Hi All:

1986 XJ6 series 3 base

Today's mystery is a consequence of me trying to put in some LED dash panel lights. Why the bulbs are different for the left and right turn signal is beyond me, Anyway - I change the speedo light -- all good. I change the left turn signal light and all good. I change the tach bulb and the right turn signal and those two do not work. I change it back to bulbs - no go. Just the tach light and the right turn signal. Externally, both left and right signals work fine and sound normal. No other lights seem to be affected. As I'm writing this and thinking like an Englishman (or what I think an Englishman would think like). I didn't try putting all original bulbs back in. Any reason why a LED in the left turn signal would impact the other lights there? Ground wire? Not sure.

Any advice and counseling would be appreciated. Why did I mess with that? My wife noted the dash lights were pretty dark so I had the big idea of fixing that.

 

in my '84 Series 3, the left turn signal has a different bulb socket than the Tachometer turn signal bulb socket.

It must be that the Tachometer came from a Series 2 and the Series 3 came with an updated electronic Speedometer ?? Therefore the hybrid wiring harness.

the left Turn Signal wiring has a Diode in-line in its wiring about 2 inches back from the left Speedometer bulb socket which I replaced.

My symptom is that the Left Turn Signal bulb indicator stops flashing after two or three flashes, but the Tachometer bulb does not do it.




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When weird electrical problems occur an easy place to begin the journey is by checking grounds, yes.

The metal part of the dashboard has two ground tabs for the instruments and lights. One is next to the speedo and the other next to the tach. Make sure the ground wires are still attached.

Also, the harness for the instruments is actually 2 or 3 sub-harnesses linked together. Make sure none of the connections came apart.

Cheers
DD

 

Thanks Doug -- very helpful. I was looking for the ground wires (briefly) and didn't see anything clearly. Are they just black wires attached to a screw?

Do you remember what they are coming off of? Is it a wire off the harness? Thanks so much for the assistance in this. Electrical issues like this scare me because the rabbit holes I've gone done have been deep and frustrating.

 

Black wires and just push-on connectors

If you're sitting behind the wheel looking at the dash the ground tabs will be next to the tachometer at about the 8:00 o'clock position and next to the speedometer at about the 4:00 o'clock position. the tach and speedo will likely have to be removed to see them

Cheers
DD

 

Thanks to Doug, my tach and other left sided gauges are lit. Only the right turn signal isn't lighting up, which means the problem is wire to, housing or bulb to that area.

It's so hard to never take a right turn in San Francisco.

 

All good now?

 

in my 1984 XJ6, I did the flashing side markers mod and I thought that was the reason for the Left turn signal indicator flashing two or three times and then shutting off.
** note last comment.

So I put everything back like it came from the factory, (static, non-flashing side markers).
But no change, same issue.

Then Doug told me about the Diode in the wire harness, and I went through replacing it, but no change, same issue.

Then I suspected and replaced the flasher relay (twice), but no change, same issue.

So what is the cause ?

It only happens to the Left Turn Signal indicator and only at the gauge, since the exterior lights continue to flash normally, with or without the flashing side markers mod.

** I notice a voltage drop at the indicator bulb just before it stops blinking, so this drop of voltage can only come from the flasher relay, no ?

 

To complete this -- bulb was bad on the right.
Dash works except for a missing bulb and housing for the "brights" indicator on the center piece. I'll consider it a win