Brake light issues.

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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cavscout217
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Brake light issues.

Post by cavscout217 » Tue Jun 20, 2017 5:27 pm

I bought this A2 over the weekend and this morning I realized that the brake lights aren't working properly. With the light switch in "Stop Lights" or "Service Drive" the right light comes on and stays on only flickering when the pedal is depressed, the left light does nothing at all. Both turn signals do work. I have seen in other posts here and on other forums that the turn signal switch is sometimes a cause for brake light issues. Any suggestions?
Thanks in advance,
Mike Haines
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Mike Haines
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Kurt Lesser
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Re: Brake light issues.

Post by Kurt Lesser » Wed Jun 28, 2017 5:37 am

The stop lamps and tube signals are separate bulbs in M series trucks. I would venture a guess that if one doesn't work at all then you have a bad bulb. If the other only flickers then there's a good possibility that the brake light switch is worn and failing. There not hard to change out but time consuming to say the least. You'll remember words you probably haven't used in a while! LOL

You'll want to check the grounding on the brake light housings inside and out because they get corroded over the years and both mounting bolts need to be in place and there should be star washers on them to insure good electrical bonding to the body. Give you wiring harness a good look over too, they do get brittle with age and make sure that the connectors themselves are firmly pushed together. A little electricians anti-oxidant grease on them will make them go back together more easily and help exclude water from getting into them. Another good lubricant for rubber is Dow-Corning DC-4 available from places like McMaster-Carr or Aircraft Spruce.
Kurt Lesser
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