Fluctuating tail lights - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

 
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post #1 of 5 (permalink) Old Dec 7th, 13, 9:46 PM Thread Starter
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Rich
 
Join Date: Nov 2013
Location: Burlington, NJ
Posts: 912
Fluctuating tail lights

Just got back from the last event of the year (local Christmas tree lighting ceremony & parade) before garaging the car for the winter, and a friend told me that my taillights were out. A quick check showed that I had functioning turn signals, but no rear running lights or brake lights.

Pulling in to he neighborhood, idling to the driveway, then up and in to the garage, my neighbor comes over to tell me that the rear lights were out except when I stopped to let my daughter out to open the garage, and they went dim and subsequently out as I accelerated ip the drive and in to the garage.

Bad ground, perhaps?

Not sure if this is related, but I did notice the stereo runs fine, and after 10 minutes or so, I can hear a growing crackle that is in time with the coil (I think)...

-Rich

1968 Chevelle Malibu 454, mild cam, 30 over, 12-bolt 3.73 rear
1972 Chevelle Malibu 350, radical cam, 30 over, 10-bolt 3.55 rear
2007 Mustang GT, 4.6L (281), Stock
There are no Ford vs. Chevy wars in my garage. It's all U.S. muscle.
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post #2 of 5 (permalink) Old Dec 8th, 13, 5:29 PM
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Joe
 
Join Date: Aug 1998
Location: Lincoln, NE
Posts: 4,477
Re: Fluctuating tail lights

Rich--I've added my thoughts in bold...

Just got back from the last event of the year (local Christmas tree lighting ceremony & parade) before garaging the car for the winter, and a friend told me that my taillights were out. A quick check showed that I had functioning turn signals, but no rear running lights or brake lights. So were your rear turn signals working at that point? Brake lights in these cars use the same filaments and wiring as the turnsignals. Tail lights are on a separate circuit from the stop/turn circuit.

Pulling in to he neighborhood, idling to the driveway, then up and in to the garage, my neighbor comes over to tell me that the rear lights were out except when I stopped to let my daughter out to open the garage, and they went dim and subsequently out as I accelerated ip the drive and in to the garage.

Bad ground, perhaps?

never a bad idea to check grounds, but almost sounds like a loose or corroded harness connector. The vibration/jolt of doors opening/accelerating can make/break an intermittent coonection. Start inspecting things, i.e. the rear lighting harness connector in the trunk.

Not sure if this is related, but I did notice the stereo runs fine, and after 10 minutes or so, I can hear a growing crackle that is in time with the coil (I think)...
connections and integrity of grounds to start ...

-If you don't stand for something, you'll fall for anything.
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post #3 of 5 (permalink) Old Dec 9th, 13, 8:49 AM Thread Starter
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Rich
 
Join Date: Nov 2013
Location: Burlington, NJ
Posts: 912
Re: Fluctuating tail lights

Thanks for the feedback! I couldn't get to the car yesterday, but plan to over the next few evenings.

I don't know for sure if the rear turn signals were working at that point. My wife said they were when she looked, but it is possible she misunderstood me. When I put the hazards on, the dash turn signal indicators just came on solid despite having worked properly 40 minutes before. Individually, the turn signal indicators blinked as expected (non hazard mode).

My brother-in-law who has a '69 GTO and has rebuilt it twice (and it is in pieces all over his home as he got stalled -for some time now- putting it back together after replacing the frame) texted me with:
"Fuse block bolt will loosen.. Making bad connections to the female side of block on engine side... Exactly what you describe are symptoms of that, may have to split the block and clean it.. Typical A-body. Also, take a needles nose and check the fuse holders too. Remove fuses pinch holder, reinstall fuses. Cars hate to sit.. Something is moist or dirty.. No big deal."

Sounds like I've got some checking to do.

I've gotta say that so far, I have had nothing but great experiences with the classic car community (on here, in person with local folks, with the people I've bought cars from, etc). It's amazing and refreshing to experience!

1968 Chevelle Malibu 454, mild cam, 30 over, 12-bolt 3.73 rear
1972 Chevelle Malibu 350, radical cam, 30 over, 10-bolt 3.55 rear
2007 Mustang GT, 4.6L (281), Stock
There are no Ford vs. Chevy wars in my garage. It's all U.S. muscle.
Proc is offline  
 
post #4 of 5 (permalink) Old Dec 31st, 13, 10:47 AM Thread Starter
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Rich
 
Join Date: Nov 2013
Location: Burlington, NJ
Posts: 912
Re: Fluctuating tail lights

I checked the wiring, and everything looked solid. Car started up right away and all lighting was functioning as it should. Interestingly, the turn signals were blinking faster than I remembered, so I checked them all and they were all visibly working.

Afterwards, while checking out the wiring under the dash (to determine why the electric cooling fans were not working), I discovered someone wired in a Viper300 alarm system at one point, and at another point someone partially removed it. Figuring that would only cause problems, I removed the rest of it and cleaned up the wiring somewhat. I still have to clean the ground for the fuse block, but I will have to drive the car around for a bit to see if the problem comes back.

1968 Chevelle Malibu 454, mild cam, 30 over, 12-bolt 3.73 rear
1972 Chevelle Malibu 350, radical cam, 30 over, 10-bolt 3.55 rear
2007 Mustang GT, 4.6L (281), Stock
There are no Ford vs. Chevy wars in my garage. It's all U.S. muscle.
Proc is offline  
post #5 of 5 (permalink) Old Jan 15th, 14, 5:00 PM Thread Starter
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Rich
 
Join Date: Nov 2013
Location: Burlington, NJ
Posts: 912
Re: Fluctuating tail lights

I forgot to follow up on this.. The last week of December, I traced back and pulled out all of the wiring related to the Viper alarm system. I found that the wires were cut off leading to the horn, among other crazy things. It's all out and the wiring is cleaned up. So far, everything has been behaving very well. I still have to pull the main ground bolt, clean it up, and tighten it back down.. just to be on the safe side.

1968 Chevelle Malibu 454, mild cam, 30 over, 12-bolt 3.73 rear
1972 Chevelle Malibu 350, radical cam, 30 over, 10-bolt 3.55 rear
2007 Mustang GT, 4.6L (281), Stock
There are no Ford vs. Chevy wars in my garage. It's all U.S. muscle.
Proc is offline  
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