R230 CAN bus voltage issues

[toza]

When I first purchased the car last year there was a severe battery drain and other issues with headlights etc that led me to replacing front passenger SAM and for a couple of months everything was fine until I then started getting new errors for brake fluid level, hand brake left on, issues with wipers and the outside air temp sensor was giving strange readings (50-60°C). Conscious that all of these are associated with the SAM I replaced I swapped the old one back thinking these new issues might disappear, but all this achieved was for the old problems to come back and provide company for the new issues. In addition to these issues more recently the PSE pump stopped working and the roof won't open as it thinks the separator isn't closed.

One thing to note is that there has clearly been water entering the boot for a while and both boot surround seal + rear window bottom seal both need replaced from the looks of things. I started digging around in the boot when the PSE pump started working and found the bottom part of the connector where the power pins are had quite a bit of corrosion and the foam was really wet but have since cleaned all of this up.

More recently I started looking at possibility of issue with CAN network and took voltage reading from CAN B connector X30/15 (passenger side) - On one strip of the connector (brown) I get 0.02V but on the other (brown/black) there is no voltage at all. As part of recent investigation also installed new rear battery.

List of current error codes (there were about another 30 odd historic that I cleared):
- Control module A37 (PSE Control module combined) OR (199) control module ACL (ZLB) is not transmitting data on the CAN bus
- B12 (refrigerant pressure sensor) OR B12/2(Refrigerant pressure and temperature sensor 1) - the component is fault or the lead has a short circuit
- No or incorrect CAN data from control module A37 (PSE control module (combined))
- Fault in CAN communication with control module Driver signal acquisition and actuation module
- Fault in CAN communication with control module N60 (Central locking (CL) control module)

If anyone has idea of where to look next I'd greatly appreciate any guidance as I'm running out of ideas and any mechanics or auto electrician's locally don't want to touch it.

 

[SL63 Mark]

Have you checked the SAM connector under the passenger carpet for corrosion, that often sits in water, corrodes, and causes random faults. The water enters via the heater box because the drain plug is blocked. Check the foam carpet underlay for damp. It is very thick and holds a good few litres.

There are connectors in other places too, all brilliantly designed to get wet and corrode.

Welcome to the forum by the way.

 

[toza]

Have you checked the SAM connector under the passenger carpet for corrosion, that often sits in water, corrodes, and causes random faults. The water enters via the heater box because the drain plug is blocked. Check the foam carpet underlay for damp. It is very thick and holds a good few litres.

There are connectors in other places too, all brilliantly designed to get wet and corrode.

Welcome to the forum by the way.

Yes, had the passenger seat out and took up the carpet to check all the wiring connectors running through that channel. That's where I took the CAN B voltage readings. All dry and no sign of corrosion on any of the connector blocks.

Separately I removed the PSE pump and disassembled - seems the motor is gone as while I can freely spin, when I apply 12v directly it 'chugs' around a bit but never spins constantly so will work to resolve that issue first. Strangely I read in another thread that PSE problems will lead to "separator isn't closed" error so hopefully two birds with one stone.

 

[s5tuart]

Yes, had the passenger seat out and took up the carpet to check all the wiring connectors running through that channel. That's where I took the CAN B voltage readings. All dry and no sign of corrosion on any of the connector blocks.

Separately I removed the PSE pump and disassembled - seems the motor is gone as while I can freely spin, when I apply 12v directly it 'chugs' around a bit but never spins constantly so will work to resolve that issue first. Strangely I read in another thread that PSE problems will lead to "separator isn't closed" error so hopefully two birds with one stone.

It may be that regarding the PSE pump that the impeller vanes are shot and just need replacing.

 

[toza]

It may be that regarding the PSE pump that the impeller vanes are shot and just need replacing.

Thanks Stuart for reply. Impeller vanes are all intact- had them removed when I was testing motor so pretty sure replacement motor is in order.

 

[peterws1957]

Thanks Stuart for reply. Impeller vanes are all intact- had them removed when I was testing motor so pretty sure replacement motor is in order.

I'm sure you've checked and are already aware that it appears critical when rebuilding the pse that the fixing screws are tightened just right. One video shows the guy using a pressure gauge and how the smallest turn of the screws affects the function to a large extent.

 

[ajlsl600]

All of benz r and d and they can't keep boots dry, or pass side footwell, where blocked but un published drains leak too! Then they install critical electronics there. If that's not dtf I don't know wot is. An d if you evade that you hav oil wicking along trans harness to tcu. Hardly great design.