need help, lights are crazy - The 1947 - Present Chevrolet & GMC Truck Message Board Network

WORNBRAKES · 06-09-2002, 04:39 PM

My brake lights are dimmer than normal. Front parking lights come on when you press brake pedal. Turn signals are strong. Suspect a bad ground somewear but don't know were to start. If any one can help, I would apreciate it. Thanks.

Mario

WORNBRAKES · 06-09-2002, 05:40 PM

Got power to the fuse panel and all the way pack. What would only affect the brake and tail lights but not the turn signals?

Mitzki5 · 06-09-2002, 05:57 PM

Check your blinker fluid! hehehehe

Just kidding. Sorry, but I can't help you. You came to the right place for the answer though. These guys and gals know their stuff. Good Luck

*Zkast* · 06-09-2002, 06:04 PM

Make sure you dont have a 1056 (single element bulb) in place of a 1157 (double element bulb). It will cause your tail lights to illuminate whenever the brake lights are powered. It's back feeding the parking light circuit with power from the brake lights.

If the 2 rear bulbs are fine, start looking into the turn signal switch. Your brake light power is fed through the switch as is your turn signals and parking light circuit. If the switch is shorted in some area's it will also allow a backfeed problem.

daveo68 · 06-09-2002, 06:08 PM

Had a grounding problem on my truck last year.Took three days to find.Finally pulled tail light lenses out,had some bolts loose on one of the tail light assemblies.I had basically same symptons.

WORNBRAKES · 06-09-2002, 06:36 PM

Thanks for the diff aproaches. I have 1157 bulbs in the rear. I am still cahasing wires and finding some exposed wires that may bee bleeding into each other. Going to fix those, check fluid lol, and keep troubleshooting.
Thanks,
Mario

Mountain Man · 06-09-2002, 07:24 PM

I also have the exact same problem. When I apply the brake, my right front (passenger side) signal light goes on. I am also in need of a fix.

blue_69 · 06-09-2002, 07:43 PM

that problem is either a bad ground, wires melted together, or possibly a bad signal switch . I'm not 100% sure on the signal switch i havent had to mess with one in a while but i have seen that happen on newer cars.

chevy72402 · 06-09-2002, 07:58 PM

It sounds like a bad ground and the power is backfeeding through the park lights to find a good ground.

WORNBRAKES · 06-09-2002, 08:14 PM

I started aft and have been working forward. About to start on the turn signal switch. Any ideas of wear to start here b/c I realy don't want to rip everything apart. I replaced all of the old splices in the back and added good wire were there was chafed wires. I will just keep chasing wires. Aint that a b$&ch.
Thanks for all the advice,
Mario

chevy72402 · 06-09-2002, 08:20 PM

it still does it after you replaced those wires? and you checked your grounds for rust and stuff?

71GMC_3/4T · 06-10-2002, 12:15 AM

Put a 2x4 between the under side of the dash and the pedal. Either that or find your brake switch and pull it back far enough to turn it on.
Then get a volt meter and measure for any voltage drops in all the areas where the ground should be flowing. If you measure any volts over 1 or so, you've found a bad ground connection.
By this I mean check the voltage between the taillamp housing and the bed. Then check the bed to the frame. Then check the frame back to the (-) battery terminal. Somewhere you should find your problem if it's a bad ground. If the back doesn't expose the problem, check the front. You can also use a black wire clipped to the battery (-) as a reference point. All "grounds" should read zero volts back to the (-) terminal. Anywhere you find voltage on a frame part means there's something wrong.
If you don't have a volt meter, you can use a 12V lamp. If it lights up, even a little, you're getting real close to solving your ground problem.
Hope this helps.
Keep us posted.
Oh another thing popped into my head... Check your sockets for the taillight bulbs to be sure they're getting a good ground to the shell of the bulb. That type of problem is a real ***** to find. Troubleshoot it with a piece of wire to ground the shell of the bulb to the chassis (or even (-) battery terminal.

