08 Cayenne GTS with Brake Proportining warning, ABS light on and Brake light flashing on dash

[motivation]

Hey Everyone I have a 2008 Porsche Cayenne GTS V8. I have multiple symptoms, the brake proportioning warning is on, Ignition Lock-fault, ABS light on, Brake light flashing and the brake lights stay on continuously even with the car off. The car runs fine with no issues except for the warning lights on. 

The Codes I found:

1314 DME Control Module

1315 Tiptronic Control Module

1316 PSM Control Module 

0456 KESSY Control Module (CAN Drive)

0455 KESSY Control Module (CAN Comfort)

15582 Please refer to vehicle service manual!

15583 Please refer to vehicle service manual!

0185 Relay for terminal 15 (activation) 0576 Terminal 15 Both these codes fixed by finding two broken wires (corroded), cut the wires and re-spliced them together. 

1312 CAN drive

 

I've found numerous forums on this website that helped me fix a couple of the issues, but not most of them. I checked for both front foot well carpets being wet, found passenger front foot well drenched wet. I pulled the passenger front seat out of the vehicle, pulled back the carpet and found a little water build up. I checked all the a/c drains cleaned them out, but found no water come out. Checked the sunroof drain hoses, found them good, checked the evaporator drain and found it to be good also.  Cleaned and dried the water out from the passenger front foot well, checked the wire loom and found three broken wires, repaired all three wires. Still none of the symptoms were fixed by fixing those wires. Pulled the driver side seat out and pulled the carpet back, found three wire broken their, repaired them. Two of those wires were for the relay 15 that helped fix the ignition lock fault. Fixed a third wire and found corrosion on four black thick wires combined as a sonic weld. Cut the wire and repaired them, those did not fix any of the symptoms. I checked all three fuse box locations, driver and passenger fuse box and engine compartment fuse box. Found all the fuses good. I checked all the ABS wheel speed sensor and the wires that go to the brake pads, they all seemed in good condition. Checked the battery and found it to be good, but still replaced it just in case with another new battery. Still the same issues, replaced that battery with another new one, just wanted to rule out battery for sure, still found same symptoms. I disconnected the battery for 30 minutes and cleared codes, but still the codes return immediately and the lights also (getting irritated right about now). I disconnected the ABS Module, but the warning lights are still on, I was thinking maybe the ABS Module was bringing down the system, this check I don't think still eliminates the possibility of the module being bad. The brake lights always stay on, when disconnecting the ABS module the brake lights turn off, but when reconnecting the brake lights stay back on. I believe on these newer Cayenne's that it does not have a brake pressure switch, but instead the signal voltage for the brake lights are sent by the ABS Module. I checked the ground wires (thick brown colored wires) for any corrosion none found (checked 8 different ground points on vehicle). I found after market head unit and disconnected it, but found nothing to change. I think perhaps the ABS Pump with Module and DME are bad or maybe something else, but I don't wanna take a guess since those items are extremely expensive. Any help would be greatly appreciated!

[lewisweller]

7 hours ago, motivation said:

Hey Everyone I have a 2008 Porsche Cayenne GTS V8. I have multiple symptoms, the brake proportioning warning is on, Ignition Lock-fault, ABS light on, Brake light flashing and the brake lights stay on continuously even with the car off. The car runs fine with no issues except for the warning lights on. 

The Codes I found:

1314 DME Control Module

1315 Tiptronic Control Module

1316 PSM Control Module 

0456 KESSY Control Module (CAN Drive)

0455 KESSY Control Module (CAN Comfort)

15582 Please refer to vehicle service manual!

15583 Please refer to vehicle service manual!

0185 Relay for terminal 15 (activation) 0576 Terminal 15 Both these codes fixed by finding two broken wires (corroded), cut the wires and re-spliced them together. 

