S320 CDI won't turn over cooling fan on full

[bicepius]

Hi, I wonder if Anyone can help me with this.

I was driving the car yesterday and everything seemed normal and then suddenly the engine warning light came on and the car just died.

Thankfully it happened as I was turning into my road, the car was pushed home

The symptoms now are if I put the key in and turn to pos 2 the only lights which come on are ABS and a red triangle with a car in the middle, (no glow plug light, or engine light etc), I can NOT hear the fuel pump and the engine Cooling fan starts and runs at full speed and is quite loud, I turn the key to start and nothing happens no crank, just silence.

I went through most of the obvious fuses and cant see anything blown.

I connected it to my carsoft v12 diag kit and ibm t30 laptop I have, there seems to be no communication with 'ME' which is the engine control unit I am guessing? I have successfully used carsoft in the past on this car to find codes. I have checked the ECU connectors for corrosion, clean as a whistle.

I keep all my drain plugs clear because I know that water Ingres is a problem on this car.

My past experience with water problems in electrics is you get intermittent problems but this happened suddenly.

Does anyone know what powers the ecu?

Thanks.

 

[E270 Owner]

Welcome to the forum


Failure to communicate with an ECU can be a can bus fault as well as a failure of the unit as well.

With MB Star you can diagnose the canbus system for errors,
sometimes the distribution box under the passenger foot well needs replacing or resetting
to allow the canbus system to send information around the vehicle again.

 

[memercdriver]

sorry to hi jack, but where can I find info on the "star" diagnostic kit??

help and advise greatly appreciated

 

[nb_racing]

Possibly dead control unit. The fan going full chat is a fail safe to stop the engine over heating. I recommend going to a reputable Merc specialist and get some proper diagnosis.

 

[bicepius]

Possibly dead control unit. The fan going full chat is a fail safe to stop the engine over heating. I recommend going to a reputable Merc specialist and get some proper diagnosis.

Hi thanks for the reply

I put a multi-meter on the ecu plugs, it was reading just under 6v with ign on so I am guessing the ecu is receiving power, which might rule out the sam unit.
I am going to drive to ecu doctor in Plymouth near me with the unit and get them to test it for £35 which is worth it to rule it out.

 

[bicepius]

Welcome to the forum


Failure to communicate with an ECU can be a can bus fault as well as a failure of the unit as well.

With MB Star you can diagnose the canbus system for errors,
sometimes the distribution box under the passenger foot well needs replacing or resetting
to allow the canbus system to send information around the vehicle again.

Thanks..

I did check the can-bus for corroded/loose connections. The thing is when I unplug the can bus the key in the ign does not turn at all, but if I unplug the ecu I get exactly the same symptoms, which may point towards the ecu.

 

[E270 Owner]

Thanks..

I did check the can-bus for corroded/loose connections. The thing is when I unplug the can bus the key in the ign does not turn at all, but if I unplug the ecu I get exactly the same symptoms, which may point towards the ecu.

A session on MB Star is recommended

 

[design guru]

I recently changed the water pump on a w202 C240 and the engine temperature sensor which measure the heat of the engine tells the ECU when to activate the main fan to cool the engine was damaged and caused the fan to run at full speed. I disconnected the main fan so the car could be used in the mean time whilst I waited to get the part but this still caused a backup feature to cut the car out. In the end I bought the part for £6 from ECP and it worked perfectly.

Its a very small part and looks like a bolt which is screwed in to the engine block or just pushed in a held with a clip. Its worth checking this.

 

[bicepius]

I recently changed the water pump on a w202 C240 and the engine temperature sensor which measure the heat of the engine tells the ECU when to activate the main fan to cool the engine was damaged and caused the fan to run at full speed. I disconnected the main fan so the car could be used in the mean time whilst I waited to get the part but this still caused a backup feature to cut the car out. In the end I bought the part for £6 from ECP and it worked perfectly.

Its a very small part and looks like a bolt which is screwed in to the engine block or just pushed in a held with a clip. Its worth checking this.

A session on MB Star is recommended

Thanks for the help guys..

Just to give an update in case someone else is going through the same symptoms. It was a bad ECU!,

I sent the ECU off to ecu doctor, they copied the data over to a good unit, got it back plugged it in, ignition on, glow plug light came on CAR STARTED!. Took it for a drive: flawless.

Star is great to have as an aid(I will get it soon) but if you an idiot like my local merc indie happens to be then it becomes useless. 10+ problems I have sorted on a modern merc without it.