pass side tail light and flasher out.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 170
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pass side tail light and flasher out.
I’m having a strange issue with the pass side tail light. The brake light works but none of the others do. The car is a 1986.5 I’ve checked the connector that’s behind the hatch cover and it’s clean. The bulbs are good. The fuse is fine also. I’m out of ideas… 
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
I'm thinking ground. Either behind right quarter panel or within the tail fixture as several different lights share same ground that link together on approach to that quarter panel ground point.
Focusing just on taillight, as if flasher wasn't an issue...
Left side of car works, right doesn't?
Unplug the right round connector.
With lights on, there should be 12V on terminal #4 (has grey/redstriped wire)
(measure from the car-side of that connector to a known good ground, ie bat cable)
If you have 12V there, problem might be bad ground.
Main ground for these various light fixtures is located near the connector, but buried behind the quarter panel. Could also be corrosion within light fixtures. Marker and tail should work together on each side, BTW. Assuming you don't have right rear marker either?
Right side fuse is 41. Covers front right marker, rear right marker and rear right tail. 5 amp.
With light switch on, you can backprobe CE panel plug S23 with a voltmeter, other end on known-good ground. Should have 12V.
If 12v at CE S23, but not at right rear connector, suspect bulb comparator unit. All power for tails and stoplights passes through that little box hidden at the right side of passenger package tray.
Flasher is separate and doesn't pass through the bulb comparator, btw.
With right Flasher on, unplug that same round connector near taillight. Terminal 1 should show 12V on/off/etc as the relay cycles.
Wire color is black with green stripe on passenger side rear.
Focusing just on taillight, as if flasher wasn't an issue...
Left side of car works, right doesn't?
Unplug the right round connector.
With lights on, there should be 12V on terminal #4 (has grey/redstriped wire)
(measure from the car-side of that connector to a known good ground, ie bat cable)
If you have 12V there, problem might be bad ground.
Main ground for these various light fixtures is located near the connector, but buried behind the quarter panel. Could also be corrosion within light fixtures. Marker and tail should work together on each side, BTW. Assuming you don't have right rear marker either?
Right side fuse is 41. Covers front right marker, rear right marker and rear right tail. 5 amp.
With light switch on, you can backprobe CE panel plug S23 with a voltmeter, other end on known-good ground. Should have 12V.
If 12v at CE S23, but not at right rear connector, suspect bulb comparator unit. All power for tails and stoplights passes through that little box hidden at the right side of passenger package tray.
Flasher is separate and doesn't pass through the bulb comparator, btw.
With right Flasher on, unplug that same round connector near taillight. Terminal 1 should show 12V on/off/etc as the relay cycles.
Wire color is black with green stripe on passenger side rear.
Last edited by Landseer; Jan 16, 2011 at 11:45 PM.
Rennlist Member
Joined: Oct 2010
Posts: 78
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From: Tampa, Fl
On my 86.5 i am having a very similar problem, except its my passanger brake light. Bulb is brand new and it will come on very seldomly and then its out again. So its almost always out. The light on the dash also signals that its not working.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 170
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Thanks, Landseer! I'll check that out when I get in tonight.
Yes, all markers are out on pass side but working on driver side. I do have the running lights working properly though.
One question: what is S23?
Yes, all markers are out on pass side but working on driver side. I do have the running lights working properly though.
One question: what is S23?
Team Owner
Joined: May 2004
Posts: 31,296
Likes: 4,269
From: Philly PA
S 23 is connector S ,
second row,
and 3 from the bottom ,
looking at the plug installed on the CE panel.
Before you go tracing for power,
first replace all of the side marker bulbs with the same size, and inspect each connector .
If you have a 3rd brake light also replace this bulb.
and replace all of the rear bulbs with matching sets side to side do the fronts as well,
Note you can use your old bulbs for spares.
I suggest to use a dab of dilectric grease on all of the bulb ends to prevent future corrosion.
Clean the ground connection point behind the rear quarter liner its easier if you remove the rear cargo hold down first so you dont damage the liner.
Also remove the connector for the bulb control unit on the edge of the passenger side parcel tray see if its corroded,
inspect the grounds under the hood along the front pan and sides for corrosion
And as always what was the last thing that you fixed??
second row,
and 3 from the bottom ,
looking at the plug installed on the CE panel.
Before you go tracing for power,
first replace all of the side marker bulbs with the same size, and inspect each connector .
If you have a 3rd brake light also replace this bulb.
and replace all of the rear bulbs with matching sets side to side do the fronts as well,
Note you can use your old bulbs for spares.
I suggest to use a dab of dilectric grease on all of the bulb ends to prevent future corrosion.
Clean the ground connection point behind the rear quarter liner its easier if you remove the rear cargo hold down first so you dont damage the liner.
Also remove the connector for the bulb control unit on the edge of the passenger side parcel tray see if its corroded,
inspect the grounds under the hood along the front pan and sides for corrosion
And as always what was the last thing that you fixed??
Drifting
Joined: Jul 2009
Posts: 2,582
Likes: 286
From: Gibsonia, PA
S 23 is connector S ,
second row,
and 3 from the bottom ,
looking at the plug installed on the CE panel.
Before you go tracing for power,
first replace all of the side marker bulbs with the same size, and inspect each connector .
