12 October, 2024 | keystroke
My shitbox (a Mitsubishi Colt 2007) has a seemingly unique problem, at least not posted about online commonly: The headlight stick in some positions causes all the lights to flicker/turn off, usually when indicating right.
This started about 9 months ago when I noticed the right indicator buzzing sometimes when turning it on, but since I was busy I put it off as it was no big deal. It got worse, with the issue becoming more frequent before it started to occasionally dip my headlights. I assumed this was a fuse, relay or maybe alternator, but eventually this behaviour stopped and I thought it had self-corrected.
A few weeks ago it came back with a vengeance, cutting out all lights when the stick felt like it, which was incredibly dangerous on pitch-black country roads. With my car now trying to kill me I had no choice but to operate.
Due to the nature of the only systems affected being those on the same stick, my suspicions shifted to the stick itself maybe shorting or making bad contact when used. Thankfully the stick was easy enough to remove, just requiring the removal of 3 Philips-head screws under the steering column before levering the plastic around it off its clips, then just pinching the plastic tabs and pulling the stick unit out.
It appears to function fairly simply, with different pins shorting when the lever is in different positions. This was easily tested with a multimeter revealing the layout to be below (from left to right in the image and top to bottom in the car)
Part # 17D706
1 Ground
2 ?
3 ?
4 Low beam
5 Running lights
6 High beam (semi-pressed)
7 High beam
8 Indicate Right
9 Indicate Left
As the multimeter didn’t seem to reveal any unreliable contacts the next step was to try shorting out the matching pins in the car to see if it flickers with a probe shorting the contacts instead.
When measuring the matching socket on the steering column, all pins except 1 and 4 had a voltage of 0.5v and a resistance of 16Ω. I am still unsure what 2 and 3 do, however with a small wire I was able to activate the rest of the functions (sans the high beam as that requires the low beam to be on first and I only could short one at a time).
This confirmed that the flickering is either coming from inside the headlight stick unit, or perhaps the contacts between the unit and the socket in the steering column.
I wanted to have a go at pulling apart the stick before ordering a new one. If I was going to have to order one I might as well try to fix it.
Pulling it apart revealed a little PCB that the stick moved a contact around on to make contact with different pads in different positions. These pads corresponded to the pins above as I continuity tested all of them.
I found that the ground pad (left) could be inconsistent with the pin. If this was a bad contact that would explain why everything else on the stick would turn off, as they all rely on the same ground pin to short.
The soldering of the ground through-hole pin connecting the output to the pad seemed to be cracked, so I re-flowed the solder as well as adding a little bit more. For good measure I also cleaned the ground pad to check for damage (there was none) and cleaned the pins and contacts with isopropyl alcohol.
When putting it back together, I used some of the excess gel from the contact side to cover up the ground pad again. I assume it’s for lubrication but best to keep the status quo there. The rest of it went back together with a click and it appears to work again!
With that fixed now I can address the non-life-threatening issues that need to be addressed such as oil changes and spark plug health, but all of that would have been useless if this was a problem in the wiring harness I wouldn’t be able to fix.
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