2007 ML63 Electrical & Reverse Gear Issues

[AndySML45]

I have a really frustrating issue with this car. It's done 110k miles and the engine is fine. But I get random ESP failure warnings come up, which clear with a switch off and on again. But the real issue seems to be bigger.

On random occasions I get a complete selection of issues occur at once. It mainly starts with being unable to select reverse gear. If I put it in drive or manual mode, it initially selects 6th or 7th gear and is clunky when I move down to1st gear (all while stationary). But I cannot get it into reverse. Eventually the ESP light comes on again. After 15-20 minutes of cursing, powering on and off, playing with gears and so on, it does this surge of a reset where all lights on the dashboard come on, and stay on, the power steering fails, the radio powers off and on etc, but I can then select reverse and drive away slowly. This happened today. After moving off, I pulled over again in a place I didn't need reverse, powered off and on again and all was fine. Everything back on and working again.

This has happened a few times and leaves no codes for the dealer to check. I've seen some of these issues around forums and possible fixes being the Aux battery needing replacing, the CAN bus being faulty, the Ignition being faulty. It also feels like a bad earth or but of damp causing the issues as the features that fail clearly still work, it's just the signalling that's the issue.

How on earth do I go about trying to investigate this? Is there an obvious series of steps to start with based on others experiences??

Thanks

Andy

 

[BlackC55]

You have all the signs of water ingress somewhere. There will be codes logged, you just have to know what to do with them.

Are your battery terminals tight? And the jump start point under the bonnet tight?

 

[AndySML45]

You have all the signs of water ingress somewhere. There will be codes logged, you just have to know what to do with them.

Are your battery terminals tight? And the jump start point under the bonnet tight?

Thanks for that. I'll take a look when it stops raining. See if it's wet under the bonnet.

 

[oldguy57]

I'd be taking it to an indie with Star who knows how to use it. As BlackC55 says if ESP light has been on codes will have been stored.

 

[DSM10000]

Thanks for that. I'll take a look when it stops raining. See if it's wet under the bonnet.

Check both front and rear SAM units for water ingress.

Water leaking through tail lamps etc is fairly common.

 

[Jigglyjohnson]

MLS suffers from the rear quarter glass leaking water into the o/s/r of the boot which in turn puts the rear sam under water. This then leads to water travelling through the floor channel and ending up putting the front Sam and aux battery under water after time corrosion sets in and weird and wonderful things start to happen. I'd say check these first but as advised already if warning lights are displayed the fault codes will be displayed and I'm guessing they will be with can communication with various modules. Keep us posted