[idainc]

I got this message and all bulbs are intact. Just the drivers side is out (the bulb is OK ) Regardless I replaced it. Fuses OK. The wiring diagram shows all brake lights controlled by relay so that's not it. I sprayed the contacts in the offending brake light socket and pried them out and still no luck. All fuses OK as well.

I am suspecting a local wiring issue that I cant see and considering replacing the harness for about $60. Cant imagine anything else.

All ideas greatly appreciated.

 

[hoonk]

What year car?

 

[idainc]

2004. Interestingly enough the part # for the harness is different for the right side than the left. The pictures from parts places are identical with one noting "fog light" or no "fog light" all models of the car have a marker light on the side of the bumper/

 

[hoonk]

Using your $5 test light - do you have power at the green wire going to terminal #5 on both the left and right taillamps?

 

[volvogod]

3/9 is the brake pedal switch. 3/19 is the 3rd brake light, does it turn on?, if yes the pedal switch is OK. 4/58 is the REM. See if relay RMI 5 clicks when pressing the pedal. Swap with another relay if need to test. Open the attached REM Relay PDF and zoom in to locate RMI 5 relay in the REM. The side panel will pry out some to get your hand on RMI 5 relay. Shunt 20/31 could have failed. Swap if needed. If removing shunt, inspect female shunt connectors for being burnt in REM. The 1999-2004 shunt terminals would burn on the low beams in the CEM's.

 

[idainc]

3RD brake light works. Right brake light works. I am doing this alone so I cant hear if the relay clicks. If I am reading these correctly the brake lights are all “downstream” of the fuses and relay. I don’t have the $5 light but it has to be live on the right side since the bulb lights up. It must not be live on the left because it wont light up all three bulbs I have. It looks like one relay controls all three brake lights ?

Am I correct in assuming that the REM, relay and fuses all control all three brake lights and if one bulb is out it must be either the bulb or something in the harness ? The whole interior of that tail light assembly is filthy. I sprayed the socket with cleaner as well.

Thank you both.

 

[idainc]

I replaced the tail light harness with a new one and a new bulb and the condition still exists. Drivers side brake light still out. Any ideas ? In a quiet garage I can hear the relay go on and off when I step on the brake.

 

[ggleavitt]

I’m sure there are folks around here who can help further and the advice you’ve gotten so far is about as solid as it gets but I’ll see if I can help dig a little more. You have one side working, one side not. You’ve replaced the wiring harness and bulbs for the affected side with the same result. As this vehicle is a 2004, you have a different harness than the vast majority of owners (changes in 2005 along with CEM and REM).

Really, the best thing to troubleshoot this with is an automotive circuit tester as was mentioned. They’re cheap (<$15) so no need to overdo it, you just want a 12 volt light on a probe with a ground clip.

Since I have no idea what your particulate harness looks like, I can only suggest that you visually walk the working side harness wire bundle all the way to the REM connector so you know the routing path. Remove the bulb from the working assembly and check with your light in the socket while someone presses on the brake pedal, validating the function side as a baseline of sorts. Then do the exact same thing for the side which does not work, using the working side as your reference and backup for a logical progression through the failed circuit.

I did have a chance to look into an old copy of a 2004 EWD I have lying around and I see another page (47) where the wire color (yellow) is different from the EWD version wire color (green) posted earlier. I’m adding the screenshot but don’t get too hung up on which color it is, prove this yourself by physically walking the wire. For reference, 10/18 is left assembly, 10/17 is right with A:5 being the socket designator for each side stop light. There’s supposed to be an electrical junction point for the two sides on the way to the REM (53/667), again not on any vehicle after 2005. That junction is “before” fuse F14 electrically and I believe it’s somewhere at the very back to the left of the battery, big bundle of wires I'll. That’s one place to look closely for sure.

I don’t see a PN for the harness that you replaced posted, could you please note it so we can get a visual on what it looks like and try to imagine the routing? Where exactly did it connect?

I can’t imagine this’ll be too hard to resolve if you’ll get a cheapie tester and take a few photos (with harness PN).

Please let folks know of any progress that you make, thanks.

 

[hoonk]

can’t imagine this’ll be too hard to resolve if you’ll get a cheapie tester and take a few photos (with harness PN).

Yep -
"Using your $5 test light - do you have power?"

 

[idainc]

Thank you both. This is the harness for the tail light showing the four bulbs and a socket that serves the marker light in the bumper. As i understand it the hot wire comes out of the REM and splits to go to both brake lights. The problem is between that split and the connector that attaches to the tail light harness. The problem at the moment is that I due to a family problem I don't have anyone to operate the brake pedal and assist me. My mechanic was confident he could diagnose this is an hour ($110) + repair costs. He's pretty good and done a lot of work for me so I really have to go that route. I much appreciate your help and replies.

 

[ggleavitt]

Cutoff broom handle or stick between seat front and pedal (pressing pedal), maybe that would work. For sure your mechanic can find the problem, thanks for posting the harness photo.

 

[ChitownV]

Thank you both. This is the harness for the tail light showing the four bulbs and a socket that serves the marker light in the bumper. As i understand it the hot wire comes out of the REM and splits to go to both brake lights. The problem is between that split and the connector that attaches to the tail light harness. The problem at the moment is that I due to a family problem I don't have anyone to operate the brake pedal and assist me. My mechanic was confident he could diagnose this is an hour ($110) + repair costs. He's pretty good and done a lot of work for me so I really have to go that route. I much appreciate your help and replies.

If you are not comfortable with doing wiring, then yea, take it to your mechanic.

For future reference here is a video showing how to check the power at the rear harness for the driver side rear light assembly using a $5 test light. Around the 0:45 mark is when they get into the driver side rear harness connector with the test light and the specific pin to check. Without even using a test light, you can follow the wire from this pin and see if you notice any issue with the wiring. Could be a simple fix if you can see an issue. Also look into the connector if the pin simply slid out. For just looking, you might be able to save money, or at least save money on diagnostic labor.

Checking rear harness connector when installing trailer wiring

 

[idainc]

Thanks, that's a great video. I'm always hesitant to tackle things that are more involved. This is my only car and I really depend on it. I called a few dealers in the area and beyond and I had one refer me to an outside shop (not mine) because they didn't have anyone working there who had any experience at all on "classic" cars. Never heard a dealer turn away business. Will update afterwards,.

 

[Capndirk]

For anyone needing a brake or throttle pressed with no qualified assistance available, Harbor Freight has these things available. The one end comes off and gets remounted on the other end to use it as a spreader. The pistol grip end hooks on the steering wheel, and the other presses on the pedal.

 

[John C]

Cutoff broom handle or stick between seat front and pedal

Half inch breaker bar. Motor the seat forward to press the brake pedal...

 

[idainc]

Solved. $166 for my mechanic to track down a bad ground 31/72. No more message on dash. Add another $85 for the new harness.