Engine Temp Warning Light? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72SB · 01-25-2023, 04:23 PM

72 C10 with the gauge package option 253, amp, oil temp gauge.

The dash light for this "Engine Temp Warning" does not work when KOEO or while cranking the motor over. I have 2 senders. One on T stat housing base with a green/white stripe wire to it and a sender on the head (6 cyl) that has what appears to be a dark green (possibly black) wire to it and is a heavier gauge wire than the one to the other sender

Which one of these senders is associated with the Engine Temp Warning light?

I did pull that bulb and with bulb in its socket continuity test fail, Blub test good. Scraped brass insert that bulb slides in and now have continuity with bulb inserted in socket.

Temp Gauge works.

Both senders appear to be original but the wire on T stat base appears newer so may have been spliced or replaced at some point in its life. I have not un-taped that loom to see if that wire color, green with white stripe, is continues or is spliced into another color, original, wire.

or is the Engine Temp Warning light with the gauge option nonfunctional?

**pjmoreland** · 01-25-2023, 07:00 PM

The engine temp light with the gauge option is not functional. It is not wired.

ray_mcavoy · 01-25-2023, 11:28 PM

Yes, temp light is non functional / not wired with the full gauge cluster. I believe the only reason it's even present is because it's part of the gas gauge assembly ... which is the same as used in warning light clusters.

As for the engine having 2 temp sending units, I think one of them may be a temp switch for TCS (Transmission Controlled Spark) ... an early emissions system that GM used on many early 70's vehicles.

72SB · 01-26-2023, 11:26 AM

Quote:

Originally Posted by ray_mcavoy

As for the engine having 2 temp sending units, I think one of them may be a temp switch for TCS (Transmission Controlled Spark) ... an early emissions system that GM used on many early 70's vehicles.

It's a 3 OTT....

these pics show the sensor locations

One on head, DS and the other just under the T stat housing

**jaros44sr** · 01-26-2023, 08:51 PM

Dang that's a Purdy engine bay

Wish mine looked like that

**70STOVEBOLT** · 01-26-2023, 09:26 PM

The 3 OTT trucks had TCS also. Mine did, but I don’t remember what color the wire was. I don’t see a TCS solenoid on your firewall by the heater box.

01-25-2023, 04:23 PM	#1
72SB Registered User Join Date: Apr 2022 Location: Moorpark, CA Posts: 775	Engine Temp Warning Light? 72 C10 with the gauge package option 253, amp, oil temp gauge. The dash light for this "Engine Temp Warning" does not work when KOEO or while cranking the motor over. I have 2 senders. One on T stat housing base with a green/white stripe wire to it and a sender on the head (6 cyl) that has what appears to be a dark green (possibly black) wire to it and is a heavier gauge wire than the one to the other sender Which one of these senders is associated with the Engine Temp Warning light? I did pull that bulb and with bulb in its socket continuity test fail, Blub test good. Scraped brass insert that bulb slides in and now have continuity with bulb inserted in socket. Temp Gauge works. Both senders appear to be original but the wire on T stat base appears newer so may have been spliced or replaced at some point in its life. I have not un-taped that loom to see if that wire color, green with white stripe, is continues or is spliced into another color, original, wire. or is the Engine Temp Warning light with the gauge option nonfunctional?

01-25-2023, 07:00 PM	#2
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 6,066	Re: Engine Temp Warning Light? The engine temp light with the gauge option is not functional. It is not wired.

01-25-2023, 11:28 PM	#3
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,367	Re: Engine Temp Warning Light? Yes, temp light is non functional / not wired with the full gauge cluster. I believe the only reason it's even present is because it's part of the gas gauge assembly ... which is the same as used in warning light clusters. As for the engine having 2 temp sending units, I think one of them may be a temp switch for TCS (Transmission Controlled Spark) ... an early emissions system that GM used on many early 70's vehicles.

01-26-2023, 08:51 PM	#5
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,779	Re: Engine Temp Warning Light? Dang that's a Purdy engine bay Wish mine looked like that __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

01-26-2023, 09:26 PM	#6
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,467	Re: Engine Temp Warning Light? The 3 OTT trucks had TCS also. Mine did, but I don’t remember what color the wire was. I don’t see a TCS solenoid on your firewall by the heater box. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear



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