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i have been plagued by Intermittent PSE vacuum pump issues for some time. I have taken the unit apart and it looks clean inside. tested for leaks in the circuits and it ”seemed” ok.
Typically the pump doesn’t activate when I use the remote key fob and the PSE cannot be accessed using Star. If I take the connector plug out of the back of the pump, it will reset and start working again, but only if the battery voltage is higher than about 12.6volts when it is reconnected.
After a reset, if I leave the car overnight on a trickle charger, the PSE will continue to work, but if I allow the battery voltage to drop, the pump stops working. I haven’t heard the pump cycling when it’s not being used, I would have thought if there was a leak I would hear the pump activate and also that it might shut down a branch of the air circuits but the pump itself would still be accessible by Star.
Could it be a problem with the PSE internal circuit board or is this behavior consistent with a leak.
As I understand your post, if the voltage is 12.6 or higher the pump works fine and you can access the pump with Star Diagnosis; if the battery voltage is lower, then you can not. If that is the case, then your pump is surely defective. I'd use Star Diagnosis to view what faults and events are stored.
Overnight on the trickle charger and the trunk battery shows 13.54V. The remote opens the doors. I can see the pump on Star and there are no fault codes. I can also open the central locking and boot using the Star actuations.
I could buy yet another trunk battery, but I'm not confident the voltage will always be high enough to prevent the pump dropping off the CAN bus.
So that leaves me with finding another pump or replacing the PCB in the pump ? Any other ideas ?
After the initial drop when I disconnect the charger, the voltage drops from 12.92 to 12.78V over a 24 hour period.
It looks like my voltage drop theory might be busted though.
After 24 hours, the Remote Keyfob would not open the doors, but the indicators would flash and the headlamps come on.
Put the car back on the trickle charger. I then disconnected and reconnected the PSE pump connector, the central locking function was restored but I still could not connect to the PSE on Star. Two hours later the central locking is still functioning okay...
My new observation is that after 5 or 6 hours the Remote keyfob is not longer opening the door, but still flashes the indicators and turns on the lights. But if I press the boot open lever, the Pump charges up and the remote will operate the central locking again. Its as if the boot handle "wakes up" the pump.
That may literally be what is happening. The handle is wired to the pump. In contrast, when you use the remote there is no hard-wired signal -- the pump is activated by a message received on the vehicle's communication network (CAN). Communication from your SDS multiplexer is also over the CAN.
I'd remove the electrical connector to the PSE and inspect both male and female contacts. If all looks good, and if your SDS can communicate with the roof controller at a time when it can not communicate with the PSE, then I might replace the PSE.
