Hey folks,
quick question as this may help others with similar common problem ...........does the suspension control module located behind the RH rear compartment panel control all air suspension adjustments including PASM and sport/normal/comfort modes or does PASM have it's own separate module? Keep getting the occasional 1772 suspension amber warning CEL but after reset with icar scan dongle and NOT touching mode switch driving in normal mode no error.........yet! Thinking may have an issue with control module? TIA

 

Last Edit. I promise.

First off, have you redone the splices under your carpet?

But to your question, from the Service Manual:

NOTE: The basic equipment of the Cayenne includes the level control module. The
PASM function (Porsche Active Suspension Management) can also be
integrated into the level control module. This enhanced control module is
known as the level control module with PASM. The assembly and service
number are identical for both control modules. The following troubleshooting
diagnosis can be applied to both control module types. To simplify matters, the
control module is always referred to as the level control module in the following
description. An independent check must therefore be made to ascertain which
type of control module is installed. The difference between the two types of
control module, from the point of view of diagnostics, is that the fault codes
0142, 0143, 0144 and 0145 cannot occur for the level control module. In
addition, various menu and selection functions in the 9588 Porsche System
Tester II are not used.

 

More info:

FAULT CODE 1772

PRESSURE TRANSMITTER SIGNAL LEAD

Diagnostic conditions

• Ignition on
• Internal function test on level adjustment control unit

Possible cause of fault

• Leak in the compressed air lines
• Short circuit to B+ in the wiring of pin 84 of the level adjustment control unit
• Short circuit to ground in the wiring of pin 84 of the level adjustment control unit
• Open circuit in the wiring of pin 84 of the level adjustment control unit
• Level adjustment control unit receives implausible signal from pressure transmitter
• Pressure transmitter faulty
• Level adjustment control unit faulty

Affected pins

Level adjustment control unit, connector A:

• Pin 34

Level adjustment control unit, connector B:

• Pin 84 'P signal'

Solenoid block, connector A:

• Pin 8
• Pin 9 'P signal'

 

Thanks for the info, when you say "splices under carpet" are you referring to wiring damage caused by water? May be worth a look, car is R/H drive so wiring should be on driver side correct? Doesn't appear to have had water issues as pretty dry under there when first purchased car. Would be nice to have the correct tester to follow all the steps. Do you know if the pressure transmitter sensor is located on compressor or another location? Tia

 

Delete

 

The pressure sensor is located in the valve block. See P signal

 

Ok thanks, just to clarify to replace pressure sensor the valve block assy needs to be replaced? Tia

 

Yes it's part of valve block assembly. However, valve blocks don't fail as often so I would say do some more troubleshooting first. Check for air leaks on the valve block and compressor and anywhere else you can easily see/hear, check wiring like the other poster mentioned, change ride hight up/ down to see how the system behaves.
What other symptoms are present?
Does the compressor run more than normal? Could be failing compressor, you could try rebuilding it https://www.ebay.com/itm/151313067248 or replacing it.
Any corner of the suspension sits up high? Check pressure valve at the air spring

 

Thanks for helping with this little issue of mine. Have been slowly working through this for some time now as it doesn't throw 1772 code every time it's driven, not a daily drive only driven few times a week so it can go weeks with no code. Have covered around 200km since last amber CEL. The last time it coded the pump was cutting in more than usual so I deliberately shut car off halfway through pump cycle..........hasn't coded since which doesn't make a lot of sense (trying to get a hint as to what it could be).. Bags hold air fine, measured from wheel center to wheel arch no or few mm change over night. System calibrates fine using icarscan dongle, goes through all suspension settings/heights no problem, PASM cuts in automatically as it should when driven hard, No visible air loss using soapy water. It only codes when driving normally after about 30 min, most of the time a restart will reset and erase code for a while. I don't know how many times it's been jacked up without switching off suspension system prior to my ownership. Do you know what damage to which parts this can cause? It coded few months back after new tyres fitted so I doubt they did the right thing (could be a hint). Are you referring to checking wiring under carpet due to water or another area of concern? Realise not a major critical issue but annoying as I like to have things right.

Iv'e done the following to date..........

Replaced both front residual pressure valves (good quality German parts)
Fitted XR8 pump piston ring kit (have since read that these aren't great maybe I need a "Bagpipe Andy" kit) pump now quieter seems to not run as long approx 30sec. Pump did run every time at start up but not since rebuild so indicates holding air better now.
Checked for air leaks
Recal system a few time successfully with zero error during recal.
Removed control module checked wiring/connections, opened up to check for moisture/bad solder joint etc
Fitted 4 new tyres with correct pressure 38/42

Hope this makes sense & appreciate your thoughts. Tia

 

I try to avoid writing snippy comments, but you've tried about every possibility other than the one I suggested at the onset in bold.
The repair can be performed in a half hour with a few 2 cent butt connectors and a crimp tool.

 

I was too lazy to provide this info earlier. My apologies.
Here is my experience:
https://rennlist.com/forums/cayenne-...e-gremlin.html
A bad splice also caused my PSM to stop working, all fixed now.

 

Ok thanks for the info Steve.........finally got back to my issue on here. I did ask for more info in previous reply so it all makes sense now and I thank you. I see in your photo it appears there are aprox 4 wires "spliced" together with others, I take it these are the problem areas not single wire connectors? Like you I have no evidence of moisture and I have cleared the water drains (PITA of a job those inner guards) which were were still draining but had a bunch of rubbish in them. Will let all know what I find when I get to it. Still no code yet!

 

Apologies for late update but thought I'd share story after giving this thing plenty of time to code again. It's been 6 weeks and about 1500km now with ZERO fault after shutting off air pump part way through cycle! With the exception of checking splices under carpet contained in plastic box with no sign of moisture or wire damage, that's all I can put it down to Being RH drive the carpet removal to allow access to all of the loom is gunna be tricky so leaving until/if throws 1772 code again.

Not convinced it won't throw another code but until it does My 05 S pig is driving very well with NO codes stored after recent scan!

Many thanks to all for your input.

T

 

Cool. No reason to remove the carpet, you can just fold it out of the way on the left and right sides.