Tail lights and signals going whacko.

[mike's1965]

All 3 harnesses came today from Classic Parts, from Kansas City, MO.

The brand on all 3 is American Autowire.

Also the front harness that connects to firewall, then to rear harness has a backup light harness already built in, the rear harness might too but not sure yet.

No plans on backup lights, but it's nice it's included.

Hope it fixes the issues.

[0ldSoul]

Originally Posted by mike's1965

All 3 harnesses came today from Classic Parts, from Kansas City, MO.

The brand on all 3 is American Autowire.

Also the front harness that connects to firewall, then to rear harness has a backup light harness already built in, the rear harness might too but not sure yet.

No plans on backup lights, but it's nice it's included.

Hope it fixes the issues.

Get to work!

[lowroder]

Originally Posted by mike's1965

All 3 harnesses came today from Classic Parts, from Kansas City, MO.

The brand on all 3 is American Autowire.

Also the front harness that connects to firewall, then to rear harness has a backup light harness already built in, the rear harness might too but not sure yet.

No plans on backup lights, but it's nice it's included.

Hope it fixes the issues.

Mine Also included the extra wire ...According to american autowire the extra wire is licence plate light . I asked the tech when trying to trouble shoot my faulty harness i got

[mike's1965]

Got it all replaced and did add grounds, all working good now.

On mine there is the extra wire for backup lights, there is another lead for license plate light.

The blinker speed does seem faster than modern cars, bought a new flasher but did not install yet.

Looking back seems the blinker was always faster.

[tigerburns]

I am dealing with a similar issue. I have a 65 with the original fuse box, and some new wiring here and there. When the truck is on the taillights flash like hazard lights; but the passenger side is much brighter than the driver side. If the lights are turned on, the taillights still flash, but seemingly independent of one another, i.e. at a different frequency.

Push the brake pedal and brake lights come on with no flashing. Turn signals make the light on the side of the turn flash brighter, but the other still blinks.

When I read this thread I thought this sounded like my problem may be ground, so I added a ground wire from the tail light housing clips to the frame rail for both lights. I also checked all fuses and cleaned the connectors where the rear harness plugs into the connector at the frame. Same issues.

Any suggestions? Lights worked fine until driving it this past Friday. Do you think I should replace the rear wiring harness completely? Electrical problems are confusing...

[mike's1965]

Are you 100% sure the grounds you hooked up are good grounds?

If you don't have one, get a test light, bought mine late one night at Walmart last year troubleshooting radiator fan electrical on PT Cruiser, before that always used multimeters since using them for HVAC work.

Anyways I used test light again to test for power and grounds.

If you get test light to light up from power source in socket, tail light, or flash of blinker to your ground( or brake light if you have a helper), then you know your ground source is good.

Seeing the test light blink on and off with the signal turned on while trouble shooting was cool, I'm used to just seeing voltage on readout.

Also double check the ground connections and connections on your tail light sheet metal is scraped clean with a wire brush or whatever.

I noticed on my old harness while trouble shooting, after pulling harness out and putting back in, the 2 nubs (electrodes the bulb touches) inside the bulb housing had gotten crooked, it was pointing off at an angle, not straight.

New harness did not have this, old harness was just hacked to hell, maybe the socket for bulb was loose from over the years, it would keep going off at angle and not line up straight in driver's side.

Do you have negative battery cable grounded to engine block, and ground from same connection at block going to frame with a ground strap/cable?

If you already have verified ground with test light, then disregard, probably time for new harness.

My old harnesses are so stiff/brittle compared to the new harnesses.

No regrets replacing all 3 lighting harnesses.

[mike's1965]

I forgot to tell in detail about how I added grounds, only added ground on tail lights.

Took out each tail light sheet metal one at a time, disconnect harness take out bulb, layed face down on my trash can as a work bench (the kind with wheels you roll out to street and gets lifted up by trash truck) haha.

Laying face down, used a drill and self tapping sheet metal screw below where bulb goes in on flat area, away from mounting holes, just enough to get threads started then back out screw.

Wire brushed area over hole for good connection.

Crimped on a wire connection that has what looks like a washer, one that fits best for self tapping screw, then mounted that with screw, the screw goes inside housing below bulb, did this on both sides.

Ran ground wire down with tail light wires, added same connection on other ends after getting lengths just right, hooked them onto license plate light, the one on my truck has 2 lights, put connection in between bulb housing and license plate frame.

Sorry didn't get any pics of this, I'm sure there are better ways to make grounds, this works for my truck.

I tried adding grounds to front for trouble shooting, but found out it was bad wiring harness, and everything works good after new harness.

[tigerburns]

The ground wires I made from 16 ga copper stranded wire. I added an eyelet connector to both ends with a soldered connection. I crimped the base of the eyelet and added heat shrink wrap over that to keep moisture out.

On the frame side, I connected both wires to an open hole in the frame that I wire brushed and wiped clean, then connected with a short bolt and nut.