If you have a 3rd brake light also replace this bulb.
and replace all of the rear bulbs with matching sets side to side do the fronts as well,
Note you can use your old bulbs for spares.
I suggest to use a dab of dilectric grease on all of the bulb ends to prevent future corrosion.
Clean the ground connection point behind the rear quarter liner its easier if you remove the rear cargo hold down first so you dont damage the liner.
Also remove the connector for the bulb control unit on the edge of the passenger side parcel tray see if its corroded,
inspect the grounds under the hood along the front pan and sides for corrosion
And as always what was the last thing that you fixed??
second row,
and 3 from the bottom ,
looking at the plug installed on the CE panel.
Before you go tracing for power,
first replace all of the side marker bulbs with the same size, and inspect each connector .
If you have a 3rd brake light also replace this bulb.
and replace all of the rear bulbs with matching sets side to side do the fronts as well,
Note you can use your old bulbs for spares.
I suggest to use a dab of dilectric grease on all of the bulb ends to prevent future corrosion.
Clean the ground connection point behind the rear quarter liner its easier if you remove the rear cargo hold down first so you dont damage the liner.
Also remove the connector for the bulb control unit on the edge of the passenger side parcel tray see if its corroded,
inspect the grounds under the hood along the front pan and sides for corrosion
And as always what was the last thing that you fixed??
I just cleaned my rear panel grounds. I was nervous at first to do this but it wasn't a problem. Kind of tough to get to but doable. If I can do it anyone can.
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Team Owner
Joined: May 2004
Posts: 31,296
Likes: 4,269
From: Philly PA
here is a link to get you started otherwise the WSM will also describe how to read the CE panel connectors
http://www.moore-fun.net/928-Electri...%20primers.htm
http://www.moore-fun.net/928-Electri...%20primers.htm
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
Not sure how alan outlines it, but its got to be consistent with this documentation that I had close at hand
Looking at any plug, still in the CE panel, in situ (viewing the wires on the backs of the plugs from your vantage point leaning over the seat)
15 25
14 24
13 23
12 22
11 21
Looking at any plug, still in the CE panel, in situ (viewing the wires on the backs of the plugs from your vantage point leaning over the seat)
15 25
14 24
13 23
12 22
11 21
Team Owner
Joined: May 2004
Posts: 31,296
Likes: 4,269
From: Philly PA
Worf wrote this , and Chris posted excellent pictures.
CE Panel Connectors: What you need to know about them to begin reading the WSM is molded on to the plugs (difficult to see, perhaps, but there.)
- Labeled A to Z from left to right and colored-keyed with the panel sockets
- For each plug the left-bank is "1" the right bank is "2"
- For each bank the bottom connection is "1" and the top is "5" (IIRC, double-check this yourself with your Mark I eyeball.)
Thus A25 is the left-most plug, top connection, right bank. Q13 is the "Q" plug, left bank, middle connection.
Once you know the connection number you can go to the WSM and begin identifying the circuit.
CE Panel Connectors: What you need to know about them to begin reading the WSM is molded on to the plugs (difficult to see, perhaps, but there.)
- Labeled A to Z from left to right and colored-keyed with the panel sockets
- For each plug the left-bank is "1" the right bank is "2"
- For each bank the bottom connection is "1" and the top is "5" (IIRC, double-check this yourself with your Mark I eyeball.)
Thus A25 is the left-most plug, top connection, right bank. Q13 is the "Q" plug, left bank, middle connection.
Once you know the connection number you can go to the WSM and begin identifying the circuit.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 170
Likes: 0
Latest development. Flasher issue solved, it ended up being a bad light 
Tail light is a different story though. I get a solid 12V at S23 but no power at the rear connector. Is there a terminal on the CE panel that is supposed to have a direct link to the connector in the back? If so I could start by checking for continuity...
Tail light is a different story though. I get a solid 12V at S23 but no power at the rear connector. Is there a terminal on the CE panel that is supposed to have a direct link to the connector in the back? If so I could start by checking for continuity...
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
The wire leaving S23 enters a bundle and runs up to the outside edge of the passenger package tray. Tucked up in a little cutout in that package tray, against the side of the car, is the bulb comparator unit.
The plug into the unit includes S23.
The unit processes the signal inside, then sends the signal out through another wire in the plug towards the back right corner of the car.
(harness actually divides off and runs wires along the sill under the carpet, towards and behind the quarter panel towards the trunk).
So,
S23 enters the bulb comparator on terminal 5 (grey/redstripe)
It leaves on terminal 3 (also grey/redstripe) and heads back to the rear connector.
The terminals should be marked on the bulb comparator box or else on the plug, I forget.
Easiest to remove the package tray for access in my opinion.
The plug into the unit includes S23.
The unit processes the signal inside, then sends the signal out through another wire in the plug towards the back right corner of the car.
(harness actually divides off and runs wires along the sill under the carpet, towards and behind the quarter panel towards the trunk).
So,
S23 enters the bulb comparator on terminal 5 (grey/redstripe)
It leaves on terminal 3 (also grey/redstripe) and heads back to the rear connector.
The terminals should be marked on the bulb comparator box or else on the plug, I forget.
Easiest to remove the package tray for access in my opinion.
