turn signals/brake lights woes

[willyp]

Having trouble with turn signals/brake lights. I installed a new painless wiring harness part # 10112 and new tail lamp pigtail and rubber boot harness from classic parts part # 55-152 about 6 months ago. During the day without the running/headlights on the rear turn signals and brake lights work fine without any issues. At night with the running/headlights on the rear running lights work fine but when I step on the brakes the running/brake lights on the driver side go out.

Seems this would be an easy thing to trouble shoot………….wrong!

It is an intermittent problem, all lights work fine for a couple weeks so I am 100% sure everything is hooked up properly, then back to the original fault. To make it worse the problem started on the passenger side lights and now they work fine and the driver side lights now have the fault. Last night the fault reoccurred, when I got home I parked the truck in the driveway without shutting the ignition off, removed the tail light lens and bulb and checked for voltages…………checked out good in all modes. I reinstalled the bulb/lens and drove around for 45 minutes with no issues.

1. I have checked all voltages for tail lights and brake lights/turn signals. All +12 volts when commanded. (running, turning (pulse) 4 way flashers and brake)

2. Installed separate ground straps for each tail light housing to the truck bed, and a new ground strap from the bed to the frame. All grounds locations have been ground down to bare metal and new soldered connectors, sheet metal screws and slight dab of dielectric grease to prevent dirt, moisture and corrosion.

3. Replaced both rear bulbs #1157.

4. Inspected all wires from the fuse box to the tail section for any chaffing or damage, opened up every splice to ensure there are no brakes. No crimp type connectors were used on the truck only solder and heat shrink tubing. If a crimp connector end was used then I also soldered the connector to the wire. Chaff tape and zip ties used to prevent chaffed wires or vibrations.

5. Replaced tail lamp lens gaskets for possible moisture/water .

6. The front running/turn signals work fine with no issues.

This forum is has a huge knowledge base so hopefully someone has been down this road before and can give me some insight to any other solutions.

[protrash64]

You didnt mention, but is the turn signal switch new?

[powerdriver 1958]

I'll bet a better response will be in the electrical forum

[markeb01]

Tail light problems on these old trucks are almost always ground related. In reading all you’ve done and the quality of work, the only potential issue I can see may be the inside of the tail lamp sockets themselves. I looked at the Classic pigtails and see they don’t come with new sockets. If you haven’t done so already, I’d recommend scrubbing the inside of the sockets with either a battery brush or fine sandpaper, then smearing dielectric grease on the walls of the socket. The grease will provide both better contact with the bulb, and keep the socket corrosion free for a long time. The power wires coming in certainly have good contact with the bulb terminals, but if the sockets themselves aren’t clean enough the ground side of the circuit may be intermittently failing between the bulb and the socket. This would keep the return path from reaching the new ground wires you attached to the housings.

If the sockets are already like new, I’d run a full length ground wire from the engine block to the back of the truck and ground the tail light housing wires directly to that. This would eliminate any chance the problem is in the sheet metal or the frame.

If better or additional grounding doesn’t solve the problem, I’d start looking at the turn signal switch. They rarely fail, but the crossover circuit in the turn signal switch is what allows the turn signals to continue functioning when the brake lights are activated. With a 40+ year old electrical component anything is possible.

[willyp]

The turn signal switch was replaced a couple months ago when I installed a new ididit tilt steering column.

As far as the tail lamp sockets, during assembly I used the shot gun bore brush installed in my Dewalt cordless drill to clean the dirt and corrosion from inside the lamp sockets, then I gave them a thin coat of dielectric grease.

During trouble shooting I checked continuity with an external jumper wire and multimeter from the engine block to both tail light sockets. The grounds are good. Do you still think I need another external ground?

[markeb01]

This is truly one of those gremlins that can drive you nuts. You’ve already addressed and repaired or replaced every conceivable trouble spot. The intermittent nature of the problem still leaves me thinking it’s ground related. If the problem was on the power side of the circuit it would indicate a short somewhere, which should quickly deteriorate until it was easy to detect.

From a logical perspective it would seem a separate ground wire from the engine block to the tail light sockets “should” solve the problem.

The Ron Francis catalog contains a troubleshooting tech section with the following information pertaining to grounds:

Ground the negative battery cable to the engine block (not the frame). Let’s say we consider copper is the best conductor used in an automobile and we’ll call that 100%. Brass is only 22%, and steel is only 12-16%.

Use the engine as the primary ground connection and attach the frame, central grounding strip and steel body to the same stud if possible.

