Temp Gauge Tech Help
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From: Waynesboro, Virginia
Temp Gauge Tech Help
I'm trying to figure why a (Stewart-Warnet) temp gauge isn't working.
I reads nothing at any time.
I don't know if it's a sender or the gauge itself. There is power to the gauge...I hooked my multi-meter up to the sender wire disconnected at the sender and the numbers change when the key is on. This seems to indicate to me that the gauge is probably working properly. I didn't apply any voltage to the gauge directly; wasn't sure if it would ruin the gauge.
The sending unit, when connected from input to ground gives me no reading whether cold or not. The unit is grounded....it used to work (it is about 25 years old though), and I checked the ground from sender housing to battery ground. Since I get nothing as a reading on the sending unit, my first thought is that it is not functioning.
My question is: Shouldn't I get a reading on the sending unit when metered from input to ground? I don't have one in the box to check, put in hot water, etc. I can get one, but I thought I'd just ask first.
Thanks,
Paul
I reads nothing at any time.
I don't know if it's a sender or the gauge itself. There is power to the gauge...I hooked my multi-meter up to the sender wire disconnected at the sender and the numbers change when the key is on. This seems to indicate to me that the gauge is probably working properly. I didn't apply any voltage to the gauge directly; wasn't sure if it would ruin the gauge.
The sending unit, when connected from input to ground gives me no reading whether cold or not. The unit is grounded....it used to work (it is about 25 years old though), and I checked the ground from sender housing to battery ground. Since I get nothing as a reading on the sending unit, my first thought is that it is not functioning.
My question is: Shouldn't I get a reading on the sending unit when metered from input to ground? I don't have one in the box to check, put in hot water, etc. I can get one, but I thought I'd just ask first.
Thanks,
Paul
Last edited by theGman; Jul 16, 2007 at 07:34 PM.
Logistics Pro
Joined: Dec 2005
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From: Moro Bay, AR
The wire for the sender is in the ground circuit of the gauge, so if you ground the wire, the gauge should read all the way to hot. If this works, replace the sender, if not, check wiring to gauge.
Postmaster
Joined: Apr 2004
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From: Santa Clarita
This is a reason I use mechanical gauges! Randy, I use teflon tape on my sending units all the time and have never had a problem? I guess if you tape over the temp sensor on the sending unit, that would effect it?
Roast em' if you got 'em
Joined: Mar 2005
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From: Rio Rancho, NM
The teflon tape can insulate the sender from the engine block creating an open circuit. Since the body of the sender is part of the circuit it needs good continuity between it and the engine block(ground)
(on my big Caddy engine the temp sender is not easy to get to, you can barely get a wrench near it. Well, when the engine was still on the engine stand I was happily sipping a frosty beverage and putting things together I installed teh temp and oil senders with teflon tape. After the engine was in the truck and the cooling system was filled and I was finishing the wiring it hit me that I had used teflon tape on both the coolant temp and oil pressure sending units....AAAGH! I had to change them both out.)
Even when you know better you can still mess it all up.........lol
Bobby
(on my big Caddy engine the temp sender is not easy to get to, you can barely get a wrench near it. Well, when the engine was still on the engine stand I was happily sipping a frosty beverage and putting things together I installed teh temp and oil senders with teflon tape. After the engine was in the truck and the cooling system was filled and I was finishing the wiring it hit me that I had used teflon tape on both the coolant temp and oil pressure sending units....AAAGH! I had to change them both out.)
Even when you know better you can still mess it all up.........lol
Bobby
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Joined: Sep 2004
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From: Appleton, Wisconsin
Related topic: I installed a mechanical water temp gauge on the drivers side. I took the 2 wires that came into the original sender drivers side (electric gauge) and connected them, so the passenger side original sender is connected to the dash gauge.
I drove the truck to work, 20 minute drive in the burbs, and the mech gauge read 170 (180 stats in), the original electric guage stayed at the "H" all the way there. It started out reading at 1/4 but shot up rapidly.
This gauge was running what I considered hot before I put in the mech gauge. it was 3/4 hot and crept up a bit more at 55mph driving making me very nervous. Now with just one sender connected it runs hotter yet on the needle.
Does it sound like the gauge is going, or the sender? Maybe the cvr?
I drove the truck to work, 20 minute drive in the burbs, and the mech gauge read 170 (180 stats in), the original electric guage stayed at the "H" all the way there. It started out reading at 1/4 but shot up rapidly.
This gauge was running what I considered hot before I put in the mech gauge. it was 3/4 hot and crept up a bit more at 55mph driving making me very nervous. Now with just one sender connected it runs hotter yet on the needle.
Does it sound like the gauge is going, or the sender? Maybe the cvr?
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From: Waynesboro, Virginia
No, I didn't install it with Teflon tape; I didn't install it period. It was working a year ago, plus, as I mentioned, I checked the ground from the sender to negative terminal and was fine, so the unit is grounded.
Related: I have used teflon tape "by accident" on electrical sending units and for some reason never had a grounding or a gauge reading problem. Somehow they always are grounded even with the tape.
Related: I have used teflon tape "by accident" on electrical sending units and for some reason never had a grounding or a gauge reading problem. Somehow they always are grounded even with the tape.
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Joined: Feb 2007
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If you put an Ohm meter between the sending unit output and the body of the unit (ground) you should get a reading if it is working properly. Put it in hot water and that reading should change either up or down depending on the type of sender it is. Almost all senders work by varying the resistance based on what they are sensing (water temp, oil pressure, fuel level, etc.) Therefore an Ohm meter is pretty much required for diagnosing guage and sender problems. You can get a very servicable meter a Radio Shack for around $25 or less.
Good luck
Good luck
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From: NM
Originally Posted by snipa
Related topic: I installed a mechanical water temp gauge on the drivers side. I took the 2 wires that came into the original sender drivers side (electric gauge) and connected them, so the passenger side original sender is connected to the dash gauge.
I drove the truck to work, 20 minute drive in the burbs, and the mech gauge read 170 (180 stats in), the original electric guage stayed at the "H" all the way there. It started out reading at 1/4 but shot up rapidly.
This gauge was running what I considered hot before I put in the mech gauge. it was 3/4 hot and crept up a bit more at 55mph driving making me very nervous. Now with just one sender connected it runs hotter yet on the needle.
Does it sound like the gauge is going, or the sender? Maybe the cvr?
I drove the truck to work, 20 minute drive in the burbs, and the mech gauge read 170 (180 stats in), the original electric guage stayed at the "H" all the way there. It started out reading at 1/4 but shot up rapidly.
This gauge was running what I considered hot before I put in the mech gauge. it was 3/4 hot and crept up a bit more at 55mph driving making me very nervous. Now with just one sender connected it runs hotter yet on the needle.
Does it sound like the gauge is going, or the sender? Maybe the cvr?