69 Corvette Temperature Gauge
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
69 Corvette Temperature Gauge
Can someone tell me how to trouble shoot the Temperature Gauge and block switch?
It did move when the lead was connected but it bounced to both ends and stopped at the bottom.
I followed the green wire to a temp switch on the block and have yet to trace the other 2 wires as they get lost in the looms.
This is a used OEM gauge that I just bought from the local Corvette shop and it looks great and they said they bench tested it and it works. They are pretty good with me so I would like to trouble shoot the whole system.
Thanks
It did move when the lead was connected but it bounced to both ends and stopped at the bottom.
I followed the green wire to a temp switch on the block and have yet to trace the other 2 wires as they get lost in the looms.
This is a used OEM gauge that I just bought from the local Corvette shop and it looks great and they said they bench tested it and it works. They are pretty good with me so I would like to trouble shoot the whole system.
Thanks
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Are you wanting to test the new gage by itself? Or the unit as a whole.Here is a thread where we talked some of this over.
http://forums.corvetteforum.com/show...ight=temp+gage
http://forums.corvetteforum.com/show...ight=temp+gage
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Are you wanting to test the new gage by itself? Or the unit as a whole.Here is a thread where we talked some of this over.
http://forums.corvetteforum.com/show...ight=temp+gage
http://forums.corvetteforum.com/show...ight=temp+gage
Maybe the other 2 wires are messed up. Should one be power and the other a ground?
Thanks again
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Like other gages, the temp gage is a voltage reading device that is calibrated to your 12 volt system and regulated by the [variable resistance] sensor located on the engine block. You can check the meter by connecting the wiring lugs to a flashlight battery (1.5v AA to 9volt battery). If the meter tries to move to the negative side (CCW), just reverse the leads on the battery. 1.5 volts should just make the meter move up a bit; the 9 volt. battery should peg or nearly peg the meter. DO NOT KEEP THE BATTERY CONNECTED LONG...only long enough to show you that the meter is working. To check out the sending unit, use a volt-ohm-meter (VOM) to measure resistance between the connector terminal and the body of the sensor. If it reads zero ohms or infinite resistance, the sensor is bad [shorted or open]. If you get a measurable reading, the sensor is probably OK. If meter and sensor check good, you probably have a wiring or a grounding problem.
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Like other gages, the temp gage is a voltage reading device that is calibrated to your 12 volt system and regulated by the [variable resistance] sensor located on the engine block. You can check the meter by connecting the wiring lugs to a flashlight battery (1.5v AA to 9volt battery). If the meter tries to move to the negative side (CCW), just reverse the leads on the battery. 1.5 volts should just make the meter move up a bit; the 9 volt. battery should peg or nearly peg the meter. DO NOT KEEP THE BATTERY CONNECTED LONG...only long enough to show you that the meter is working. To check out the sending unit, use a volt-ohm-meter (VOM) to measure resistance between the connector terminal and the body of the sensor. If it reads zero ohms or infinite resistance, the sensor is bad [shorted or open]. If you get a measurable reading, the sensor is probably OK. If meter and sensor check good, you probably have a wiring or a grounding problem.
Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
You need to know if the gage or the temp sender are at fault. To test the gage remove the wire from the temp sender on the block and attach a ground to it. I usually take a test lead with clips and attach it to the alternator bracket and the wire. Then take a look at the gage if it pegs to the right past 250 the gage is functional and it is likely the sender unit doesn't work. If it still doesn't move the gage is toast.
Since the gage is based on resistance the resistence may be compromised by the senders connection to the block. Some people used teflon tape to seal the connection to the block. That worked well but effected the resistance and the gage reads wrong. Clean it all off and try it again. If it is still no good look to replace the sender
Since the gage is based on resistance the resistence may be compromised by the senders connection to the block. Some people used teflon tape to seal the connection to the block. That worked well but effected the resistance and the gage reads wrong. Clean it all off and try it again. If it is still no good look to replace the sender
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Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
You need to know if the gage or the temp sender are at fault. To test the gage remove the wire from the temp sender on the block and attach a ground to it. I usually take a test lead with clips and attach it to the alternator bracket and the wire. Then take a look at the gage if it pegs to the right past 250 the gage is functional and it is likely the sender unit doesn't work. If it still doesn't move the gage is toast.