1312 CAN drive

 

I've found numerous forums on this website that helped me fix a couple of the issues, but not most of them. I checked for both front foot well carpets being wet, found passenger front foot well drenched wet. I pulled the passenger front seat out of the vehicle, pulled back the carpet and found a little water build up. I checked all the a/c drains cleaned them out, but found no water come out. Checked the sunroof drain hoses, found them good, checked the evaporator drain and found it to be good also.  Cleaned and dried the water out from the passenger front foot well, checked the wire loom and found three broken wires, repaired all three wires. Still none of the symptoms were fixed by fixing those wires. Pulled the driver side seat out and pulled the carpet back, found three wire broken their, repaired them. Two of those wires were for the relay 15 that helped fix the ignition lock fault. Fixed a third wire and found corrosion on four black thick wires combined as a sonic weld. Cut the wire and repaired them, those did not fix any of the symptoms. I checked all three fuse box locations, driver and passenger fuse box and engine compartment fuse box. Found all the fuses good. I checked all the ABS wheel speed sensor and the wires that go to the brake pads, they all seemed in good condition. Checked the battery and found it to be good, but still replaced it just in case with another new battery. Still the same issues, replaced that battery with another new one, just wanted to rule out battery for sure, still found same symptoms. I disconnected the battery for 30 minutes and cleared codes, but still the codes return immediately and the lights also (getting irritated right about now). I disconnected the ABS Module, but the warning lights are still on, I was thinking maybe the ABS Module was bringing down the system, this check I don't think still eliminates the possibility of the module being bad. The brake lights always stay on, when disconnecting the ABS module the brake lights turn off, but when reconnecting the brake lights stay back on. I believe on these newer Cayenne's that it does not have a brake pressure switch, but instead the signal voltage for the brake lights are sent by the ABS Module. I checked the ground wires (thick brown colored wires) for any corrosion none found (checked 8 different ground points on vehicle). I found after market head unit and disconnected it, but found nothing to change. I think perhaps the ABS Pump with Module and DME are bad or maybe something else, but I don't wanna take a guess since those items are extremely expensive. Any help would be greatly appreciated!

 

Wow big headache and you done well to fix a lot so far. The brake light switch is in fact a hydraulic pressure switch on the brake master cylinder which will send a signal to Rear Comfort control module (located right side of boot with CD changer same place)  or via the abs module first but not sure. The fact you found so many corroded or broken wires will either mean you have some more to find or the component(s) associated got damaged during the wiring issues time. 

Sorry can't be more help this is nightmare fix without Porsche software. Good luck and keep us posted. 

[jagman1]

I had the terminal 15 relay go bad and cause many of those same errors. The relay is located under the drivers seat. It can be accessed by moving the seat all the way forward and up. Or by unbolting the seat as if you were accessing the battery. The relay is a little black box. I tapped on it with the ignition on and all my problems went away. $30 for a new one and fixed. I figured this out after exploring the front carpets for water intrusion and broken splices.

[motivation]

Thank you for the replies. I swapped the relay from the Engine Compartment with the terminal 15 relay, but still had the same symptoms. The Kessy has most of the codes stored, I'm thinking maybe something with the CAN Bus could be wrong?

[motivation]

Anyone?

[touareg]

Did  you ever fix this? I am tracing down some problems too. I found 3 corroded wires in the drivers side, also replaced the relay under the drivers seat.

 

While improved, did not fix all my problems.

 

Looking to do the passenger side next I suppose.

[Tim Rashed]

I know i am jumping on an old thread but i have the same issue.

 

My have a porsche cayenne 2008 is throwing a "Brake Proportioning" error and refusing to start.

Checked under the driver seat carpet and found water, dried it out, and repaired corroded wires.

That worked for a while until i replaced the brake pads and rotor, could be a coincidence but i rechecked the wires, they look fine, also checked the brake sensors.

Tried to disconnect the battery for 30 mins and reconnect it to reset the computer, no luck

Even though the brakes are installed correctly and the wiring is in tact, it just won't past that error and won't start.

Any help or advise would be appreciated

Here’s the picture of the error if that helps

https://imgur.com/a/3VrVuFE