quick headlight question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

steverino66 · 09-29-2009, 09:41 PM

I'm trying to get headlights/taillights going for the first time - dash light switch is new, verified all the bulbs are good in another vehicle but can't get the lights to come on. I have the hood off, so no parking lights hooked up in front; just spliced in plug for tilt steering column but the column is still out of truck. Am I missing a basic connection with those pieces out (I checked all the light plugs and grounds but haven't chased any voltage in the wires)?

**ChiefRocka** · 09-29-2009, 09:54 PM

Time to start checking for power there buddy.

Do you have constant power at headlight switch ? Do you have power coming into the truck from the horn-relay ? Does it start/run ?

steverino66 · 09-29-2009, 10:04 PM

I got the dome light to work from the headlight switch by twisting the knob, I'm using the stock dash ignition switch, battery is up, truck will start. Probably just missing something obvious in the light circuit beyond the dash.

**ChiefRocka** · 09-29-2009, 10:08 PM

Fuses cool ?

Check firewall connection...

markeb01 · 09-29-2009, 10:57 PM

The dome light is hot all the time, and the headlight switch activates the light by closing the ground side. You could still have a problem with power getting to the switch, but not likely if the engine will start.

You might also want to check the headlight plug grounds with a continuity tester back to the negative battery cable. Depending solely on sheetmetal to return the electricity to ground isn't all that effective. I had random dim head and tail light problems for years, and built in redundant grounding which eliminated the problems.

I run all the head and tail light grounds to a common post on each end of the truck, and connect those with separate wires directly to the the frame right below the battery. The negative battery cable attaches to the engine block, and a second battery cable goes from the engine block to the frame, connecting all the chassis ground wires.

Rule of thumb - there should never be more than one source of power - and - you can't have too many grounds.

steverino66 · 09-30-2009, 10:27 AM

Okay, guys, I appreciate the replies; you've given me a starting direction. Didn't check fuses and I know the gauge lights are dead also; engine's not grounded to frame yet. I'll start chasing wires.

steverino66 · 10-04-2009, 08:08 PM

SO… I swapped out the dimmer switch and got the headlights working high beam and low, but somehow managed to kill the dome light and dash lights in the process (they were working before headlights but not now)! High beam dash light works.
Still have no taillights - checked/tightened light plugs everywhere and visually checked wires all around, checked the tail light bulbs swapping them into my El Camino; it's definitely not the fuses, I swapped them around to check, checked that dome light bulb is still good also. So WTF?
This will be a continuing battle for next weekend, any thoughts definitely appreciated.

09-29-2009, 09:41 PM	#1
steverino66 Registered User Join Date: Oct 2005 Location: oklahoma Posts: 663	quick headlight question I'm trying to get headlights/taillights going for the first time - dash light switch is new, verified all the bulbs are good in another vehicle but can't get the lights to come on. I have the hood off, so no parking lights hooked up in front; just spliced in plug for tilt steering column but the column is still out of truck. Am I missing a basic connection with those pieces out (I checked all the light plugs and grounds but haven't chased any voltage in the wires)?

09-29-2009, 09:54 PM	#2
ChiefRocka Hollister, CA. Join Date: Sep 2006 Location: Hollister, Ca. Posts: 6,150	Re: quick headlight question Time to start checking for power there buddy. Do you have constant power at headlight switch ? Do you have power coming into the truck from the horn-relay ? Does it start/run ? __________________ John What the Heck is that ?? CURRENT BUILDS: 62 BurbMaster Other Builds: My '63 C-10,LWB,CC,BBW '06 HD StrAight Axle Swap Father/Son '67 C-20, LQ9,4L80,Bagged,8-Lugger !!Good Friend Richard's Build AMERICAN CUSTOMS & CLASSICS (831) 630-1965 www.ACCHOLLISTER.com ACC on FACEBOOK "Rest in Peace, Mom & Dad ... I will see you again someday!"

09-29-2009, 10:04 PM	#3
steverino66 Registered User Join Date: Oct 2005 Location: oklahoma Posts: 663	Re: quick headlight question I got the dome light to work from the headlight switch by twisting the knob, I'm using the stock dash ignition switch, battery is up, truck will start. Probably just missing something obvious in the light circuit beyond the dash.

09-29-2009, 10:08 PM	#4
ChiefRocka Hollister, CA. Join Date: Sep 2006 Location: Hollister, Ca. Posts: 6,150	Re: quick headlight question Fuses cool ? Check firewall connection... __________________ John What the Heck is that ?? CURRENT BUILDS: 62 BurbMaster Other Builds: My '63 C-10,LWB,CC,BBW '06 HD StrAight Axle Swap Father/Son '67 C-20, LQ9,4L80,Bagged,8-Lugger !!Good Friend Richard's Build AMERICAN CUSTOMS & CLASSICS (831) 630-1965 www.ACCHOLLISTER.com ACC on FACEBOOK "Rest in Peace, Mom & Dad ... I will see you again someday!"

09-29-2009, 10:57 PM	#5
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: quick headlight question The dome light is hot all the time, and the headlight switch activates the light by closing the ground side. You could still have a problem with power getting to the switch, but not likely if the engine will start. You might also want to check the headlight plug grounds with a continuity tester back to the negative battery cable. Depending solely on sheetmetal to return the electricity to ground isn't all that effective. I had random dim head and tail light problems for years, and built in redundant grounding which eliminated the problems. I run all the head and tail light grounds to a common post on each end of the truck, and connect those with separate wires directly to the the frame right below the battery. The negative battery cable attaches to the engine block, and a second battery cable goes from the engine block to the frame, connecting all the chassis ground wires. Rule of thumb - there should never be more than one source of power - and - you can't have too many grounds.

09-30-2009, 10:27 AM	#6
steverino66 Registered User Join Date: Oct 2005 Location: oklahoma Posts: 663	Re: quick headlight question Okay, guys, I appreciate the replies; you've given me a starting direction. Didn't check fuses and I know the gauge lights are dead also; engine's not grounded to frame yet. I'll start chasing wires.

10-04-2009, 08:08 PM	#7
steverino66 Registered User Join Date: Oct 2005 Location: oklahoma Posts: 663	Re: quick headlight question SO… I swapped out the dimmer switch and got the headlights working high beam and low, but somehow managed to kill the dome light and dash lights in the process (they were working before headlights but not now)! High beam dash light works. Still have no taillights - checked/tightened light plugs everywhere and visually checked wires all around, checked the tail light bulbs swapping them into my El Camino; it's definitely not the fuses, I swapped them around to check, checked that dome light bulb is still good also. So WTF? This will be a continuing battle for next weekend, any thoughts definitely appreciated.



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