WORNBRAKES · 06-10-2002, 12:56 AM

It' funny. I replaced the aft harnes about three monthes ago. Today, I ended up replacing all the wires from the fire wall back to the aft harness. Found some of the wires to be chafed and grounded to the frame and eachother were the clips are. Also found some bad splices about mid body with broken wires. After all that I had the wife help with signals and lights. Found tail lights to work ok, left turn signal ok, but when you use right signal you loose the tail light on that side.
When I was done for the night, I started the truck to charge the bat and about every 3 seconds I would hear a tick tick from the alt. That is unusual. I'm thinking in the morning I will check the alt first thing. Then I will check all wires under dash again. So far I seem to have power wear I should once the wires were replaced.
Thanks to all members for advice,
Mario

Hooter · 06-10-2002, 02:16 AM

I know this has already been said but it sounds to me like you have a single element bulb in a doublke element socket or your truck is possesed by Satan

WORNBRAKES · 06-10-2002, 04:22 PM

I now have the dash pulled apart [going to install dash pad while I am here(thanks LeRoy)] chasing wires under there. I am finding that when I turn on the lights, my signals are charged at that point. That don't seem right. They should be charged when I turn on accesories and use the signal.It has been said before but do you think my turn switch is bad? If so how is that replaced? I hope I find a bad wire. Just sounds a lot easier.
Thanks

WORNBRAKES · 06-10-2002, 05:19 PM

determined switch is bad. When I turn on signal left or right they both get power and are blinking. If I dont have acc on and I turn lights on I get no taqil lights. If I have lights on no acc and use turn signals I get tail lights. Going to try the yard for a switch If not wear is a good place to get one fast?

71GMC_3/4T · 06-10-2002, 07:08 PM

Napa has good ones. Unfortunately they may not have the exact connector you have. They do give you an adapter cable, but I extracted the pins and rewired it the way I wanted it. Don't mix up the wires if you do this though.
My truck had a messed up turn signal switch when I got it. Lucky for me it didn't cancel and I shotgunned the whole thing. While I was changing it out, I found where some idiot had spliced a couple of the wires in the switch harness. That would have taken me hours to find...

WORNBRAKES · 06-10-2002, 11:08 PM

Replaced the switch. Looks like it needed it, as you can see. Still have same prob. I might have hazards again thanks to new switch. With rear bulbs installed, I get no tail lights unless I turn on the signals with no accesory power.Funny. I can tell this by the neat little lights on the tow harness. Never thought I would need them.If I turn on lights, now accesory power and remove bulbs, I then get power to on pin whitch tells me that would be tail lights. Does that make sence? Maby the pins in the taillamp harness are grounding? I can't find any wires under the dash to be bad. I have been using the Haynes and a spare under dash harness to chase these wires down. Does any one know of a better manual for wire diagrams? I need one that tells you weither the wire is power or ground. Haynes just shows color, size and wear they go to and from. Well back to the truck I go, I need to tackle this.
Thanks,
Mario

WORNBRAKES · 06-10-2002, 11:11 PM

I seemed to get the dash pad installed though. lol

Longhorn Man · 06-10-2002, 11:43 PM

All the wires are hot at one oint or another...the body is the only ground you need.
Check this link for schematics.

WORNBRAKES · 06-11-2002, 02:17 AM

I think I have the problem issolated. The wife walks in the garage to bull sh!t and after shee is done I try to explain it all to her. Me, I am confused, frustrated, pissed and on my way to being drunk at this point. I explained everything to her using the spare harness that I use to make it easy to chase wires. Finaly she said "wear is the main problem", I told her it was that I am getting power to all 4 tail wires wwith the lights on when only the wire from the light switch should have it. She told me to disconnect it and then check it. I did and everything was as it should be. So her little smart a$$ figured it out after I have spent a day and a half lookking at it. lol
Thanks for all the help, I am going to the yard tomarow to find the firewall plug. I have a spare under dash, so I hope the truck is on the road in the afternoon.
Back to the basics for me!

