stealth

86.5 RR side marker not working. 9V measured at the wire ends (new quick-disconnect crimped onto positive lead to replace patina-laden original one, same result). Bulb was good (as confirmed in front parking light) but rather rotted and broke when I was trying to remove it a 2nd time, replaced with new (could only get the long life type).

Is my next step to pull the bumper cover and check out the taillight assembly harness? All other lights on the car are working. I just did a fuse refresh last weekend.

the flyin' scotsman

check the ground wire; its common to many of the rear lights.

Alan

It is very likely to be a grounding problem. Reinstall the bulb and measure the ground at the bulb to a clean ground point - what voltage - measure the voltage from the bulb positive to the battery positive what voltage?

This will tell you if the voltage drop (due to corrosion/poor connection) is in the power wire or the ground wire...

Alan

stealth

14-hour workdays lately, just getting some shark time again (should be getting sleep...)

With multimeter positive lead on the marker light positive wire, voltage 10.5 vs the ground point near the hatch release and -1V to the battery. With key off/lights off, -12V vs battery, as it should be. With the positive multimeter lead on the bulb ground, 11.5V vs ground (hmmm) and approximately -1V vs. positive terminal (voltage drop due to resistance in wire?). These measurements imply both a short and an open (no voltage drop across bulb, but current not reaching ground)?!? (Maybe I should try sleep instead of shark?)

Mrmerlin

Hey Shane if your working on the rear side marker lights look along the rearcorners of the hatch floor for a white connectors this is for the side marker they usually get wet and corrode fix this first then your lights should work, Stan

If you dont see the connectors along the floor then you may have to peel back the rear edges of the inner quarter liners, be careful as the fiber board will crack if its bent too much. The white connector will be behind this cover if its not along the floor

stealth

I think you'd be right if it were my GT with the problem but I think on the OB the markers are wired to the tail light assembly and that's the one with the issue .

Landseer

I think that you really need to remove the passenger quarter panel, else bend it back, as Stan suggests.


There is a harness ground point behind it. Plus the various connectors. Removing the bumper cover is unlikely to give you access. Plus, there might not be enough wire slack between the white connector which is behind the panel and the tail light assembly to allow removal of the bumper cover / tail light assembly anyway without cutting the wires.

Do you have a right rear tail light burning, just not the marker? If so, I think the fault can immediately be isolated to the short jumper harness that sucks power off the tail circuit to power the side marker.

Or is the right tail out also, which has other implications?

Does this make sense? I've spent a whole lot of time sorting the wires on an 84 and that is what I found. 86 diagrams on this aspect are showing same connectivity as 84.

Mrmerlin

The white connector is on the inside of the car body along with the rear tail light harness connector, you will find it inside the rear quarter liner also as suggected check the ground wire thats near this harness

stealth

Yes, taillight works. I thought the harness was a bus connector ON the taillight, though, Easier to look behind quarter first, so I'll take a look. Because the tail light worked, I've been assuming it was the short harness since the start, but I thought only the 87+ had the connection inside the vehicle.

KY928

Check the relay!! I had same prob. with RF turn signal, after checking grounds, chasing wires, voltages, etc., it was the relay...

stealth

This must an 86.5 "enhancement". I do have the white connector with gr/br wires (86 wiring diagram shows it connected to the taillight, 87 diagram shows this separate connection). Someone has been in there before, the cardboard was already broken.

Unplugged the connector, checked voltage...plugged it back in and the light came on!

Thanks for pointing me at that connector, I thought it was not there on OB, but I guess it is on 86.5!

Now I have to get under this thing and fix an exhaust leak at the X-pipe and it'll be ready for inspection and road use again.

Alan

But ... There is no relay ...!

It sounds like its probably just a ground problem as we said initially...

Alan