So my buddy has an 05 cayenne that failed inspection because the speedo isnt working. It also has a bunch of codes and electrical issues as well as the battery was junk so i replaced the battery. Still bunch of codes but Ill stick to the ones i think are related;

P0503- vehicle speed sensor signal psm/asr no signal

U0129- communication psm control unit no signal

P1606- communicatio psm control unit signal implausible

U0104- transmission control unit fault signal implausible

These last two maybe maybe not related to speedo or psm

P1613- gateway communication (can drive) signal implausible

P1614 communication steering wheel electronics (can drive) signal implausible
(I pressed the volume up button on the steering wheel and it worked.)

Now the weird thing is there is no psm lights on the dash lit up. When i press the psm off button the light doesnt come on and nothing on the instrument cluster. The dial in the center console to put in 4x4 isnt working and he said its stuck in 4x4.

The ABS light is on as well as flashing red brake light i changed the first fuse in the forth row in the passenger side fuse box but no changes. Also the front left brake pad wear sensor isnt in the brake pad, and two wires coming from that pad wear sensor are broke, but no lights on the instrument cluster for it.

Also on the dash it says something like brake proportion warning? And something like ignition lock i think? At first he had trouble getting the key out, but i had no problems n i took it out a few times, and i cant access the menu with the button on the directional stalk.

I have no idea where to go from here and i hate just throwing parts at cars. I read it could be a bad alternator (but i had it running for couple hours and there was no drop in the voltage gauge or warning light) or it could be a bad speed sensor at the transmission?

Sorry for such a long post, i just wanted to give as much info as i could. Im just so stuck at this point and dont know what to do next aside from throwing parts at it but i hate doing that blindly without testing things. Also it's tough because he's like 45mins away from me and it took the car off the road a few months ago, and just now had me come look at it

 

The first fault code ( P0503) indicates a possible failed Vehicle speed sensor , all the other codes (except P1614) could be as a result of the lost VSS signal.
Speed signal is used by ABS and PSM . You should be able to read speed signal from each wheel in the ABS control unit, and determine if it is, or which one is the problem.

'Also the front left brake pad wear sensor isnt in the brake pad, and two wires coming from that pad wear sensor are broke, but no lights on the instrument cluster for it."
it is possible the wires on the car side were bridged to defeat the brake pad warning.

 

Thank you for replying. Ya i figured it was all mostly related to the VVS and that ties into the ABS/PSM. Other vehicles i have scanned always said which wheel speed sensor was the fault, for some reason this one isnt, and for some reason when i tried to get into the ABS module with my scanner, it wouldnt communicate. Is there another way i could figure it out? Some where else i was reading said it was likely the vvs at the transmission. Its just weird that the ABS light is on the dash as well as the brake proportion warning, but not PSM warning, pressing the PSM or traction control button does nothing, not light on the button and no indicator on the instrument cluster. Then there's the issue with the selector in the center console for 4x4, ect isnt doing anything either.

Ya the brake wear sensor is there, but its like it fell out of the brake pad or someone forgot to put it in. Im not sure the broken wires are on the car side or definitely to the wear sensor. Its in the same harness, i just didnt get a close enough look at it because it was dark, cold, i had just finished replacing his struts and it was getting late so i just wanted to get out of there and get home. I wish i had taken a picture of it.

 

Hello,

I'm having the EXACT SAME symptoms. Along with terminal 30 implausible and i have Zero brake lights, running/ turn/rev lights work. Did you ever resolve your non- wheel specific ("A") speed sensor code?

Scanner sees front 2 wheel speeds but doesn't even have the rears as an option to see, which is weird. Scanner see brake switch activation and brake light switch activation but no brake lights turn on.

Things I've done:
Replaced both batteries with H8.
New Cardan shaft
Re-spliced every connector under both sides of carpet.
Checked All fuses.
Replaced 433 relay.
Replaced all 4 wheel speed sensors.
Cut and checked FR ABS harness.
- there is more I just can't think right now haha

More to come:







I purchase a $1200 Autel Scan Tool because the icarsoft POR-11 wasn't specific enough. Seems this scan tool pointed me to look at a couple relays i hasn't taken notice of before. Upon inspection of said relays, I noticed they were burning hot... I didn't bother testing them as this was last night, I'm replacing them with new layer today, as preventative maintenance for any future failures.

I purchased this at auction and it seems the previous owner had curbed it really bad. The air suspension is slightly lower on the front right and from researching forums I decided to buy a new valve block, going this will solve the air suspension issues. But again it's locked bc of the ABS code so I can't even test its functionality until I resolve the BRAKE PROPORTIONING WARNING...

Also there was water intrusion into the left brake light when I received the car and the brake lights actually still worked under water.. when I replaced the tail light assembly is when all brake lights stopped working, again reverse, blinkers and running lights work.

I'll try to update later after I replace these relays.

Thanks.

 

I'm still having this problem did you figure out what the issue was?