Front Right Indicator Light Gremlin

PunjabRover

PunjabRover

Member
Hi All -

I've been working on a gremlin with my right front indicator and looking for any guidance / suggestions on how to resolve (1991 D110 200 TDI). I'm not super savvy on the electrical side, so bear with me as I am learning and fixing along the way.

Problem
A few months ago, both indicators on the right front side stopped working (forward facing and side marker). When I indicated to the right or put on my hazards, those two lights would not turn on.

First Resolution
I did find that the ground wire from the forward facing bulb was not secured to earth properly. I ran a new ground wire from wiring harness near the front facing light to the bulkhead and secured it to an earth point on the bulkhead. Surprisingly, the side marker light now works, but the front facing light continues to not work. However, if I remove the bulb from the front facing light, then the side marker light does not work. Seems like the current for the side marker light is flowing to earth via the front facing light.

What I've tried
  • I swapped the bulbs (left to right), no change
  • I swapped the light wiring harness (left to right), no change, but the RH wiring harness does work correctly when connected to the left side
  • I got a new Flasher Relay (PRC8876), no change
  • I checked the voltage on the black wire for the front facing light and when the hazards are on, it cycles between ~10-11 volts and 0 volts (this feels like it should be right since its supposed to be flashing).

Some videos for reference

Any thoughts on what to check next? I've generally lived with this for a few months, but I do need go in for inspection in the coming weeks, so looking to try to resolve. Appreciate any input and happy to take more pics / videos.
 
erover82

erover82

Well-known member
See if you have any current (Amps) flowing through the front indicator bulb. Leave the bulb in place when you insert the multimeter between the bulb holder and the harness. It's possible there's enough current flowing through it to light the side indicator, but not the front. This would indicate the side repeater is finding ground through the front bulb as you alluded to. This would subsequently point to an issue with the harnesses' grounding points. You'll want to inspect every one and remove any corrosion. I like using Ox-Gard which is a conductive compound that aids conductivity and prevents corrosion.
 
PunjabRover

PunjabRover

Member
Thanks. Here are a few more videos showing the volts (millivolts) and the amps between the good side (left) and bad side (right) flowing to the front facing indicator bulb.

Good side:
  • Fluctuates between 12-14 mV and 5 mV
  • Fluctuates between 4-5 amps and <1 amp


Bad side:
  • Fluctuates between 130-150 mV and 60-80 mV
  • No real amp detection



Based on your guidance, I'll further inspect the grounds and make sure the front facing bulb is getting to ground appropriately. I did also just put in an order for a Hazard switch, just in case that is it. I head read elsewhere that everything flows through that switch and can be a common fault.
 
evilfij

evilfij

Well-known member
Turn the hazard switch on and off a few dozen times. That often fixes them. If you have contact cleaner, spray that in there I suppose (never done that with an hazard but will next time). Also, I always replace the fuse even if it tests good and looks good. I fixed a heater blower issue with a new fuse in that circumstance.
 
M

Mirrajumper

Well-known member
I haven’t ever seen a defender that didn’t benefit from new bulb holder sockets and quality bulbs. The tab is under tension when the bulb is inserted to ensure contact. They get “flat” and intermittent with age. Cheap insurance before going on a witch hunt.
 
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