Each tail light bucket was removed and wire brushed on the back side (opposite of the bulb). When I put the buckets back into the truck, I connected the bulb wires and connected the ground eyelet to the top screw that connects the buckets to the truck. The bulbs, I replaced as a part of this work, and I ensured both lined up with the harness contacts.

All connectors and connections were wire brushed, so I thought them to be cleaned.

Yes on both the battery negative being grounded to engine block and block grounded to the frame at the same location.

Maybe I need to take your suggestion and get a light tester. I will have to order from amazon bc I don't go to Walmart...haha.

In the meantime, I will try to recheck all of my connections again. I wonder, do you think adding a dab of bulb grease to the connections would help?

I am also going to trace the wires all the way back to the firewall and make sure I don't have any crimps or bare spots creating a short. I may also check the contacts on the harness where it contacts the bulb. Those could probably stand to be cleaned anyway.

[mike's1965]

Get the test light to know for sure.

I didn't use any bulb grease, but it probably couldn't hurt.

[BOE]

i would buy autowire basic kit for entire truck. suppose to be easy installation.

[tigerburns]

Update from work last night...

I went back through, checked all of my connections on the ground wires, and found that the clips the light housing screws to had some body paint on them. I removed the clips and wire brushed all the paint off, and cleaned inside the clip itself with sandpaper.

While the housings were out, I also wire brushed the holes where the screws go through until the metal was shiny. I then went back to the frame connection and wire brushed and cleaned until that metal was shiny. There is now no rust or paint at any of the connection points.

I screwed everything back in, plugged it up, and Viola!...still flashing!...Ugghh.

I am going to get the circuit tester today and see what it tells me. I still need to trace the rear harness back to the firewall to see if there are any breaks along that. After that, my next step is to spend some money, I guess. I will have to break down a buy a new rear harness.

Stay tuned...

[cwcarpenter98]

Hey tigerburns, did you check your turn signal switch? A faulty turn signal switch can do some funky things to the rear lights

[tigerburns]

Originally Posted by cwcarpenter98

Hey tigerburns, did you check your turn signal switch? A faulty turn signal switch can do some funky things to the rear lights

I have not. You are talking about behind the steering wheel right? How can I tell if that switch is bad?

[mike's1965]

When I used the test light, was focused on front lights and that's when I pulled the front harness connection off the plug on the firewall, would go turn on left signal and probe the 3 terminals in the plug.

Other end of test light was hooked to negative battery cable with some jumper wires(not jumper cables, set of small wires with alligator clips on each side) to give more length.

Doing this showed me that each turn signal worked by itself, also that parking lights were working, plug harness back in and no signal near the bulb.

Seems you should be able to do this by pulling the rear harness connection from the firewall, the inside harness plug will pull through with it and give you a couple of inches of slack, having a big block in my truck this made it extra hard to separate the 2 connections, they were stuck together really good after so many years.

I fought with them for probably 15 minutes trying to be gentle to the inside harness plug as it's plastic, if it breaks not even sure there is a replacement.

Ended up pushing them back like they were on firewall, went inside and under dash, used my small set of channel lock type pliers pulled hard and got the 2 plugs separated.

The outside part of plug was too big to get pulled through the firewall hole.

You then could try testing the connections at the inside harness one at a time, just need a good ground for the test light, if you buy a really nice test light it may have longer leads, if the ground lead is too short, use jumper wires and connect as many as you need to get back to negative at battery, or another ground.

So turn on say your left turn signal, try all terminals, only one should make test light blink, then try right signal, only one terminal should work for that side.

That would be my way of testing.

[cwcarpenter98]

Originally Posted by tigerburns

I have not. You are talking about behind the steering wheel right? How can I tell if that switch is bad?

The turn signal switch is inside the column. Have to pull the steering wheel to gain access to it. My original switch is still good, so I haven't had a need to test it. I'm not sure how to tell if it is bad, I have just read mentions of turn signal switches doing funky things to the brake lights

[tigerburns]

Finally resolution!!

Just an update to close out the thread...

So I checked my grounds and my connections with a circuit tester and found them to be good. I decided the problem was either in the rear wiring harness or the turn signal switch. As it turns out, it was both.

I got a new rear harness and turn signal switch from Eckler's (super fast delivery to my part of the country BTW). When I installed the rear harness, the lights were still blinking, however, they were now the same brightness. Previous, the driver side bulb had been much dimmer than the other side. I then installed the new turn signal switch (which also has a wiring harness attached). My original under-dash wiring was gathered together in a couple spots with zip ties. I noticed when I cut the zip ties that a dark blue wire (right turn signal) had a bare spot; which turns out, was creating the short. I put some wire insulation and electrical tape over the bare wire, hooked everything back up and Voila!! It all works as it should!

Whew!! Electrical gremlins are tough adversaries.
Plan is to eventually replace the complete wiring harness and fuse box for the truck to a more updated version. 50+ year old wiring can't be trusted.

Thanks for everyone's help on this board and thread.