Good Day,

Prior to pulling the column covers and cluster I figured I'd ask and see if anyone has had a similar issue which may help narrow the amount of items to check. I'm currently facing two issues, they may be related or they may be two separate issues, likely culprit is a bad ground or switch.

Issue #1: When driving, when I hit my right turn signal, I lose all my interior lighting, except for the green turn signal indicator, and the odometer LCD. all the gauges work correctly and the car doesn't display any other issues other than this rather peculiar electrical gremlin. Left turn signal works fine. Exterior lights all work fine.

Issue #2: The other day, my tachometer started to behave erratically and then suddenly died. No other issues with vehicle. I've searched the many common tach related issues on the forum (consensus seems to be bad ground/connector behind the tach, or a failed capacitor on the tach itself).If anyone has had issue #1 before I would be curious to know what your diagnosis is. Given that they are both electrical, the possibility that a single bad ground is affecting both items can't be ruled out at this time.

Car is a '93 LHD, no mods, original harness. Ran beautifully until these issues cropped up (still runs great infact), there's a bit of a rough idle as the car works through its cold start (popping from the exhaust between 1000-1500RPM until warm) but I don't think that this would be related to the items above (could be any number of small vacuum or exhaust leaks that these cars develop).

Your thoughts are appreciated.

Cheers!

 

Hey Dead Eye,

First, I'd pull the under panel beneath the steering column (the one with the vent blower, not the steering clock cover) and the drivers side outer kick panel to get access to the wiring connectors and fuse box (this may be on the passenger side as I have a RH drive).

The Dash connector should be a green plug that connects directly into the fuse panel, check if it's slightly loose or for any damaged cables. The same for the blue connectors attached to the white plastic holder underneath the steering column.

I'd also recommend to download the (Z)Wiring Diagram service manual and take a look at page Z-62 to trace the indicator wires (Right Indicator switch looks to be a Solid Yellow Wire).

 

First off, for interior lights you are saying the dash lights - all the gauge lighting, the illumination on the HVAC panel, etc. Correct? I assume this isn't noticeable during the day with headlights off?

When you cancel the turn signal do the lights come back on?

Do you have ANY aftermarket electronics - stereo, turbo timer, anything?

The tach thing is probably just the tach itself, though I would sort out the turn signal issue first them see how the tach does.

Dale

 

Dale, yes when I cancel the turn signals everything goes back to normal. Car is factory down to the Bose stereo. Gauge lights as well as the lights on the HVAC/console that would normally light up - never noticed it during the day as the lights are off but I would assume such (I'll check it next time I'm in the garage but would expect this to take place).

Thanks guys.

 

Do they stay totally off or do they blink on and off in time with the turn signal?

The CPU#2 in the driver kick panel, I would pull it out and unplug the flasher relay, that's the plug at the very bottom. See if it does the same thing with that relay unplugged.

May also be worth checking both fender liners to make sure you don't have your tires rubbing through the liner and into the harness. That's the source of MANY weird electrical gremlins.

Dale

 

Dale, the interior lights stay totally off - very binary response from the lights, with the indicator lights on, the interior lights are hard off (except for the green indicator light on the cluster), the interior lights return as soon as the indicators are turned off.

Fender liners are intact without rubbing.
Will add the Flasher relay to the list to check, thanks.

 

With the interior lights out, do the exterior running lights turn off too?

That is SO weird.

Dale

 

Gets even weirder, I just went to check out what you mentioned above and I can add the following:
1) The exterior running lights turn off as well (headlights, turn signals, brake lights, high beams, etc. all work as normal).
2) The indicator issue does not manifest itself unless the right indicator is LOCKED on, so if I just lightly turn the indicator on as one would during a lane change, nothing happens, but when you lock the indicator on as you would waiting to turn right for example, only then do the dash and running lights turn on.

To me the latest findings above may point to a bad switch in the indicator stalk assembly or maybe a pinched wire somewhere up there? Or my car is haunted.

 

Mice?

What happens when you turn on the emergency flashers? Same as the R turn signal?

 

Mice: I hope not, doesn't appear to be anything chewed up anywhere in the car or the engine bay. I'll put extra traps out this winter though.

Emergency flashers: operating as per normal, both with the RH indicator on/off. Whatever the problem seems to be seems to be contained exclusively to the circuit that affects both the RH indicator and the running lights/interior lights, and only when the RH stalk is locked on.

 

I'm wondering if a wire is getting pinched in the steering column or something. That is strange.

The dash lights and outside running lights are all the same circuit, so that makes sense.

Dale

 

Agreed, either that or a failing combination switch - both the running lights and indicator stalks are on the same combi switch.

 

I recently posted up about the Body Electrical Manual, that may have some troubleshooting procedures for the combination switch.

Dale