touareg

Found this interesting, there are a TON of things that will cause the PSM to switch off, and cause the car to go into limp mode.

bambar

Thanks for sharing.
I also read somewhere that it can be triggered by badly aligned wheels. But this could be covered in 'Steering-angle sensor'.

touareg

Yes, these are just the codes that can be on the PSM (not the DME). I have heard of tire specs being off (1 was worn down out of spec causing the PSM to stop and system go into limp)

The PSM module has two sets of can-bus networks, it has the can-drive, which it gets data from anything on the network, but it also has can-private, it's own network for gathering data. I think if anything on that network has issues the PSM disables.

But yes having a wheel sensor fail disables PSM (makes sense if you have no idea what is going on with a wheel you can't adjust things on the fly for traction)

Orantes

Great information. I have random PSM failures at the moment. All I seem to get is the "1314 DME control module" error code. From reading many posts I am led to believe this could be due to an failing battery....but that could be just wishful thinking....

2004 CS

touareg

Well I have the same code, and I spent 2 hours last night going over the wiring diagram for the PSM module as well as can-bus stuff in general to get a good understanding of any wiring issues. I am impressed actually with all the backup power to many critical modules, 2 or even 3 hots, multiple grounds. Even the Parking brake and brake pedal actuation has multiple redundant entry points into many modules, in case one system fails.

I found one person say they needed a new DME, replaced and fixed their PSM problem but I am not convinced that was the problem, removing and reconnecting could have been the issue.

This is what I know so far. I started getting intermittent SIGNAL from the temp sensor in the engine bay first, signal means it is a hard wired direct to the module, in this case the DME, then started getting the PSM error 1314, that says either broken signal or or implausible message from the DME a few months after.

Now the PSM and the DME sit on a bus, called the can-drive bus. Other modules are on that bus, but I think are mostly inside the car (Transmission for example) and are not having problems.

So after finding out the PSM is under the DME, and I suddenly have a failed temp sensor too that runs wires to the same area in the engine bay, that maybe water or something is getting in there and fouling some connections.

I have not cleaned the drains out in almost two years, so I am going to pull my new battery (from last fall) and pull the DME and PSM modules out, clean all contacts, drain areas in the cowl (and if I find a lot of stuff I have a good suspicion).

I am pretty convinced this is an electrical issue.

touareg

Another bit of info, the PSM and all the components it relies on.

Gnrnr

What document are you accessing Touareg? Some bloody useful information in many of your posts.

touareg

I forgot where, purchased a factory manual set online somewhere. Not sure if it is even correct for my car a 957 since it says 2008 which is weird.

touareg

Well cleaning the cowl drains was disappointing!

Pulled out 1 leave from one side, and a few pine needles from the other.

I have till been researching touaregs for similar problems and solutions. I found 2 that sound like they may help.

1 was pulling the DME and disconnecting the PSM, cleaning the contacts and re-assemble.

2 Another had water in their PSM and was able to repair it and solved problems.

touareg

Finally found a clue back to the 2003 era cars, maybe this is still a problem:

TSB PSM Warning Light in instrument cluster activated.

Moisture entering the PSM contact plugs in main harness may activate the PSM warning light in instrument cluster. It says grounds and multiple plugs can have corrosion.

Skipping ahead after removal of DME, just one page, of many, but I guess I know what I am doing this weekend....

J'sWorld

Is this the same "touareg" over @Renntech Cayenne?

Orantes

Touareg, I'd be interested to know if your problem is solved as per the TSB. I will also check this out over the weekend. I cannot for the life of me work out what sets off my PSM workshop light, there is no distinct pattern to the activation. Occasionally I will do a long trip and it will not activate....sometimes it comes on straight after I turn the key. Frustrating!

I wish I had a spare Cayenne so I could nail down the problem by swapping over DME & PSM modules, MAFS, throttle body, level sensors, speed sensors etc but that option isn't available!

I think I'll pray for some visible corrosion....

2004 CS

touareg

Did you have a chance to check? I did my hitch and got lazy after that!

My kessy antenna was accessible with the bumper off (and was throwing a code before), so I pulled that apart and found corrosion on the pins, scraped it down, sprayed it with electrical cleaner and it works!

So totally plausible something else like this is going on.

Researching my earlier wire problems, and relay 433 under the drivers seat (is your battery under the front passenger seat?), I found that relay powers the lower to fuse block rows in the passenger side fuse panel.

Guess what else has at least 3 fused off those two lower rows.

The PSM module.

Guess what I did to get an add-a-fuse in for my dash camera about 3 weeks before I had the electrical meltdown and the PSM errors. (verified by my postings on renlist)

I put it in the second to last row, as that was switch power.

I pulled my circuit and have had ton of rain and no problems this past week, here is hoping that the PSM is very sensitive to load on its power circuit.

I would suggest replacing relay 433 as that cured some weird issues I had earlier with the car.

Orantes

Unfortunately, I have not had a chance to check as yet. I will have a look at the 433 relay too. Yes, my battery is under the front seat. Did you replace the 433 relay, or just remove your camera from the circuit?

2004 CS

touareg

I had replaced relay 433 as I heard rumours of that causing problems, as it also powers the identity module and runs power to the OBD Diagnostics port.

I had a problem when I had a OBD adapter hooked up, and the car would have stumbling problems, remove the adapter and it is fine.

I replaced relay 433 and this resolved that problem.

I still had the PSM errors.

Removing the circuit, we shall see as time goes on.