WORNBRAKES · 06-29-2002, 01:22 PM

ttt

hanssolo · 06-29-2002, 03:24 PM

Would it be safe to say bad grounds are 80% of old vehicle electrical problems? Also, all you guys with pretty flashing pictures on your posts, I'm jealous! I want one too!

elf w/capital T · 05-15-2011, 06:53 PM

damn, im having this problem now, my brakes light are on, my front passenger side turn signal stays on too, but with the blinker on, it works as advertised. hmmm bad ground somewhere, when i get it i WILL post. thanks for the help everyone though

Longhorn Man · 05-15-2011, 08:04 PM

sweet... 9 year old threads rock!
Elf, by chance, is the flasher removed for your 4 ways, and the button broken off, in the on position?

06-09-2002, 04:39 PM	#1
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	need help, lights are crazy My brake lights are dimmer than normal. Front parking lights come on when you press brake pedal. Turn signals are strong. Suspect a bad ground somewear but don't know were to start. If any one can help, I would apreciate it. Thanks. Mario __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-09-2002, 05:40 PM	#2
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	Got power to the fuse panel and all the way pack. What would only affect the brake and tail lights but not the turn signals? __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-09-2002, 05:57 PM	#3
Mitzki5 "TRUCKLESS" Join Date: Jan 2002 Location: Tuscola IL Posts: 457	Check your blinker fluid! hehehehe Just kidding. Sorry, but I can't help you. You came to the right place for the answer though. These guys and gals know their stuff. Good Luck __________________ Mitzki5 No longer have an old truck! But always looking for another one!

06-09-2002, 06:04 PM	#4
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Make sure you dont have a 1056 (single element bulb) in place of a 1157 (double element bulb). It will cause your tail lights to illuminate whenever the brake lights are powered. It's back feeding the parking light circuit with power from the brake lights. If the 2 rear bulbs are fine, start looking into the turn signal switch. Your brake light power is fed through the switch as is your turn signals and parking light circuit. If the switch is shorted in some area's it will also allow a backfeed problem. Last edited by Zkast; 06-09-2002 at 06:08 PM.

06-09-2002, 06:08 PM	#5
daveo68 Senior Member Join Date: Dec 2001 Location: Lexington,NC Posts: 503	Had a grounding problem on my truck last year.Took three days to find.Finally pulled tail light lenses out,had some bolts loose on one of the tail light assemblies.I had basically same symptons. __________________ 68 C-10 Custom LWB 307 V8 Lexington,NC davideowens@lexcominc.net God Bless America

06-09-2002, 06:36 PM	#6
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	Thanks for the diff aproaches. I have 1157 bulbs in the rear. I am still cahasing wires and finding some exposed wires that may bee bleeding into each other. Going to fix those, check fluid lol, and keep troubleshooting. Thanks, Mario __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-09-2002, 07:24 PM	#7
Mountain Man Registered User Join Date: Jan 2002 Location: Calgary, Alberta, Canada Posts: 451	I also have the exact same problem. When I apply the brake, my right front (passenger side) signal light goes on. I am also in need of a fix. __________________ 72 C10 Cheyenne Super Full trim Factory tach dash A/C dash Factory tilt 350 / 350 power train - with Edelbrock components.

06-09-2002, 07:43 PM	#8
blue_69 someday Join Date: Dec 2001 Location: canastota,new york Posts: 629	that problem is either a bad ground, wires melted together, or possibly a bad signal switch . I'm not 100% sure on the signal switch i havent had to mess with one in a while but i have seen that happen on newer cars.

