Temp & fuel gauge problems - Team Camaro Tech
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post #1 of 18 (permalink) Old Nov 19th, 10, 05:24 PM Thread Starter
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Jason
 
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Temp & fuel gauge problems

Hi, new camaro owner (67 RS/SS 396 4spd) and new to forum. My temp gauge hasn't worked since i've had the car. i replaced the sender, still doesn't work. with ignition on the needle deflects all the way to the left. the fuel gauge initially worked fine but when i took the console mounted gauge set partially out to look at the back and make sure all the wires were hooked up the fuel gauge now deflects way past full when ignition is on... so i'm worse off than when i started. when the temp sending unit wire is grounded there is no change in the situation. Any ideas or help would be much appreciated!
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post #2 of 18 (permalink) Old Nov 19th, 10, 05:46 PM
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Re: Temp & fuel gauge problems

Start by checking your connections, wiring continuity and mainly your grounds. The dash harness is grounded in 2 places, your fuel sender has one located in front of the tank near the tank mount strap and maybe your gauge has one. (OE? Aftermarket?)
Check that those points are good -pref with an Ohms meter.

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #3 of 18 (permalink) Old Nov 19th, 10, 06:05 PM Thread Starter
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Re: Temp & fuel gauge problems

gauges are factory console mount. the only ground i found was a black wire from the console harness to the transmission 'hump' in the floor - that was pretty dirty so i was hopeful that cleaning it up would fix the problem, but no change. where are the grounds supposed to be?
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post #4 of 18 (permalink) Old Nov 19th, 10, 07:02 PM
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Re: Temp & fuel gauge problems

Hmm. I'm looking at UPC 12 of the 67 AIM and I can't see any ground points on the dash harness, not even in the D2 & D3 schematic.
One ground point will be the headlamp switch, but does it ground the entire dash harness? I would also assume the instrument printed circuit board.
Check the left dash support where the park brake mounts and the center dash support for black ground wires..
Sorry. I have a 69.. They're easier!

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #5 of 18 (permalink) Old Nov 20th, 10, 12:45 AM
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Re: Temp & fuel gauge problems

For console gauges, the only ground wire there will be the one you mentioned: from the harness to the transmission tunnel. That wire really just loops around and is the black wire at the back of the gauges. Make sure that all the gauges are getting that ground if they are mounted in separate metal mounts (like the upper and lower gauges in '68-9).

I wonder if you just caused an open at the fuel gauge by disconnecting or losening something without knowing it.?.? Anyway, check that you are getting power to the fuel gauge. The wire to the fuel sendor should show somewhere between 0 and 90 ohms when disconnected from the gauge. Let's hope it's somewhere in the middle (close to half a tank) so that a reading of 0 won't be confusing... If the resistance isn't changing w/ the amount of gas in the tank, then either the wires are bad, sender is bad, or you have a bad ground. If you have voltage and a resistance somewhere in that range, your gauge may be bad.

Grounding the temp sensor wire should change your gauge reading. I forget which way. So, try it w/ the engine cold and hot. If still no change, measure the voltage at the end of the sensor wire. If zero, there is a problem: wire(s) or gauge power. If there is voltage there, maybe you have the wrong sensor?

Just some things to start w/ to use for further diagnosis...


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post #6 of 18 (permalink) Old Nov 20th, 10, 10:00 AM Thread Starter
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Re: Temp & fuel gauge problems

thanks for the help guys! so far i tried grounding the sending terminal on the back of the fuel gauge and it goes to empty as it should, so gauge appears to be working. I unhooked the tan sender wire in the trunk and grounded that and gauge stays on full, so i'm thinking there's an open circuit between the gauge and the sender?? Haven't had a chance to do anything more with the temp gauge yet but will try the things suggested and keep you posted... thanks again!!
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post #7 of 18 (permalink) Old Nov 20th, 10, 01:46 PM
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Re: Temp & fuel gauge problems

Quote:
Originally Posted by D94281 View Post
thanks for the help guys! so far i tried grounding the sending terminal on the back of the fuel gauge and it goes to empty as it should, so gauge appears to be working. I unhooked the tan sender wire in the trunk and grounded that and gauge stays on full, so i'm thinking there's an open circuit between the gauge and the sender??
Don't forget that the fuel gauge's sender also has a ground wire too. Have you check it?
UPC8-B2 shows it's location.

