Gauge
Funny story, my new guage does exactly that, I thought it was normal. It does read a bit high but I know that 350s tend to run hot as well. Maybe there is something wrong...
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Rocinante: 1972 GMC C25, 292, SM465, 14 bolt, power nothing, 440k and still handles my PCS moves Jorge: Kia Roller-skate with lots of buttons for the wife Wovoka: 2017 Indian Chief Vintage, better on gas but not much So far, this is the oldest I've ever been. |
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