1990 turn and parking light issue left front and dash

[Black1990jeep]

This is for a 1990 XJ...

SYMPTOMS....
problem. when headlamp is turned on or parking light is turned on via the dash pull switch, the LEFT hand green dash signal arrow illuminates. This green signal arrow does not illuminate however IF I remove BOTH front left signal bulbs when I turn on the headlamp or parking lamp The two left front signal bulbs do not turn on not even a faint glow when this green left arrow on dash is on like this.

In addition to above, the front turn signal are supposed to alternate from side signal to front signal when turn is commanded if headlamp or parking lamp is on, and when no headlamp or parking lamp is on, then both these front signal are supposed to flash together. This is what occurs on the RIGHT side , but not on the LEFT side. On LEFT side the two front left bulbs flash together, but do so dimly, it does not matter if headlamp or parking lamp is on or off, they two front left bulbs dimly flash together.
When the green arrow on the dash is on steady when headlamps or parking lights are on, it does go into flashing mode when LEFT signal is commanded, and but stays on solid when RIGHT signal is commanded. When headlights or parking lights are off the left green signal arrow is off if no turn signal is commanded.

When parking or head lamp is on I get no parking light on left front, it stays off.

The LEFT hand turn signal does flash a bit slower than the RIGHT signal

Hazard lights work, BUT the LEFT front hazard blink very dim compared to the RIGHT side. BOTH LEFT and RIGHT rear hazards are same brightness.

Tail lamps and tail signal lamps work correctly.


I have cleaned the bulb sockets, and refreshed the ground on the left inner fender, plus checked it for voltage drop to battery ground and it is just a few millivolts drop. So that is good. I also cleaned the front lamp connector that is located ahead of the air cleaner, behind left headlamp.
I swapped the two flash cans (turn and hazard), with no change in symptoms, I bought a brand new flash can and installed in turn can socket, no change in symptoms.

I am really stumped here. I still dont quite understand how the front a front side signals are suppose to work, i.e. how they are supposed to flash together when headlamp or parking lamp are off, but alternate with head lamp or parking lamp are on. Perhaps If I understood that I might be able to find the fault?

 

[Rob Mayercik]

I think it might be time to look at the headlight switch itself, since you indicate "normal" operation of the blinkers depends on whether running lights are on or off and you have no LF marker light right now.

Once you get this resolved, I think it's also time to think about picking up one of those plug-and-play relay harnesses so the bulk of the headlight power is no longer going through the headlight switch.

 

[tjmotter]

are any of your bulbs LED? As strange as this might sound, LED lights work radically differently than incandescent bulbs and can cause issues. For example, I replaced all my bulbs with LED on my '90xj and suddenly found that the cruise control wouldn't work. Turns out, the cruise controller wire that monitors the brake light circuit expects to see a ground through the bulb when the light is off. Normally this would be the case but with LED's, the ground is isolated so the cruise couldn't work. I added a relay to correct this behavior and all is perfect again.


I haven't looked into how that blinker circuit works but like you, I have noticed that the on/off pulse is opposite for the front and side markers. I haven't bothered to look into how this is wired to figure out why but it is not outside the realm of possibility that an LED bulb could affect this behavior.


First, I would confirm that you don't have LED. If you do, try spinning the the bulbs into the opposite orientation and test. If that doesn't work, try incandescent bulbs.
​

 

[tjmotter]

To add to this, NOTHING I have seen in my 1990XJ is digital. Every circuit I have worked on or repaired is an analog circuit. Analog circuits work very differently than digital circuits and expect specific conditions to be present. If they are not (like perhaps, not being able to detect a ground through a bulb), weird things happen.


I work in computer design and spend a lot of my time with a multi-meter in my hand so I have a pretty firm grasp on most things electrical....

 

[lawsoncl]

Poor ground at the headlights or turn signal?

 

[Ol Blue]

Did you or anyone do a H4 Headlight upgrade?

I had a very similar issue to what you describe when I got my XJ. Previous owner had done the H4 upgrade and butchered it. He tried replacing the flasher relay and turn signal switch but failed to fix it. Ended up being a bad ground. Not sure if the kit was messed up or he just messed up installation. But I soldered in a jumper ground wire to the ground coming out of the headlight on each side and it has worked great ever since. Seems like bad grounds are usually the culprit with weird symptoms like this.

 

[four_shot]

Just to get it out there, make sure the bulbs are correct and not internally shorted. An 1156 jammed into an 1157 socket can cause this type of failure. Similarly, if the bulb is shorted internally, it will cause the same thing.

 

[Black1990jeep]

SOLVED!!!!!
Turns out the ground contact in the socket has failed, internal failure in the socket, not made to disassemble for repair corrosion got in there, likely from the back side as the rubber boots they use are not really water proof. ORielly Auto Parts sells the Dorman #85898 The package states it is for a 1974 thru 1989 Ford, but it is an exact match to the Cherrokee socket 13 bucks.
I slathered dielectric grease under the rear wire boots to prevent corrosion from reoccurring. The water even corroded the ground wire of the harness back under its insulation back behind the socket where I had to make the splice, the copper strands were black, so I had to clean the strands up with fine steel wool and electric contact cleaner spray before soldering on the new socket pigtails.

 

[Black1990jeep]

PS the socket ground contact looked fine, it failed deep in the socket where wire contacts the contact, not visible.

 

[jeep ride]

Glad you got it figured out thanks for the update.

 

[four_shot]

Well done!

 

[Rob Mayercik]

SOLVED!!!!!
Turns out the ground contact in the socket has failed, internal failure in the socket, not made to disassemble for repair corrosion got in there, likely from the back side as the rubber boots they use are not really water proof. ORielly Auto Parts sells the Dorman #85898 The package states it is for a 1974 thru 1989 Ford, but it is an exact match to the Cherrokee socket 13 bucks.
I slathered dielectric grease under the rear wire boots to prevent corrosion from reoccurring. The water even corroded the ground wire of the harness back under its insulation back behind the socket where I had to make the splice, the copper strands were black, so I had to clean the strands up with fine steel wool and electric contact cleaner spray before soldering on the new socket pigtails.

Glad to hear you got it fixed. Not surprised about the socket being listed as a Ford part, considering Jeep (at least prior to Chrysler) never designed anything if they could= buy it from someone else...

 

[RCP Phx]

All vehicles that use sealed beams/H4 lamps have the same connectors!!!

 

[RCP Phx]

Sorry, wrong thread! A