Since the gage is based on resistance the resistence may be compromised by the senders connection to the block. Some people used teflon tape to seal the connection to the block. That worked well but effected the resistance and the gage reads wrong. Clean it all off and try it again. If it is still no good look to replace the sender
Since the gage is based on resistance the resistence may be compromised by the senders connection to the block. Some people used teflon tape to seal the connection to the block. That worked well but effected the resistance and the gage reads wrong. Clean it all off and try it again. If it is still no good look to replace the sender
Yes, I hope the means the sender is toast, but I will take it out later and test.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
You need to measure the resistance of the sender unit. If it does not measure ZERO ohms or INFINITE ohms, the sender is likely OK. (It should measure something in the 50-100 ohm range, I believe.)
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Melting Slicks
Joined: Oct 2005
Posts: 2,114
Likes: 0
From: upstate N.Y.
If you think it is the sensor get one from lectric limited. I just went through this with new gauge ,sensor .,thermostat and all the tests. The over the counter ones don't work that well. lectric limited solved the problem.
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Does this mean it is toast?
The green wire at the sensor when first grounded pegged the gauge.
I then checked the ohms. Since I thought it was ok I connected everything again and started the car.
The needle jummped past 250 and is now stuck at about where the P is in Water Temp. You got to love this.
My 2 and 4 year old were holding flashlight and helping me so I had to keep my cool, but boy is this getting me.
I know it has to be something simple, cuz they are the things that are the biggest PITA.
I recall someone saying there is a insulated washer on one terminal, I will look when the kids go to bed or after work tomorrow.
Oh crap, my wife invited the in-laws over for me to BBQ for. Maybe Friday night.
Anyways, thats my story, I hope you liked it.
"I need to go fast" Ricky Bobbie
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Yes red in the pic is power,black is ground and green goes to the sender.Make sure that on the black center connector there is a fiber washer under the resistor on the right end.You can do the ground and unground test with the cluster out of the car like this one. If you want to add in the 68ohm test you can be sure the gage is accurate before you put it back in-thats what I do.
Thanks
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
The meter works because the needle moves (pegs); and, in general, if it works, it's OK. You are getting a signal and response, so your wiring is probably OK (unless there is a dead short somewhere). Your sending unit is supplying a signal (not shorted or open), but its low resistance when cold is curious.
I'm leaning toward the calibration resistor on the back side of the meter being damaged or rendered useless by some mechanical short...like if the insulator weren't there or if it was being "defeated" by contact with something else metallic, or damaged during removal or installation.
I'm leaning toward the calibration resistor on the back side of the meter being damaged or rendered useless by some mechanical short...like if the insulator weren't there or if it was being "defeated" by contact with something else metallic, or damaged during removal or installation.
Thread Starter
Racer
Joined: Oct 2006
Posts: 306
Likes: 1
From: Burnaby BC
Ok I have the gauges in my dining room now. 
The needle was not going back to zero when the ground was released.
I noticed that the resistor wire was broken at one end where the washer was rusty and cracked.
I sanded down all the contacts and got new washers and connected a 9v.
With power to 6oclock and ground at 9 if I ground 12oclock it pegs high and return to 100.
I think I got it now.
Will let you know tomorrow.
The needle was not going back to zero when the ground was released.
I noticed that the resistor wire was broken at one end where the washer was rusty and cracked.
I sanded down all the contacts and got new washers and connected a 9v.
With power to 6oclock and ground at 9 if I ground 12oclock it pegs high and return to 100.
I think I got it now.
Will let you know tomorrow.