06-09-2002, 07:58 PM	#9
chevy72402 FARMER/RANCHER Join Date: Apr 2001 Location: SD Posts: 597	It sounds like a bad ground and the power is backfeeding through the park lights to find a good ground. Attached Images __________________ 1972 chevy super, long box, 402 big block (2,000 miles on rebuild) 2wd tach, tilt, tool box on bedside, a/c, sliding rear window, orange and white. 1972 Chevy Blazer 2wd, tach, tilt, a/c, my first engine overhauling experience, Orange, with white top 2006 Gmc Sierra, XM, Z-71, dark blue, onstar, leather, rear entertainment (audio only) heated seats, (the wife loves that feature) upgraded tires immediately after purchase to Goodyear Wrangler AT/S (hate those rock throwers that come from the factory) BWC

06-09-2002, 08:14 PM	#10
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	I started aft and have been working forward. About to start on the turn signal switch. Any ideas of wear to start here b/c I realy don't want to rip everything apart. I replaced all of the old splices in the back and added good wire were there was chafed wires. I will just keep chasing wires. Aint that a b$&ch. Thanks for all the advice, Mario __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-09-2002, 08:20 PM	#11
chevy72402 FARMER/RANCHER Join Date: Apr 2001 Location: SD Posts: 597	it still does it after you replaced those wires? and you checked your grounds for rust and stuff? Attached Images __________________ 1972 chevy super, long box, 402 big block (2,000 miles on rebuild) 2wd tach, tilt, tool box on bedside, a/c, sliding rear window, orange and white. 1972 Chevy Blazer 2wd, tach, tilt, a/c, my first engine overhauling experience, Orange, with white top 2006 Gmc Sierra, XM, Z-71, dark blue, onstar, leather, rear entertainment (audio only) heated seats, (the wife loves that feature) upgraded tires immediately after purchase to Goodyear Wrangler AT/S (hate those rock throwers that come from the factory) BWC Last edited by chevy72402; 06-09-2002 at 08:25 PM.

06-10-2002, 12:15 AM	#12
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Put a 2x4 between the under side of the dash and the pedal. Either that or find your brake switch and pull it back far enough to turn it on. Then get a volt meter and measure for any voltage drops in all the areas where the ground should be flowing. If you measure any volts over 1 or so, you've found a bad ground connection. By this I mean check the voltage between the taillamp housing and the bed. Then check the bed to the frame. Then check the frame back to the (-) battery terminal. Somewhere you should find your problem if it's a bad ground. If the back doesn't expose the problem, check the front. You can also use a black wire clipped to the battery (-) as a reference point. All "grounds" should read zero volts back to the (-) terminal. Anywhere you find voltage on a frame part means there's something wrong. If you don't have a volt meter, you can use a 12V lamp. If it lights up, even a little, you're getting real close to solving your ground problem. Hope this helps. Keep us posted. Oh another thing popped into my head... Check your sockets for the taillight bulbs to be sure they're getting a good ground to the shell of the bulb. That type of problem is a real ***** to find. Troubleshoot it with a piece of wire to ground the shell of the bulb to the chassis (or even (-) battery terminal. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

06-10-2002, 12:56 AM	#13
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	It' funny. I replaced the aft harnes about three monthes ago. Today, I ended up replacing all the wires from the fire wall back to the aft harness. Found some of the wires to be chafed and grounded to the frame and eachother were the clips are. Also found some bad splices about mid body with broken wires. After all that I had the wife help with signals and lights. Found tail lights to work ok, left turn signal ok, but when you use right signal you loose the tail light on that side. When I was done for the night, I started the truck to charge the bat and about every 3 seconds I would hear a tick tick from the alt. That is unusual. I'm thinking in the morning I will check the alt first thing. Then I will check all wires under dash again. So far I seem to have power wear I should once the wires were replaced. Thanks to all members for advice, Mario __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-10-2002, 02:16 AM	#14
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	I know this has already been said but it sounds to me like you have a single element bulb in a doublke element socket or your truck is possesed by Satan __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

06-10-2002, 04:22 PM	#15
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	I now have the dash pulled apart [going to install dash pad while I am here(thanks LeRoy)] chasing wires under there. I am finding that when I turn on the lights, my signals are charged at that point. That don't seem right. They should be charged when I turn on accesories and use the signal.It has been said before but do you think my turn switch is bad? If so how is that replaced? I hope I find a bad wire. Just sounds a lot easier. Thanks __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins