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #8 of 18 (permalink) Old Nov 20th, 10, 02:46 PM Thread Starter
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Re: Temp & fuel gauge problems

OK fuel gauge is now working perfectly! Problem was a loose connector in the plug between the console harness and main harness under dash. now working on temp gauge. there is voltage at the sender wire connection under the hood (10.4V). When I ground the sender terminal on the back of the gauge there is no movement, the gauge stays pegged to the left. From what I've read it should go all the way to hot or right when the sender terminal is grounded. There is voltage at the geen wire terminal(10.8) and at the pink wire terminal on the back of the gauge(10.4). is there something i'm missing or does it seem like the gauge is bad???
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post #9 of 18 (permalink) Old Nov 20th, 10, 03:28 PM
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Re: Temp & fuel gauge problems

Is there a resistor on the back of your temp gauge? You may want to take some measurements of it first. Could be burned up... Since there is voltage to and from the gauge, it does point towards gauge issue(s). Are the terminals and connector arranged like they are in the console diagrams (AIM?, RS & console wiring diagrams)?


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post #10 of 18 (permalink) Old Nov 21st, 10, 08:48 AM Thread Starter
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Re: Temp & fuel gauge problems

Quote:
Originally Posted by flyingskibiker View Post
Is there a resistor on the back of your temp gauge? You may want to take some measurements of it first. Could be burned up... Since there is voltage to and from the gauge, it does point towards gauge issue(s). Are the terminals and connector arranged like they are in the console diagrams (AIM?, RS & console wiring diagrams)?
terminals and connectors seem to be arranged per AIM diagram. any idea what the resistance through the gauge should be?
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post #11 of 18 (permalink) Old Nov 21st, 10, 07:12 PM Thread Starter
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Re: Temp & fuel gauge problems

ok, i took the resistor off the back of the temp gauge and checked the resistance across it and it is about 80 ohms. not sure what it is supposed to be but at least i know its not 'open'. interestingly when i put it back together i looked at the AIM diagram and i think the pink and green leads may have been reversed when i took it apart but i'm not for sure. either way it's hooked up correctly now and is no longer pegged at 9 o'clock. it reads slightly above cold and when i ground the sender terminal now it moves about an eight of an inch towards hot which is the first time it's at least moved in the right direction! Since it doesn't go all the way to hot does this mean the gauge is toast or is there sonething else i can try? thanks again for the helpful replies - i feel like i'm getting somewhere...
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post #12 of 18 (permalink) Old Nov 21st, 10, 09:45 PM
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Re: Temp & fuel gauge problems

Is the resistance you measured across the resistor off the gauge or the gauge w/o the resistor? I'm pretty sure the gauge should also have it's own resistance. The reading of the gauge would then just be a voltage (divider) reading w/ a temperature scale on it...

Check replies 40 and 41 in this thread for a picture of the back of the gauges and some resistance measurments:
https://www.camaros.net/forums/showth...=177673&page=3

You know what, I think that the wires are backwards on his picture... Let me go get my gauges.

Yup. Looking at the picture, the Pink wire should connect to the terminal on the right, the green on the left.


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post #13 of 18 (permalink) Old Nov 22nd, 10, 04:01 PM Thread Starter
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Re: Temp & fuel gauge problems

resistance measured was across the resistor off of the gauge. Any way to test the gauge itself other thab groynding the sender wire. Doing this produces a little movement in the right direction but doesn't peg the gauge to the hot side like it's supposed too,
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post #14 of 18 (permalink) Old Nov 26th, 10, 09:40 PM Thread Starter
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Jason
 
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Re: Temp & fuel gauge problems

thanks to all for the help. both temp and fuel gauge are now fully operational! Turns out the sender was bad - open circuit when resistance measured across the unit. Also the gauge was bad - would only deflect minor amounts even when grounded or opened. Replace both and now works. I also took the clock apart and got it to work if anyone is interested in those details... thanks again!
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post #15 of 18 (permalink) Old Nov 26th, 10, 11:50 PM
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Re: Temp & fuel gauge problems

Well done Jason.

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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