The size of the ground wire should be size of the wire feeding it.

Our motto: If it’s goofy, you know it’s a ground. You must have at least one on every electrical item, either through mounting methods or direct wires.

If you are having trouble with one tail light or brake light, the other is not affected unless it has a bad ground.

In conclusion:

1. If it’s goofy, it’s a ground.
2. Everything needs a ground.
3. You can never run too many grounds.
4. Steel will rust so check your grounds regularly.
5. Ground battery to block, block to frame, block to body.

[fixit-p]

You said you checked for voltage at all the lights and you have good readings of +12 volts, I assume you did this when the fault was present. If that's the case the problem is most definitely the ground side or open circuit to ground. You also said you checked for continuity to ground but that test can be misleading because any path to ground will give you a good reading. Next time you have an issue check for voltage at the hot side of the load then check for voltage on the ground side of the load (the taillight housing etc.). If you have voltage present on the ground side it is because the ground is poor or missing (anything over .5 volts on the ground side is an indicator of a poor ground). If you have 0 voltage on the ground side it means you have an open circuit to ground at the load (could be a bad bulb or bad connection from the bulbs shell to the taillight housings socket). These voltage/voltage drop tests will pin point your problem, you can post back the results for interpretation.

[willyp]

thanks fixit-p, ill do it next time i have the problem.

i called painless tech support today.....they pointed the finger at ididit (turn signal switch). then i called ididit and they pointed the finger at painless.................jon from ididit did send me some steering column wiring documents and turn signal, brake light, 4 way flasher diagnostic checks.

[LockDoc]

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You don't mention a ground strap from the engine to the frame. As Markeb01 mentioned in his last post this is an important one...

LockDoc

[willyp]

the battery is grounded to the engine
the frame and front fender is grounded to the engine. each ground strap is 3/4 in wide.
also i have the fire wall grounded to the engine with the same type strap as the rear frame to the body.

[willyp]

been a whole week, still no issues. i hate intermittent problems. we will see tonight.

[willyp]

The fault came back, during the day I realized that the left rear brake, turn and 4 way flasher was not as bright as the right rear. I removed the tail light lenses and noticed the run light filament in the 1157 bulb was illuminating when the brakes, turn signal and flashers were on. I removed the bulb and checked for proper voltages at the pins in all modes. All good so I installed the bulb and it works like a champ…….WTF?

The run light wire originates in the headlight switch and terminates in the rear light socket.

The brake/turn/4 way flasher originates in the turn signal switch and terminates in the rear light socket.

Also, did what fixit-p sugested. i checked for stray voltage at the grounds, when brakes or turn signals are on. left side rear ground was .003 and right side was .012 volts.

Anybody got any ideas?

[fixit-p]

The fact that the run light filament was glowing with out power being applied to it is an indicator that you have a poor ground on that side. The 2 filaments (stop and tail) without a good ground on that side have basically become a series circuit and has found an alternate ground (possibly other taillight, marker light or license plate light).

[willyp]

I was thinking how it could be a grounding problem. I had a similar problem with the reverse light housing I got from the junk yard and after pulling my hair out my dad and I finally figured it out. The bulb socket even though pressed into the housing did not make a good connection to the housing. I ended up using a Dremel tool and grounding the socket and the housing down to bare metal and dropping a big glob of solder to join the socket and housing together. It worked like a champ…..reverse lights!

Back to the Brake lights, all fingers pointed to a bad ground for the tail light but continuity checks from both rear tail light housings to the engine block were always good and i always had the proper voltages. I though back to my reverse light problem. Even thought I cleaned the inside of the bulb sockets well and used dielectric grease plus I added an extra ground wire from the housing to the fender the housings still had a fair share of dirt and corrosion. I removed and marked the 2 housings left and right, then off to do some sand blasting. After I sand blasted the tail light housings I conducted another continuity test on the work bench between the socket and housing……..only this time the right rear housing showed a bad ground between the socket and housing. I dropped a bead of solder around the copper colored socket and the base where they are pressed together on both rear housings….continuity check good!

I put everything back together and it works great. I never thought the sockets themselves could go bad……..also the bad socket was the passenger side, right rear and the driver side left rear was the side that was giving me a fit. Weird grounding gremlins, maybe after 44 years corrosion gets in between the 2 dissimilar metals between the socket and housing.

I have my fingers crossed this time. If not a have ground wire that I am going to run separate grounds all the way up the frame to the engine block.

I’ll keep you guys up to date if this resolves my problem. Wish me luck!