Water Temperature Gauge Fix?
Thread Starter
Instructor
Joined: Feb 2017
Posts: 209
Likes: 21
From: Iowa
Water Temperature Gauge Fix?
What is the easiest thing to check first? Should I look at the CTS on the engine, or mess with the gauge? The car is a 1982. The only real electrical tool I have is a multimeter, so hopefully it will do the trick. Does the gauge changed based on resistance? If I can recall, the needle "parks" itself when the engine is started, but doesn't move after that. Thanks for all the help!
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
What is the temp gauge doing? Yes it works on resistance but it's no linear...
There is a ton of info on my site about your temperature gauge. http://repairs.willcoxcorvette.com/?yt=1982&s=temp
Post back what the gauge is doing.. it'll tell you what is wrong with it.
Testing a 68-82 Temperature Gauge -or- What your non working gauge can tell you! I know the title says 68-76 but the 77-82 will tell you the same thing only with a different face.
There is a ton of info on my site about your temperature gauge. http://repairs.willcoxcorvette.com/?yt=1982&s=temp
Post back what the gauge is doing.. it'll tell you what is wrong with it.
Testing a 68-82 Temperature Gauge -or- What your non working gauge can tell you! I know the title says 68-76 but the 77-82 will tell you the same thing only with a different face.
Thread Starter
Instructor
Joined: Feb 2017
Posts: 209
Likes: 21
From: Iowa
I've been to your site but have never noticed all the tech articles. You've got some amazingly helpful info there!
Based on what I have read so far, I either have a bad sending unit, bad thermostat, or some faulty wiring in between because it will move to the cold position with the engine running/ignition on. Should I short circuit the signal with the ground on the back of the gauge?
My CTS looks different than the one listed for the '82 on your website - it's got a round connector. I have read about people doing conversions, but I guess I should rule out other issues before messing with that right away.
Based on what I have read so far, I either have a bad sending unit, bad thermostat, or some faulty wiring in between because it will move to the cold position with the engine running/ignition on. Should I short circuit the signal with the ground on the back of the gauge?
My CTS looks different than the one listed for the '82 on your website - it's got a round connector. I have read about people doing conversions, but I guess I should rule out other issues before messing with that right away.
What is the temp gauge doing? Yes it works on resistance but it's no linear...
There is a ton of info on my site about your temperature gauge. http://repairs.willcoxcorvette.com/?yt=1982&s=temp
Post back what the gauge is doing.. it'll tell you what is wrong with it.
Testing a 68-82 Temperature Gauge -or- What your non working gauge can tell you! I know the title says 68-76 but the 77-82 will tell you the same thing only with a different face.
There is a ton of info on my site about your temperature gauge. http://repairs.willcoxcorvette.com/?yt=1982&s=temp
Post back what the gauge is doing.. it'll tell you what is wrong with it.
Testing a 68-82 Temperature Gauge -or- What your non working gauge can tell you! I know the title says 68-76 but the 77-82 will tell you the same thing only with a different face.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The actual gauge sender that works the temperature gauge in the dash should have a dark green wire running off of it. You can verify this by grounding this wire with the key on and see what the gauge does.. it should peg cold.
From the looks of your pcb, either someone has converted this car to an oil temperature sending cluster or someone replaced the pcb. You can tell this by the fact that there is electrical tape over the end of the pcb where the oil temp gauge is located. Original cars with an oil temp gauge didn't have that finger in the pcb, it was for powering up the clock that would have been in that position. The pcb on your cluster does however look to be original.
But even the oil temp sender was a one wire sender... the power and ground for that gauge came from the main harness on a separate connector.
This picture is not an original PCB but rather from one of our Gerber file we are working on to produce this part in the future.
From the looks of your pcb, either someone has converted this car to an oil temperature sending cluster or someone replaced the pcb. You can tell this by the fact that there is electrical tape over the end of the pcb where the oil temp gauge is located. Original cars with an oil temp gauge didn't have that finger in the pcb, it was for powering up the clock that would have been in that position. The pcb on your cluster does however look to be original.
But even the oil temp sender was a one wire sender... the power and ground for that gauge came from the main harness on a separate connector.
This picture is not an original PCB but rather from one of our Gerber file we are working on to produce this part in the future.
Thread Starter
Instructor
Joined: Feb 2017
Posts: 209
Likes: 21
From: Iowa
I've got an update! With the engine running/ignition on, I both the oil temperature and water temperature gauges move to their minimum readings. When I ground the sender connection for either gauge, they max out. I'm thinking this means the gauges are good. What should my next troubleshooting steps be?
I've attached a photo of my CTS, and the PCB, after I mistakingly touched the wrong two terminals together. I'll probably have to buy a new PCB, but my quick fix was enough for this test. Stupid me, but I suppose mistakes are bound to happen when working on an old car!
I've attached a photo of my CTS, and the PCB, after I mistakingly touched the wrong two terminals together. I'll probably have to buy a new PCB, but my quick fix was enough for this test. Stupid me, but I suppose mistakes are bound to happen when working on an old car!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If you pulled the wires off the senders and did the "open" and "shorted to ground" tests with normal results, then the sending units are defective.
P.S. The electrical ground path for those gauges flows through the sending unit bodies to the engine block (or cylinder head). If you have Teflon tape on the sender fitting threads, the sender may not be making a good ground connection.
P.S. The electrical ground path for those gauges flows through the sending unit bodies to the engine block (or cylinder head). If you have Teflon tape on the sender fitting threads, the sender may not be making a good ground connection.
7th Gear
Joined: Dec 2011
Posts: 7
Likes: 0
From: Regina Saskatchewan
Hi all, with my water temp gauge wire connected when I turn the key the gauge actually moves lower to the left and stays there. If I take it off from the sending unit and try ground it it doesn't move... coincidentally my alternator is charging however the light is staying on as well.... and if I disconnect my negative battery post and run a multimeter from the ground wire to post is shows 12.4 volts... yes my battery drains if I leave it connected... sorry, don't mean to hijack the post.. think it might all be connected? All was working fine until I was dead at the side of the road one day and they replaced my electronic ignition module... 78 383 stroker
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