Wiring Strange Turn Signal

[WannabeFree]

Need Help on my 84 CJ7 turn signal issue. For some strange reason when I turn on my signals on for both right and left rear lights flash but the front lights function normally . I know that most issues are do to poor grounds but I have double and triple checked all known grounds and everything checks out normal. I have recently replaced the turn signal switch and replaced both hazard and turn signal flashers. I do not have any LED lights. to recap my issue, The Head and tail lights function normal, Hazard lights function normal, Running lights front and and back function normal only my rear turn signals do not function normal as both blink at the same time right or left signal. I have checked all wiring and it all appears normal , no splices etc. So I am wondering if some how the new turn signal could be the problem even if the front lights work normal but not the rear. I have spend days chasing all wiring and such to no avail and could use some helpful suggestions.

 

[TSB8C]

For both left and right rear to blink together, two possible issues: (1) there may be a connection or short between the two. Has someone wired in a trailer plug where they may have connected it wrong? Otherwise, another wiring issue to trace out. (2) Bad ground, forcing the current to "backflow" through the other light. This would be evident by seeing if the lights blink but are not full brightness. Think of it this way: if the ground on one side is not making properly, the juice will still look for a way to reach a ground source. That ground source would be back through the blinker switch and through the bulb in the other light on the opposite side. So now each bulb would see half the full voltage (two bulbs in series at that point) and cause them to both light, but at half brightness.

So if half bright, grounding issue. If full brightness, wiring allowing both sides to be connected together somewhere.

 

[WannabeFree]

For both left and right rear to blink together, two possible issues: (1) there may be a connection or short between the two. Has someone wired in a trailer plug where they may have connected it wrong? Otherwise, another wiring issue to trace out. (2) Bad ground, forcing the current to "backflow" through the other light. This would be evident by seeing if the lights blink but are not full brightness. Think of it this way: if the ground on one side is not making properly, the juice will still look for a way to reach a ground source. That ground source would be back through the blinker switch and through the bulb in the other light on the opposite side. So now each bulb would see half the full voltage (two bulbs in series at that point) and cause them to both light, but at half brightness.

So if half bright, grounding issue. If full brightness, wiring allowing both sides to be connected together somewhere.

Your diagnosis is much the same as mine. It is difficult to determine if the light in the rear are half bright or not which would validate the grounding as the issue. However if I pull out the bulb in either tail light it does not eliminate one or the other from still blinking. My gut still says its some how a grounding issue and not a wiring issue but nothing makes sense when all other lights function properly. Is there some Ground under the dash or to the turn signal switch I am possibly not seeing or over looking. I also now am seeing a rapid flasher on both the hazards and the turn signals that just appeared while troubleshooting. I also do not understand how the back turn signals appear bonded but the front operate properly.
Thanks for all the suggestions and any new ideas., Dave

 

[TSB8C]

I agree, back to a grounding issue. Normally the front and rear lights are separated from each other electrically. But when you engage the turn signal switch in the column (move the lever up or down) that connects the front and rear turn signal lights on whichever side together with each other. So a ground issue in the front could affect the rear also. So start with the most common ground issues on CJs:

1. front turn signals in the grill. These lights have three connections, 2 are wires in the plugs and one is the light housing grounded through the mounting screws. A common mod, and one I always do, is to solder a ground wire to the back of the housing and then "hard-ground" that wire rather than simply rely on the screws into the sheet metal of the grill. A simple test would be to clip a test lead to the light housing and known good ground.

2. Not a ground, but common issue is the side marker lights up front. These get corroded contacts that are easy to clean and confirm. These lights act as only markers when you turn on the headlights, but become part of the blinker circuit when the turn signals are engaged.

3. The tail lights are grounded by a wire connected with a screw inside the rear quarter panel space. This gets rusty/corroded easily because the rear tires are throwing water/dirt up there as you drive.

4. The connector near the base of the steering column for the turn signal switch wiring. This is the long slender, usually black, connector for the wiring coming down the steering column and then connecting to the under dash harness. If you ever get rain or debris in the cab area, this connector can get stuff in it. Check the contacts here. You can see in this pic there are four separate wires coming out for the turn signals, 2 separate for the front (and dash indicators) and 2 separate for the rears. In addition, it is easy as a troubleshooting step to pop one of the connector pins out of the plug to then do a test and see if that makes only one light flash a time. That would confirm whether the turn signal switch in the column itself is the issue.

 

[WannabeFree]

OK, I think I will try de-pinning the turn signal switch wires one at a time that control the turn signals. Is there a trick to getting them out other than using a small pick or screw driver to try and release them. I have never done it so I don't want to damage the connector. This is a new switch I just installed but my 84 CJ7 wiring is slightly non standard as the turn signal flasher unit is not in the fuse block but instead hangs in a separate plug near the emergency brake. this confused me at first but I read that some CJ's in that year were wired that way. I am wondering if maybe the turn signal switch pin outs night be slightly differently for the turn signals and hazard light circuits ?. I doubt that is the problem but if I pull the pins and try using some temporary jumpers it might resolve that. I am also going to double check which filaments in the rear tail lights are actually flashing for the hazards and the turn signals which should give me some insight as to whether its still a ground/ back feed issue or not. I do not think it is a rear light grounding problem because I have checked it and I already added hard grounds to the front running light housings. I have not checked the marker lights ground because they seem to work fine but I will check them too.
I really appreciate the help and am determined to get it resolved . Hopefully this will help some others who might have similar issues in the future.
Thanks, Dave

 

[TSB8C]

I use a small pin (like for fabric) from my wife's sewing room to press the small "clip" and release the connector pins.