Taillight issues

[FSJfan]

When ever the lights are on the passenger side tail light is dim. There are new bulbs in it. When the lights are on and put the turn signal to the left it goes super fast when it goes to the right it goes super slow then sometimes speeds up to normal. Also when the lights are on and the turn signal to the left is on the passenger side tail light goes out. I have checked the grounds for the taillight housing it all checks out. What could be the issue?

[twisted frame]

My first thoughts are try are:
- Resistance is too high on passenger side circuit. I can't remember if this goes through the floor-mount dimmer switch but when my dimmer switch went bad it screwed up all kinds of electrical stuff.
- Is the flasher at the fuse block good?

[tgreese]

Recall that the front indicators and side markers are in the blinker circuit, along with the tail lights. I would first check that grounds for everything are good. To me, this means removing the attachment to the body or frame, and re-seating the connection with a new toothed washer and a little dielectric grease. Use contact cleaner on the sockets, connectors, bulb bases and ground connections. Deoxit is best, but expensive. I'd also check all the sockets and connectors between the dash and all of the lights. Make sure there is no corrosion in the sockets. Again, a little dielectric grease is good on the bulb bases.

As pointed out above, the flasher unit on the fuse block can wear out. If the load is a little different left to right (due to corroded connections typically), the flasher relay may fail on one side and not the other. Check that the emergency flashers work. In most cases you can swap the two flashers relays and see if one or the other is weak.

Finally, the indicator current goes through the turn signal switch in the column, and these can fail. But thoroughly check all the connections first, since replacing the column switch requires taking apart the column. A bad connection is much more likely than a bad switch.

[csuengr]

Grounds, grounds, grounds.

Don't now about J-trucks, but on my Cherokee (1977) the bulbs on the rear lights are grounded through the housing. I had to do a little scraping on the housings where the bulbs contact to get my lights to work.

[tgreese]

Yep. Looking at the wiring diagram, I see that there is a front lighting ground connection on the core support that serves the indicators and side markers. The rear indicators appear to ground through the housing to the bed - make sure the connection between the housing and the bed steel and the frame is good. The ground has to go all the way back to the battery to be a circuit. Steel body cars use the body and frame as one big ground buss, though steel is not a very good material for this. Strong, but corrodes readily.

Likely you won't find a single cause for this, but you'll clean and tighten a bunch of connections and suddenly it will work right.

[tgreese]

... a little scraping on the housings where the bulbs contact to get my lights to work.

Deoxit is great for that - https://www.amazon.com/DeOxit-Cleaning- ... oxit&psc=1

"Technician in a can." Also works great on scratchy pots in your guitar amp.