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06-10-2002, 05:19 PM	#16
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	determined switch is bad. When I turn on signal left or right they both get power and are blinking. If I dont have acc on and I turn lights on I get no taqil lights. If I have lights on no acc and use turn signals I get tail lights. Going to try the yard for a switch If not wear is a good place to get one fast? __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-10-2002, 07:08 PM	#17
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Napa has good ones. Unfortunately they may not have the exact connector you have. They do give you an adapter cable, but I extracted the pins and rewired it the way I wanted it. Don't mix up the wires if you do this though. My truck had a messed up turn signal switch when I got it. Lucky for me it didn't cancel and I shotgunned the whole thing. While I was changing it out, I found where some idiot had spliced a couple of the wires in the switch harness. That would have taken me hours to find... __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

06-10-2002, 11:08 PM	#18
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	Replaced the switch. Looks like it needed it, as you can see. Still have same prob. I might have hazards again thanks to new switch. With rear bulbs installed, I get no tail lights unless I turn on the signals with no accesory power.Funny. I can tell this by the neat little lights on the tow harness. Never thought I would need them.If I turn on lights, now accesory power and remove bulbs, I then get power to on pin whitch tells me that would be tail lights. Does that make sence? Maby the pins in the taillamp harness are grounding? I can't find any wires under the dash to be bad. I have been using the Haynes and a spare under dash harness to chase these wires down. Does any one know of a better manual for wire diagrams? I need one that tells you weither the wire is power or ground. Haynes just shows color, size and wear they go to and from. Well back to the truck I go, I need to tackle this. Thanks, Mario Attached Images __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-10-2002, 11:11 PM	#19
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	I seemed to get the dash pad installed though. lol Attached Images __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-10-2002, 11:43 PM	#20
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	All the wires are hot at one oint or another...the body is the only ground you need. Check this link for schematics.

06-11-2002, 02:17 AM	#21
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	I think I have the problem issolated. The wife walks in the garage to bull sh!t and after shee is done I try to explain it all to her. Me, I am confused, frustrated, pissed and on my way to being drunk at this point. I explained everything to her using the spare harness that I use to make it easy to chase wires. Finaly she said "wear is the main problem", I told her it was that I am getting power to all 4 tail wires wwith the lights on when only the wire from the light switch should have it. She told me to disconnect it and then check it. I did and everything was as it should be. So her little smart a$$ figured it out after I have spent a day and a half lookking at it. lol Thanks for all the help, I am going to the yard tomarow to find the firewall plug. I have a spare under dash, so I hope the truck is on the road in the afternoon. Back to the basics for me! __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-29-2002, 01:22 PM	#22
WORNBRAKES Senior Member Join Date: Jul 2001 Location: Hughesville, MD Posts: 1,350	ttt __________________ Mario and Mandy Hughesville, MD 20637 69 C10 305/350 71 K5 Basket case 75 K10 Rescue Parting out 77 MG Midget Parting out 15 6.7L Cummins

06-29-2002, 03:24 PM	#23
hanssolo Registered User Join Date: Sep 2001 Location: central Ill. USA Posts: 447	Would it be safe to say bad grounds are 80% of old vehicle electrical problems? Also, all you guys with pretty flashing pictures on your posts, I'm jealous! I want one too! __________________ 69 C10 longbed: 357c.i. /TH400/3.73s/AC/ beige primer/saving $ for paint ______________________________

05-15-2011, 06:53 PM	#24
elf w/capital T Registered User Join Date: Feb 2011 Location: North Carolina Posts: 994	Re: need help, lights are crazy damn, im having this problem now, my brakes light are on, my front passenger side turn signal stays on too, but with the blinker on, it works as advertised. hmmm bad ground somewhere, when i get it i WILL post. thanks for the help everyone though

05-15-2011, 08:04 PM	#25
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: need help, lights are crazy sweet... 9 year old threads rock! Elf, by chance, is the flasher removed for your 4 ways, and the button broken off, in the on position?

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