W211 E500 ESM failure

[tomw]

As per my other post (W211 SBC pump failure - replacement in Herts? | Wheels, Tyres, Brakes & Suspension) my shift controller seems to have died. Classic symptoms of not going into reverse or park with my foot on the brake. iCarsoft reports P1856 and C404 errors.

Since I had a spare on the shelf, I changed the brake switch and no improvement, so I've pulled the selector unit itself out now.



What's my best option? Do I replace the entire thing? I don't want to buy a replacement off eBay and have it fail again in a month.

 

[IanW]

You have a couple of choices. When mine failed, an Internet search revealed at least one company that repaired & guaranteed them (BBA-Reman?? ECUTesting??).
I stripped mine down, re-soldered the phototransistor position switches & manually re-calibrated it using my iCarsoft - adjusting the position of the rotating sensor module so that the electronics detected the correct position of P-N-R-D. I think I got lucky, it's been fine since.
EPC/WIS shows this as being a theft coded part, but at least on 2005 CLKs it isn't.

If you're happy to have the car off the road for a week or so, then sending the unit away for repair is probably easiest.

Ian.

 

[tomw]

Thanks Ian. I've just found ecutesting too. Given my soldering skills I think I may be better off sending it to them. Not too happy about the car being laid up for a week or so (having only had it back for 2 days after my SBC failure) but I don't think I've got much choice really. Bloody cars.

PS will it be OK to leave it with the battery disconnected? Car's unlocked and parked in my garage

 

[Lenny63]

I got mine repaired by a local company, however my Brake Hold function doesn't work anymore on my s211 and there is slight play in the selector shaft...i should've went back but to be honest it was a pain to remove and reinstall so I just live with it

 

[E55BOF]

PS will it be OK to leave it with the battery disconnected? Car's unlocked and parked in my garage

It should be, but to be sure, put a trickle charger on the battery every three or four days if there's a risk of it going flat.

 

[tomw]

I got mine repaired by a local company, however my Brake Hold function doesn't work anymore on my s211 and there is slight play in the selector shaft...i should've went back but to be honest it was a pain to remove and reinstall so I just live with it

Interesting! Yes, getting it out wasn't much fun although the only bit I found genuinely annoying was getting that C clip off the linkage. I think I'll need to buy a new one when I come to reinstall it...

It should be, but to be sure, put a trickle charger on the battery every three or four days if there's a risk of it going flat.

I think the battery itself will be fine, I'm more concerned about the car losing its memory if it doesn't have power for a while (I had a Porsche that forgot it had heated seats after a battery change without hooking the car up to an external power source(!) ). I guess the aux battery takes care of some / all of that?

 

[E55BOF]

The (large) auxiliary battery is in fact the main battery, and yes, it powers almost everything. The starter battery is the small one under the bonnet, and all it does is provide extra urge if the large battery is low on power, and power the SBC if the rest of the electrics go tits-up.

I suspect the MB computer is dyslexic. If you buy a new large battery from MB for your E500, it will be labelled 'starter battery'...

 

[tomw]

I like to follow up on these threads in case anyone comes across them when searching in the future.

I received my shift module back from ECU Testing first thing this morning which was a pretty good turnaround time as they received it on Monday and sent it back last night, so 3 working days to repair it.

I was worried about re-installing the shift linkage as I'd also bought new bushes and a C clip but actually that was really easy once I figured out the best way to get my hand into the transmission hole to fit the clip. Tip: move the ashtray as far upwards as you can then reach into the transmission hole from the front of the selector module, while holding the module as high up as you can - the clip slips on very easily like this.

All back together, scanned and cleared historic codes with iCarsoft then a short test drive later all seems well. My SBC Hold works too. So far impressed with ECU Testing. Let's hope the repair lasts.