Pull on the lights = temp gauge peg!!
Thread Starter
Instructor
Joined: Apr 2005
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Pull on the lights = temp gauge peg!!
I've been messing with a new to me '81 and have not driven it much at all, no night driving what so ever. I just replaced the oil temp sensor, oil pressure gauge and printed board for the cluster. Fired her up and everything bounced and looked like it should for a cold engine. For some reason I pulled the headlights on and wham, the coolant temp pegs and I get a warning buzzer, what's up with that, a warning buzzer??? Turn the lights off, back to normal. Drove it back in the shop for the evening and I'll think about it a little, plus ask you guys. I'm thinking ground????? How about you? Thanks
Drifting
Joined: Aug 2009
Posts: 1,635
Likes: 8
From: Enid Oklahoma
I've been messing with a new to me '81 and have not driven it much at all, no night driving what so ever. I just replaced the oil temp sensor, oil pressure gauge and printed board for the cluster. Fired her up and everything bounced and looked like it should for a cold engine. For some reason I pulled the headlights on and wham, the coolant temp pegs and I get a warning buzzer, what's up with that, a warning buzzer??? Turn the lights off, back to normal. Drove it back in the shop for the evening and I'll think about it a little, plus ask you guys. I'm thinking ground????? How about you? Thanks
Safety Car
Joined: Aug 2001
Posts: 3,683
Likes: 202
From: Waterford Mi
Sounds like a bad ground to the gages. I had this with my 73, (no circut board), after a PO replaced the radio and did not hook the ground wire up. I discovered the isse when I was replacing the bulbs. Everytime I turned on the lights my temp gage would jump 30-40 degrees.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Grounds do cause serious and weird issues with gauges. You said the gauge "pegs" , I'm going to assume it pegs to full.
What makes the temp gauge peg to full ?
If the sender wire is grounded it will send the needle to hot.
Chances are that is not the problem.
I don't have notes on different scenarios but (hopefully Ernie will chime in) but I believe if the gauge has power and the sender wire is attached to a good sender and the ground from the gauge disappears the needle goes to hot. If you go to the Willcox site Ernie has all the scenarios listed in his help section.
Being that you just installed the new printed circuit (and the large plug in connector is probably not the problem) I would have to guess you have not installed the fiber washer combination's correctly.
Recheck the printed circuit, I think the gauges at present are grounding through the dash inst. bulbs until you turn on the headlights and the ground goes away.
Just for fun pop out the 7.5 INST lamp fuse and see if that temp fixes the problem and the buzzer.
What makes the temp gauge peg to full ?
If the sender wire is grounded it will send the needle to hot.
Chances are that is not the problem.
I don't have notes on different scenarios but (hopefully Ernie will chime in) but I believe if the gauge has power and the sender wire is attached to a good sender and the ground from the gauge disappears the needle goes to hot. If you go to the Willcox site Ernie has all the scenarios listed in his help section.
Being that you just installed the new printed circuit (and the large plug in connector is probably not the problem) I would have to guess you have not installed the fiber washer combination's correctly.
Recheck the printed circuit, I think the gauges at present are grounding through the dash inst. bulbs until you turn on the headlights and the ground goes away.
Just for fun pop out the 7.5 INST lamp fuse and see if that temp fixes the problem and the buzzer.
Thread Starter
Instructor
Joined: Apr 2005
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Roger, I was able to get back on the vett today. First thing I did was start it with nothing done since last time. Before going to crank the water temp gauge "full scaled" just like before. About 20 seconds after starting, the gauge went back to normal, cold. While letting it run I messed with the headlight switch, as in rotated to turn up the dimmed lights and low and behold I could control how warm the engine was 
. The buzzing that I had before was the seat belt reminder but it wouldn't turn off then or now unless I plugged the seat belt into it's other end.
Next was your idea, I turned the car off and had my leprechaun climb up under the dash and pull that 7.5 fuse you mentioned. Waited for him to get back down and turned the key to run. The guage didn't full scale. Turned to start and she lit and the gauge didn't do any wild dances, just what it should do with a cold engine, sat there. I tuned the **** and nothing happened, I couldn't get the engine to get warm let alone hot like before with the fuse in and the seatbelt buzzer went off just as it should in about 10 seconds.
So, now we have what appears to be a normal cluster/buzzer without lights.
My next move?????????? Thanks
. The buzzing that I had before was the seat belt reminder but it wouldn't turn off then or now unless I plugged the seat belt into it's other end.Next was your idea, I turned the car off and had my leprechaun climb up under the dash and pull that 7.5 fuse you mentioned. Waited for him to get back down and turned the key to run. The guage didn't full scale. Turned to start and she lit and the gauge didn't do any wild dances, just what it should do with a cold engine, sat there. I tuned the **** and nothing happened, I couldn't get the engine to get warm let alone hot like before with the fuse in and the seatbelt buzzer went off just as it should in about 10 seconds.
So, now we have what appears to be a normal cluster/buzzer without lights.
My next move?????????? Thanks
Last edited by boatdoc; Apr 14, 2010 at 12:16 AM.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I "think" your gauge is grounding through the dash light circuit and when you turn the dash lights on the ground disappears.
Again without seeing it I'm guessing the temp gauge doesn't have the factory ground. Probably has to do with the installation of the new printed circuit, go back and check the fiber washers ,I think you have a washer where there shouldn't be one or the grounding for the gauge at the large connector isn't making contact.
http://willcoxcorvette.com/instructi...ions_68-82.jpg
Again without seeing it I'm guessing the temp gauge doesn't have the factory ground. Probably has to do with the installation of the new printed circuit, go back and check the fiber washers ,I think you have a washer where there shouldn't be one or the grounding for the gauge at the large connector isn't making contact.
http://willcoxcorvette.com/instructi...ions_68-82.jpg
Thread Starter
Instructor
Joined: Apr 2005
Posts: 126
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Fixed!!!!!
Thanks for all the help and thought I'd be a good boy and report back with what I found with the center cluster. I think I'm getting older and things are starting to slip a little after 41 years of turning wrenches. I didn't tighten up three rear nuts on one of the gauges and the ribbon wasn't making good contact. YEEZ 
Hard to admit it but that's what it was. Oh well I needed some practice on pulling the seats, tunnel covers, defogger switch and cluster anyway.
Thanks again
Hard to admit it but that's what it was. Oh well I needed some practice on pulling the seats, tunnel covers, defogger switch and cluster anyway.Thanks again
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