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Old 08-11-2020, 04:16 PM   #1
69Tom
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74 step tail lights stopped working

I've been doing a bunch of reading through threads on here, but wanted to make sure best way to do this.

Basically, last night my running tail lights stopped working. I had an issue with the truck where the truck wouldn't shut off. After much troubleshooting, I determined the moron working on my exhaust pushed the positive battery cable at the starter into the terminal with the ignition wire, so I was getting constant voltage to the coil and it fried the coil. I adjusted the cable, replaced the coil, and issue solved. Except now my tail lights don't come on.

Brake lights, dash lights, side marker lights and directionals all work.

I partially dropped my tilt column to check my ignition switch when I was dealing with the coil issue (thinking the ignition switch was the problem), but really didn't move much of anything around other than the switch. Not sure if I somehow pinched a wire.

As such, and from my reading, this is not a fuse issue, and most likely a ground issue, correct?

Also, I'm guessing it's not a bulb as both sides are out?

I'm in AZ, so not much rust here, but stuff still does get rust, so not sure if the mount to body ground on the tail light housing is the issue.

Just weird it happened all of a sudden while I had this coil issue.
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Old 08-11-2020, 09:23 PM   #2
dmjlambert
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Re: 74 step tail lights stopped working

I recommend always check the bulbs first. Then use a multimeter or test light probe to check the bulb sockets for presence of voltage. If you can also test that the bulb socket is grounded using the same tester.
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Old 08-11-2020, 09:29 PM   #3
69Tom
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Re: 74 step tail lights stopped working

Thanks. I’ll do that first and go from there who knows last time they were changed.
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Old 08-12-2020, 06:37 AM   #4
RustyPile
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Re: 74 step tail lights stopped working

Quote:
Originally Posted by 69Tom View Post
I've been doing a bunch of reading through threads on here, ...........<snip>............ from my reading, this is not a fuse issue, and most likely a ground issue, correct?

Also, I'm guessing it's not a bulb as both sides are out?

I'm in AZ, so not much rust here, but stuff still does get rust, so not sure if the mount to body ground on the tail light housing is the issue.

Just weird it happened all of a sudden while I had this coil issue.
You're reading way too much into this problem.. And stop all the guessing. The VERY first thing to check is the tail light fuse.. Don't guess at it, nor should you just look at the fuse.. Voltage should appear on both ends of the fuse --using a test light or DVM, check for voltage on both ends of the fuse.. If voltage is present, remove the tail light bulbs and check for voltage in the socket.. If voltage is present, either a bad bulb or bad connection between the bulb and socket is the problem... If you suspect a bad ground for the bed, for testing purposes, make up a looooong jumper with alligator clips on each end, long enough to reach between the battery negative post to the light housing.. Connect one end of the jumper to the negative post and the other end to the light housing.. When you have working lights, remove one end of the jumper.. If the lights go out, you have a bad ground.. If the lights continue to work, the ground path is good to go..
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Old 08-12-2020, 07:43 AM   #5
VetteVet
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Re: 74 step tail lights stopped working

Quote:
Brake lights, dash lights, side marker lights and directionals all work.
I'd rule out the ground issue based on this.

The side marker lights are part of the tail light circuit (I think) so that means you should have power on the brown wire for the tail lights which only leaves the tail light bulb filiments. I would disconnect the rear connector and check the tail light wire (brown), for power and If you have it, that only leaves the bulbs.

I like the troubleshooting that's been given by everyone so far, very good.
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