Hi everyone, I would like to ask for some help with an issue that I am currently investigating and trying to troubleshoot for a week now.

The vehicle is 2007 CL500 (550 for US) with the M273 engine, RWD and this is the VIN WDD2163711A003933.

A week ago while I was doing errands through town I suddenly got bombarded with various errors on the instrument cluster, loss of power steering and the speed, RPM, fuel & temperature gauges started bouncing from actual values down to 0 and back in what seemed to be 0.5/1s intervals. The errors on the cluster were ABS/ESP/Parking Brake inoperable, Run Flat inoperable, ABS mafunction, Distronic unavailable, Park Assist unavailable and they were constantly shuffling. It also seemed like input such as changing from D to P or trying to use blinkers was happening with slight delay or when the system was in that short interval of 0.5s in which the gauges were reflecting normal values. It looked like bad connection somewhere.

I turned off the car and had to leave it for an hour to do some personal stuff. When I was back everything worked normal and there was no sign of any errors - that's until I drove the car for another 10-15 minutes. The issues started happening again while idling on an intersection. The next day I went to a local electrical indy shop, they had the car scanned(not SDS, I think it was Autel) and there were numerous errors, mainly that there is no CAN communication between the different modules. It wasn't that all modules do not receive comms from a single, rather all modules had issues communicating with all other modules. The person at the shop pulled back the passenger side front carpet and unscrewed the big metal plate that holds the X30/30 CAN connector with the green wires and started pulling them 1 by 1. The erratic behaviour stopped when he pulled out one of the wires that later in the diagrams appeared to be the ESP module connection. I drove the car like that for the rest of the day and there was no more erratic behaviour, just ABS/ESP errors & no power steering since the ESP module is essentially unplugged.

Since then I've tried reconnecting back the CAN plug and there isn't any sign of the issue up until I drive for about 15-20 minutes or the car gets to roughly 90deg C operating temperature(not sure if that's related at all, maybe a coincidence). Based on this I've decided to troubleshot on my own but with no success, I've done the following:

- Checked the ESP N47/5 module plug for corrosion and re-seated it
- Cleaned with electrical contact spray the ground wire of the ESP module plug as well as the plug
- Tried to find severed wires from that connector up until the big fuse box next to the auxiliary battery
- Tried to find signs of corrosion or water ingress anywhere around all those connectors both in the engine bay and in the passenger side carpet
- Tried to wiggle around all the connections & ABS sensor wires while the ignition is on in attempt to trigger the issue to no avail
- Checked front SAM box for signs of corrosion - looks new inside
- Checked both battery voltages - main one holds 12 and aux holds 12.4 when vehicle is off, both charging above 14 as they should while running.

It's obvious that something related to the ESP module is probably shorting the chassis CAN which causes all other modules to go crazy and disconnecting it from the CAN seems to calm things down. However, I am a bit lost. In the last 7 days I've went over almost all similar threads in here and in other communities and tried pretty much anything. I don't want to start throwing parts at the car and spending big $ just to find later that it's some wire or probably loose connection. The indy shop is not interested into looking further at the issue so I might have to try & find someone else with SDS in town although not sure where to start based on the stored codes. At least the car is still drivable, engine & transmission are flawless. In the meantime, I would like to ask for some directions on what to check further and if there is a way to actually verify each part of the ESP module harness while the issue starts occurring in an attempt to find if any of the circuits is causing that short?

 

Well, I always error on the side of lots of parts, because they're all 18 years old anyway and would not hurt to replace. The wheel speed sensors can cause issues like what you are talking about. I'd start with buying four new ones and starting there. They are only about $25 per unit from Rock Auto.