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73-87 Chevy _ GMC Trucks => Interior & Equipment => Topic started by: Todd7080 on March 29, 2011, 11:12:35 PM

Title: Fule gauge falls past empty when I turn on the head lights.
Post by: Todd7080 on March 29, 2011, 11:12:35 PM

 Hi everyone Im new to this site as far as being a member but have used info from here for years. I just put a better looking set of gauges in my original housing and when the key is turned on the needle went to the correct spot. With the key off I turned the headlights on and the fuel needle fell to the left way past the E. if I turn the key on it goes to the correct spot again. i didn't have this problem before I started and that frustrates me. The printed circuit in only 4 years old also. Any help would be much appreciated.
 Thanks...

Title: Re: Fule gauge falls past empty when I turn on the head lights.
Post by: 1979C20 on March 29, 2011, 11:50:07 PM

Why would you turn your headlights on without the key on or the truck running? And, it sounds like maybe a ground problem. My gas gauge hardly moved at all and it would run out of gas on my when it was still over 1/4 tank. But I found the ground wire from the back side if the passenger.head into the fire wall was iff and I hooked it up and now it works how it should and E is actually empty. Check your gauge ground wire and make sure you have everything hooked up right.

Title: Re: Fule gauge falls past empty when I turn on the head lights.
Post by: beastie_3 on March 30, 2011, 01:31:08 PM

if the fuel gauge is correct with truck ON and lights ON, then I wouldnt worry about it.

Title: Re: Fule gauge falls past empty when I turn on the head lights.
Post by: bake74 on April 01, 2011, 09:40:09 PM

     1979c20 is on the right track, has to be a wire issue.  If it was me I would go to the tech section here and get the wiring diagrams for your truck, then trace the fuel circuit and headlight circuit ( you might want to try to see if other switches do it also ), it really sounds like to me that somehow you grounded/crossed the two circuits,and with out the truck running you turn on the headlights and "drain" the power from the fuel gauge circuit.  Electrical issues can be a nightmare and a headache, but if you approach it with a plan and remember to take the simple steps first you should be able to trace the problem. 
     Good luck and keep up informed, welcome to the site also from California.

Title: Re: Fule gauge falls past empty when I turn on the head lights.
Post by: Todd7080 on April 04, 2011, 10:43:10 PM

Thanks everyone for the input. I will take the dash back apart and find the issue soon. I can't stand things not working like they are supposed to. What boggles my mind is the gauge I took out worked like a champ. I just replaced it because it didn't match the rest of them.

Title: Re: Fule gauge falls past empty when I turn on the head lights.
Post by: beastie_3 on April 04, 2011, 11:16:13 PM

If all you did was replace the gauge, then it could just be the new gauge...Put the old one back in and see what happens.