HELP!! Taillights and Third Brake Light will not go off!!

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krell600

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I desperately need help. My girlfriend is home with my LS and I am 700 miles away on business and I need some help. As of today, my 2004 LS's taillights and third brake light stay on all the time and will not go off, even when the car is off. I just installed a brand new battery last week. Any suggestions? Thanks in advance!!
 
Sounds like the brake light switch. Look at the brake pedal bracket (under the dash) and see if there is anything causing it to stay on. The switch could also be bad.
 
Could be the brake light switch, the Rear Electronics Module, or a short in the harness somewhere.

Here's what the Repair manual for the 06 says about it (should be the same for 04).

Normal Operation — Vehicles With Stability Assist

Each stoplamp is supplied battery voltage independently. The stoplamp ground circuits are independently controlled by the REM. When the brake pedal is applied, the stoplamp switch allows voltage to flow through circuit 29S-CF1 (OG/BU) to the anti-lock brake system (ABS) module. The ABS module then sends voltage through circuit 29S-CF2 (OG/BU), which is spliced to carry the voltage to the PCM and the REM. Voltage to the REM (from the ABS module) after the splice is carried through circuit 29S-DK30 (OG). When the REM receives voltage from the ABS module, the REM grounds circuits 31S-LG6 (BK/YE) (high mounted stoplamp), 31S-LG14 (BK/OG) (LH stoplamp) and 31S-LG21 (BK/GN) (RH stoplamp) to illuminate the stoplamps. The electric parking brake can also trigger the stoplamps by communicating to the REM (via the SCP link) that the parking brake has been actuated while the vehicle is moving.
Click to expand...

First try unplugging the brake light switch under the dash and see if they go out. If that doesn't do it you'll have to start digging around into wiring harnesses and all that mess.

Here's a link to the manual, it may come in handy.

http://deneau.info/ls/s6x~us~en~file=s6xh1005.htm~gen~ref.htm#extract_315

http://deneau.info/ls/
 
lots of crap to check :rolleyes:

Pinpoint Test O: The Stoplamps Are On Continuously

Normal Operation — Vehicles Without Stability Assist
Each stoplamp is supplied battery voltage independently. The stoplamp ground circuits are independently controlled by the rear electronic module (REM). When the brake pedal is applied, the stoplamp switch allows voltage to flow through to circuit 29S-CF1 (OG/BU). Circuit 29S-CF1 (OG/BU) is spliced to carry the voltage to the powertrain control module (PCM) and the REM. Voltage to the REM (from the stoplamp switch) after the splice, is carried through circuit 29S-DK30 (OG). When the REM receives voltage from the stoplamp switch, the REM grounds circuits 31S-LG6 (BK/YE) (high mounted stoplamp), 31S-LG14 (BK/OG) (LH stoplamp) and 31S-LG21 (BK/GN) (RH stoplamp) to illuminate the stoplamps. The electric parking brake can also trigger the stoplamps by communicating to the REM (via the communication network) that the parking brake has been actuated while the vehicle is moving.

Normal Operation — Vehicles With Stability Assist
Each stoplamp is supplied battery voltage independently. The stoplamp ground circuits are independently controlled by the REM. When the brake pedal is applied, the stoplamp switch allows voltage to flow through circuit 29S-CF1 (OG/BU) to the anti-lock brake system (ABS) module. The ABS module then sends voltage through circuit 29S-CF2 (OG/BU), which is spliced to carry the voltage to the PCM and the REM. Voltage to the REM (from the ABS module) after the splice is carried through circuit 29S-DK30 (OG). When the REM receives voltage from the ABS module, the REM grounds circuits 31S-LG6 (BK/YE) (high mounted stoplamp), 31S-LG14 (BK/OG) (LH stoplamp) and 31S-LG21 (BK/GN) (RH stoplamp) to illuminate the stoplamps. The electric parking brake can also trigger the stoplamps by communicating to the REM (via the SCP link) that the parking brake has been actuated while the vehicle is moving.

Possible Causes
Circuit 29S-CF1 (OG/BU) short to voltage
Circuit 29S-CF2 (OG/BU) short to voltage
Circuit 29S-CF58 (OG/GN) short to voltage
Circuit 29S-DK30 (OG) short to voltage
Circuit 29S-RE13 (OG) short to voltage
Circuit 31S-LG6 (BK/YE) short to ground
Circuit 31S-LG6A (BK/YE) short to ground
Circuit 31S-LG6B (BK/YE) short to ground
Circuit 31S-LG14 (BK/OG) short to ground
Circuit 31S-LG21 (BK/GN) short to ground
Stoplamp switch
ABS module
PCM
REM
Electric parking brake module
 
Here's the switch (supposedly :shifty:)



.

brake.jpg
 
:p That took me forever too, cuz I couldn't find the section I was looking for.

I must be slipping or something. I missed the very first part about being 700 miles away. Hopefully your girlfriend has another car to drive. If you can get her to look in the manual and pull the main fuse(s) for the stop lamps, or disconnect the battery, that will keep the lights from draining the battery until you can get there to fix it. Either that, or she's probably gonna have to take it to a shop, or dealer to have them fix it. Unless she knows a lot about fixing cars, and testing circuits, and all that fun stuff.
 
lol, I missed that too. I thought the he was 700 miles away on some road trip WITH the LS. :lol:
 
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