![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
![]() |
#1 |
Registered User
Join Date: Mar 2017
Location: B-Spa, NY
Posts: 8
|
Temperature gauge pegged??
Ok, I need help...
72 C20. Truck had a motor swap some time ago, never had the temp gauge hooked up. Bought a new sending unit, and was planning to install it, but noticed my gauge is pegged right/hot all the time. Regardless whether the key is turned on or not. Read through the forum threads, saw the diagrams, common issues , can't seem to figure out why it's pegged all the time. Found this handy diagram on here... -Seeing 12V on the post at 3 o'clock. -Seeing same 12v on the post at 9 o'clock. Going off to sending unit. -Found dark green cable leaving bulkhead, followed it.. it's disconnected in engine-bay. Seeing the same 12V on the disconnected end. -Ran continuity test from green-cable (engine-bay) to gauge post at 9 oclock... looks good. I would expect since the sending unit is disconnected in engine bay, the gauge would read 'low/left'? Not pegged high? I tried to jump ground on post at 6 o'clock to ground...nothing, still pegged. Now, granted my sending unit is still disconnected, but shouldn't I see that needle move a little left at some point? Oh, also pulled back circuit board from posts at 3 and 9 oclock.. no change. Bad gauge? Is my logic flawed? Do I just install sending unit, and keep my fingers crossed??? Help!!! |
![]() |
![]() |
![]() |
#2 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
|
Re: Temperature gauge pegged??
Sounds like a dead short
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Oct 2016
Location: Seneca, KS
Posts: 12
|
Re: Temperature gauge pegged??
If the green wire is shorted to ground, it will read full-hot. If you remove the green wire from the gauge, the needle should drop to cold. If it doesn't, you have a gauge problem. From your note about 12V on green wire in the engine bay, I suspect gauge problem.
|
![]() |
![]() |
![]() |
#4 |
Registered User
Join Date: Mar 2017
Location: B-Spa, NY
Posts: 8
|
Re: Temperature gauge pegged??
Thanks for the replies.
By pulling back the printed circuit board, I'm essentially disconnecting the green wire from the gauge. When I do that, it's still pegged. I'll probably just replace the gauge. Time to start researching that process. |
![]() |
![]() |
![]() |
Bookmarks |
|
|