Curious brake light issue
11-09-2021, 12:06 AM
#1
Rennlist Member
Thread Starter
Curious brake light issue
2006 Cayenne S
Boys and girls, I've got a curious issue with my wife's Cayenne. I'm getting a "check rear brake lights" message on the display. The brakes work fine and the center brake light bar functions properly. However, the rear brake lights don't function. I'm getting the code(s), 0987 Left Brake Light and 0988 Right Brake Light. I recently changed the transmission fluid/filter and it shifts just fine. The only reason I mention the tranny is the code numbers through a google search indicated tranny fluid pressure issues although my scanner says brakes as above
I've read that it could be a fuse, which clearly is an easy fix. Also, I could simply try replacing the bulbs, but what are the odds of both going simultaneously? Pretty odd...
Whaddaya you think?
Boys and girls, I've got a curious issue with my wife's Cayenne. I'm getting a "check rear brake lights" message on the display. The brakes work fine and the center brake light bar functions properly. However, the rear brake lights don't function. I'm getting the code(s), 0987 Left Brake Light and 0988 Right Brake Light. I recently changed the transmission fluid/filter and it shifts just fine. The only reason I mention the tranny is the code numbers through a google search indicated tranny fluid pressure issues although my scanner says brakes as above
I've read that it could be a fuse, which clearly is an easy fix. Also, I could simply try replacing the bulbs, but what are the odds of both going simultaneously? Pretty odd...
Whaddaya you think?
11-09-2021, 08:55 AM
#2
RL Community Team
Rennlist Member
Rennlist Member
Disconnect the battery ground at the front driver's seat. You can do this with just the nut and don't need to lift the seat. Leave it disconnected for 10 minutes then reconnect. That will reset the bulb control module and might restore the brake function with these cars sometimes when they log a bulb error, they cut power to that circuit until the module is reset.
If that doesn't work, replace both rear brake light bulbs at the same time so the resistance is the same on both sides (BTW, the 928 is very sensitive to this).
If that doesn't work, replace both rear brake light bulbs at the same time so the resistance is the same on both sides (BTW, the 928 is very sensitive to this).
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fast_freddy (11-09-2021)
11-09-2021, 12:30 PM
#3
Rennlist Member
Thread Starter
Disconnect the battery ground at the front driver's seat. You can do this with just the nut and don't need to lift the seat. Leave it disconnected for 10 minutes then reconnect. That will reset the bulb control module and might restore the brake function with these cars sometimes when they log a bulb error, they cut power to that circuit until the module is reset.
If that doesn't work, replace both rear brake light bulbs at the same time so the resistance is the same on both sides (BTW, the 928 is very sensitive to this).
If that doesn't work, replace both rear brake light bulbs at the same time so the resistance is the same on both sides (BTW, the 928 is very sensitive to this).
11-09-2021, 05:13 PM
#4
I would first check the obvious fuses and bulbs before resetting computers. Both the high brake and side brake lights are co trolled by the rear comfort module. If the high brake light works, the module input is ok, and everything before it. Your issue is on the side light cct (which is seperate from the high light). So its either power supply (fuses), the relay within the controller, or an issue on the output side. Fuse is the easiest to check
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fast_freddy (11-10-2021)
11-10-2021, 12:35 AM
#5
Rennlist Member
Thread Starter
Did the 10 minute disconnect negative ground trick. Bupkis. I'll do the fuse trick then the bulb trick. Hopefully either will work. Daylight is the lacking commodity for me now as I've been putting in 70 hour weeks lately and the only time I've got is after 9:30PM and no garage space until a week or so from now.
11-11-2021, 01:14 AM
#6
Rennlist Member
Thread Starter
No joy thus far. I checked the fuse, as far as I can tell it's fuse #38 (10 amp) on the left side (drivers - I assume) and there was nothing there. I slotted a 10 amper in there. Nothing. Perhaps it's the other side. Gonna try the bulbs and check out the other side tomorrow.Fingers crossed.
11-12-2021, 12:01 AM
#7
No joy thus far. I checked the fuse, as far as I can tell it's fuse #38 (10 amp) on the left side (drivers - I assume) and there was nothing there. I slotted a 10 amper in there. Nothing. Perhaps it's the other side. Gonna try the bulbs and check out the other side tomorrow.Fingers crossed.