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09-11-2018, 10:18 AM
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#1 |
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Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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Temp idiot light ?
My temp dash light works perfect when I ground the wire on the block but doesn't work when on sensor?
I bought a new sensor but no luck. Would using plumbers tape block the ground?
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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09-11-2018, 10:56 AM
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#2 |
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Registered User
Join Date: Jul 2012
Location: Space Coast, Florida
Posts: 403
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Re: Temp idiot light ?
How would you know unless the engine over heats? Is it getting hot enough to trip the temp light?
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1968 SWB Step Side, Big Block, 4L80E , Running! |
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09-11-2018, 10:58 AM
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#3 |
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Who Changed This?
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,081
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Re: Temp idiot light ?
I'm guessing that when you turn the key to the "start" position, the temp light doesn't light? I never use Teflon tape on sensors that work by grounding. Though I think that there is a circuit on the "start" side that only tests that the light itself works.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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09-11-2018, 11:07 AM
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#4 | |
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Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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Re: Temp idiot light ?
Quote:
I am thinking bad sensor, wrong sensor sent, or the plumbers tape....but not sure with electrical
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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09-12-2018, 02:18 PM
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#5 |
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Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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Re: Temp idiot light ?
Anybody?
I'll take the dope off and see if that is it.
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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09-12-2018, 05:21 PM
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#6 | |
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The Older Generation
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,319
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Re: Temp idiot light ?
Quote:
LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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09-12-2018, 06:03 PM
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#7 |
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Senior Member
Join Date: Jan 2016
Location: Sugar Hill GA
Posts: 368
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Re: Temp idiot light ?
I will use thread sealer on sensors but NEVER tape. Never had an issue with thread sealer.
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1967 C10 Step side 1970 AMX 390 1977 Datsun 280Z highly modified with '95 LT1 power |
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09-12-2018, 06:52 PM
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#8 |
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laying low
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 12,947
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Re: Temp idiot light ?
The temp light uses a different sensor than the temp gauge if you didn't know.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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09-12-2018, 06:57 PM
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#9 |
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Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Temp idiot light ?
I've never had it happen but I've read not to use the tape for that very reason...
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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09-12-2018, 07:42 PM
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#10 |
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Junior Member
Join Date: Oct 2015
Location: FRG, IL
Posts: 29
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Re: Temp idiot light ?
Tape will cause it not to ground to the block, remove the tape and it should be okay.
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71 C/10 "Brooke" - The Rat Rod Tow Truck 98 Blazer "Hulky" - The Tow Rig - Sold 11 Regal - The DD 76 Kawasaki KZ900 - One Day I'll fix it 06 Street Bob - Soon to be Sold |
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09-12-2018, 10:08 PM
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#11 |
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Registered User
Join Date: Mar 2014
Location: Lincoln Park, NJ
Posts: 189
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Re: Temp idiot light ?
If the problem is that the temp light (and/or brake light) doesn't light when cranking, the problem is between the light and the ignition switch.
The ignition switch provides a separate ground for the two lights when the key is in the cranking position.
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 1970 C10 LWB 350SBC, SM330 Muncie (not saginaw SM326) (on tree), 3.07 open (assumed), PS, PB, Idiot lights
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09-20-2018, 11:00 AM
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#12 |
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Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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Re: Temp idiot light ?
I took the tape off and no workee
The sensor is brand new from lmc Maybe they sent the wrong one. Or a dud The brake light lights up great and the temp does too when I ground the wire on the block bypassing the sensor... Let's try lmc customer service out. See if they will send another one.....
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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09-20-2018, 11:38 AM
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#13 |
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Registered User
Join Date: Feb 2011
Location: Parkville, MD
Posts: 1,024
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Re: Temp idiot light ?
Coming from more of an electrical background and not experience with the idiot light on these trucks.
The sensor has 1 wire going to it correct? How would it know if you are on / off / cranking? Assuming the circuit is ground - sensor - sensor wire - light - ignition, I don't see how the light can test the sensor. The only way you can test the sensor, it to get it hot enough for the switch to close. I don't know what that threshold is. Might be able to test it by boiling water or coolant. Drop the sensor in and looking for continuity.
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1970 C20 Custom Camper - 350, TH350 1997 GMC Suburban 1994 Acura Integra GSR 1987 Dodge Daytona Shelby Z |
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09-20-2018, 11:45 AM
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#14 |
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Registered User
Join Date: Feb 2011
Location: Parkville, MD
Posts: 1,024
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Re: Temp idiot light ?
http://outintheshop.com/faq/wiring/w...s/image002.jpg
http://outintheshop.com/faq/wiring/w...s/image003.jpg Going off of what zosoppp said. The ground in the ignition switch. You can see both the temp light and brake light go through the ignition switch in the second schematic. This would be how they test the light. It's the 20 DG wire.
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1970 C20 Custom Camper - 350, TH350 1997 GMC Suburban 1994 Acura Integra GSR 1987 Dodge Daytona Shelby Z |
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09-20-2018, 01:03 PM
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#15 |
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Msgt USAF Ret
 
Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,703
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Re: Temp idiot light ?
The key switch grounds the temp and brake light circuits when it is turned to start to check the bulbs.
Here is a picture of one with the brown and green wires connected. The wires run from the sensors to the key switch then to the dash cluster plug. Here is a picture of the plug wiring for the light dash. Here is a diagram of the wiring from the key switch (top) to the cluster (middle) Here is a diagram of the cluster showing the brake warning wire (20 tan ) to terminal 2, and the temperature gauge wire ( 20 dark green) to terminal 5. Here is a better picture of the wiring diagram. Ignore the blue arrow, that is the headlight switch.
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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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09-20-2018, 04:17 PM
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#16 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,081
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Re: Temp idiot light ?
^^^^ Yup. It's what I meant in post #3, but I didn't try to dig up the diagram, cuz I know VetteVet has the definitive answer. I didn't want to possibly muddy the water, and his answer is dead clear.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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09-28-2018, 10:06 AM
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#17 |
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Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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Re: Temp idiot light ?
Wow thanks .
Like a surgeon Went through all my invoices and it was from rockauto. Wrong sensor sent for 100 Bob.
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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