tail light oddity after on frame bed restore

[hplacecf]

hi.

1977 chevrolet c10 stepside.

did an on frame restore of the bed.
took off the steps, fenders, tail gate and front box panel, removed and replaced bolts and nuts.
shifted stuff around to get rid of rust, and then paint.

starting to put it all together.

started with the tail lights. turned on the lights and the tail lights worked fine.

but, if I turn on the left blinker, the left blinker turns off and on completely (even with tail lights on - it goes completely off), and the right side backup light appears to blink in time with the left blinker. ?!?!?!?!?

not sure what is going on.

then, I happened to move the bed slightly and the tail lights went off completely.

I moved the bed again and they came on.

any ideas?

maybe a ground wire?

I searched the forum and did not find anything. I do not see any loose wires.

thanks

[72freak]

Should be grounding.

[J Knight]

Put a ground strap from the bed to the frame. The tail lights are designed to ground to the bed so you need good contact from bed to frame.

[hplacecf]

Originally Posted by J Knight

Put a ground strap from the bed to the frame. The tail lights are designed to ground to the bed so you need good contact from bed to frame.

thanks.

I will give that a try and report back.

[1slo_camaro]

There should have been a ground wire bolted to the passenger side where the light housing bolts in

[walkerb]

I also put a braided ground strap from bed to cab to solve my taillight issue.

[mgchevyparts]

Absolutely is a bad ground

[hplacecf]

made some progress.
thanks for the help.

definitely was/is a ground issue, but still not working 100%.

So, based upon the advice I received here (thanks again!) I attached a ground strap:

from the bolt that sticks out from the bed on the driver side at the rear bottom (and appears to be used for a bed ground wire used for the lights on the driver side of the bed)
to the frame.

Once I did that, I instantly had taillights on again. Even when I moved the bed around (bed bolts are on, but not tightened down yet).

To double check, I disconnected one end of the ground strap and I immediately lost the tail lights until I moved the bed around - so this proved that the ground strap was helping.
I attached the strap and had tail lights again wherever the bed was moved around to - good so far.


But, my issue now is this:

if I put on the 4 way flashers with the lights on,
the passenger side flashes between low light (as it should with lights on) to bright light (as it should with a blinker or 4 ways flashers) - so the passenger side is good.

but,
the driver side tail light goes dark - no low light for taillight, and no bright light for flashing - in time with the passenger side light.
same thing happens if I put on the passenger blinker.

If I put on the driver blinker, the driver blinker does blink, but it goes from all dark to low light (tail light on brightness) - no bright blinker light.

Do I need multiple grounds?

[79Betty]

All 4 of my back end lights are grounded seperatly. Light housing to bed that is all. No straps. License lights self grouding in bumper. Mines fleetside.
Posted via Mobile Device

[1slo_camaro]

dumb question dude.... have you checked all the bulbs and make sure you dont have a busted filament? since thats how you get the low and bright light is from 2 filaments... maybe that could be a contributing factor. these trucks are fairly simple with electric since you dont have 10 modules controlling your lights. its a simple circuit just have to find the basics. but like i said check your bulbs and make sure you dont have any busted filaments... maybe swap bulbs from one side to the other just to check

[hplacecf]

Originally Posted by 1slo_camaro

dumb question dude.... have you checked all the bulbs and make sure you dont have a busted filament? since thats how you get the low and bright light is from 2 filaments... maybe that could be a contributing factor. these trucks are fairly simple with electric since you dont have 10 modules controlling your lights. its a simple circuit just have to find the basics. but like i said check your bulbs and make sure you dont have any busted filaments... maybe swap bulbs from one side to the other just to check

Yes, I did check the bulb (and thanks for mentioning it, as it is the simple things we often overlook...).
The bulb was fine, and I even swapped it out with another one to test - same thing.




One thing for sure, adding the ground strap did make the tail lights brighter (when they work...).


One additional factor that I did not mention was that when I took the bed apart I also unplugged the tail lights where they plug into the outside of the stepside bed. I wonder if I messed up a wire or internal plug connection somehow (though they look ok to me). The wiring looks old and the covering is somewhat brittle.

It looks like one of the plugs has 2 wires (the top plug), and the other plug (lower plug) has just 1 green wire.

Any other ideas are welcome from anyone. I am at a loss here.

[79Betty]

Groud the wires seperatly. Put a strap from bed to frame for good measure. It's grounding through the light itself which is why the work, kinda. Also i'd hardwire that plug out... Since you're bever gonna take the bed off this is a good time to get rid of it...
Posted via Mobile Device

[Rich84]

I had similar issues with my tailights on my stepside..I added a ground from inside one of the tailights to the frame and all my trouble went away.

[hplacecf]

Originally Posted by Rich84

I had similar issues with my tailights on my stepside..I added a ground from inside one of the tailights to the frame and all my trouble went away.

Originally Posted by 79Betty

Groud the wires seperatly. Put a strap from bed to frame for good measure. It's grounding through the light itself which is why the work, kinda. Also i'd hardwire that plug out... Since you're bever gonna take the bed off this is a good time to get rid of it...
Posted via Mobile Device

thanks for the advice.

I will try that and report back.

[hplacecf]

Problems fixed!

Thanks to all that provided advice!

Write up below is for anyone else in the future who might have these issues.


I think the problems were caused by me taking things apart and painting them - inlcuding painting the frame and the stepside tail light housings.

(1)
What I think had originally been the main working 'ground' for the tail lights was the bottom of the bed up against the top of the unpainted frame - so there was metal to metal contact. I could not find any other ground connecting bed to frame.

So, once I painted the frame I lost that frame to bed 'ground' since there was no longer metal to metal contact - unless I moved the bed around and hit a sweet spot of metal to metal still left somewhere.

The fix for that was to add a bed to frame ground strap. That helped provide a main ground again and took care of the issue with one of the tail lights - but the other tail light was still not right.


(2)
What I think was an additional 'tail light ground' was where the one stepside tail light housing connected to the bed where there was paint worn away on both - so there was metal to metal contact.

So, once I painted the tail light housing and bed (where they connect), the one tail light must have been more sensitive 'ground wise' and the secondary ground was lost causing me odd issues with one tail light (even though the other tail light worked fine after adding the ground strap).

The fix for that was to add a ground wire from the metal plate inside the tail light housing (the one with issues) to the ground strap I had previously installed. Once I did that the tail light worked as it should.

So, in my case, I needed multiple grounds.

In addition to the tail lights now functioning as they should, they are brighter (in a good way). Thinking back, when I first got the truck (off of ebay, don't know the true history of the truck) I noticed the tail lights did not seem bright, though the head lights and front parkling lights were bright. Now I know it was the lack of a strong ground.