W204 strange behaviour

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Clem dog

New Member
Joined
Nov 10, 2014
Messages
4
Location
Northern Ireland
Car
C270cdi w203
Hi guys, I have a 2009 w204 C250 cdi that’s been giving me some headaches recently. It started on a motorway drive where the dash began bringing on the esp warning light and flashing a list of faults.
ESP/abs unavailable
ESP systemunavailable
Run flat system unavailable
Speedtronic cruise control unavailable
Presafe unavailable

All while the dash seemed to be tuning on and off with the brake warning light flashing.
It seems to not want to hold on to a gear and revs as if the transmission is slipping,
The PAS isn’t working while this is happening.
The main beam headlights flash on and off
The engine pre heat light is flashing on and off
This can be a combination of any or all of the above.
The dash ticks and the needles bounce a little after the car is turned off.

But the worst problem by far is that once the engine is stopped, it can sometimes (most of the time when this is happening) fail to restart, it won’t even turn over.
Most of the time, but not all, pulling a battery terminal for a few hours will allow the car to restart. Sometimes it seems to “fix” itself for a bit, but soon returns to form.

This began as being quite intermittent but has gotten progressively worse, have left me stranded without a car now for a few days as I have zero trust that when I get where I am going that the car will restart and get me home.

The MB specialist I see has tried a different SAM, a new EIS, a new ESL, checked earths and wiring, a new battery and the codes have all pointed to can communication errors.

It was just annoying aether start but now I’m thinking of taking the wife’s car to the shop for a box of beau peep and a gallon of petrol 🤬

Thanks for reading this far to those who have and if anyone has any light to shed, I’d be grateful. I couldn’t find anything in the search.
Mods, if this has been asked before or contravenes any rules feel free to deal appropriately 🙂

I have a short video of the dash doing it’s thing and I’ll post it from my phone soon.
 
Hi and welcome.
Sounds like a major bad connection to me, battery connection's at both ends of leads, fuse box power, starter, alternator, could even be ignition switch. Doesn't sound like ecu or anything like that so don't go chucking new stuff at it, start with the basics, check every major connection at both ends and go from there. Best of luck.
 
Hi and welcome.
Sounds like a major bad connection to me, battery connection's at both ends of leads, fuse box power, starter, alternator, could even be ignition switch. Doesn't sound like ecu or anything like that so don't go chucking new stuff at it, start with the basics, check every major connection at both ends and go from there. Best of luck.
Hi Tony, thanks for your reply. The car has already had a new ignition switch so I'll try and get the car into the shed and start checking connections. Would it be best to start checking earth connections first?
I noticed my video hasn't uploaded either 🤷‍♂️
 
Does the 204 have the same alarm sounder as the 203 (and many other MB's ) ? . If so just unplug this first , see what happens. If nothing changes get the codes read.

Unlikely for all of these codes to be real so post #2 sounds like a good call.

But cheapest 'try' is unplugging the alarm sender.
 
Does the 204 have the same alarm sounder as the 203 (and many other MB's ) ? . If so just unplug this first , see what happens. If nothing changes get the codes read.

Unlikely for all of these codes to be real so post #2 sounds like a good call.

But cheapest 'try' is unplugging the alarm sender.
Thanks Pete, where is the sounder under the bonnet in these cars?
 
Behind the front left wheel arch , behind the liner , easy peasy . lot's of links on internet. It has it's own batteries and when the unit fails/rot's it can send spurious voltage back into the car.

Only a very small chance it could be the cause of your woe's , but an easy thing to eliminate from your fault finding.
 
Another possible culprit is water ingress into electric wiring, or mouse damage to wiring looms - they like to chew on the plastic insulation.
 
Hi again, you mention it has had a new ignition switch, look there first. Try cycling it a few times and give the key a rattle, give it a knock or two while the engine is running. Hope you find the problem soon, keep us posted we like a good result.
 

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