elphzwolf

Yeah... The mercedes dealership quoted a new EIS + an orange key + a new fob key at something around US$1200 + labor ... Anyway he picked apart the EIS... seems one of the chips was fried and he is currently reprogramming the replacement chip. Hope all goes well.

Russell Ormerod

good stuff let us know if it was repaird sucessfully and what chip exactly failed..
Thanks

Russell Ormerod

One more thing, has the eis also sorted out your temp gauge?

Glyn M Ruck

He confirms both gauges working in post #24

elphzwolf

Update: After 2 weeks of screwing around, I finally fixed the EIS with a used reprogrammed EIS (turns out the electronics guy burned mine out beyond repair while trying to fix it), got new keys etc... Got everything working EXCEPT THE TEMP GAUGE... When they hook up the ECU via ODBII, the temp readout never goes beyond 22 degrees celsius. They replaced the thermostat, and said that the temp sensor is attached to the thermostat itslf (funny cause according to the schematics I have, the coolant temp sensor B11/4 seems to be a separate entity)... They said they checked the lines and all was good and they say that the problem is in the ECU (and everything else working?)... The price of a new ECU at the certified service is somewhere in the ballpark of $1600US... So my questions are these:

1. Are the thermostat and the sensor two separate entities
2. Can anybody post photos of the location of the said sensor (B11/4)
3. Are there any implications of driving the car with no temp sensor
4. What are the odds I **** up the engine from overheating with a new thermostat and driving the car mostly in urban setting and never faster than 130/140 km/h

Thanks for any and every input.

elphzwolf

*bump*

Russell Ormerod

I was always Puzzled how your EIS "FIXED" your temp gauge as stated in your previous posts!

I am 99% percent sure your B11/4 coolant temp sensor is a loose part.
What engine is in your car 111 or 271?

first of all when you scan your engine ecu are there coolant temp sensor fault codes?

If the engine constantly runs at a 22 Deg signal it will run on the rich side which is not the best situation, but i doubt whether you will cause any serious damage uptil now.

the 22deg you read is that from the engine ecu or the Intrument cluster?

Russell Ormerod

send us a pic of the part they replaced. then we know what we talking about.....

Glyn M Ruck

Pleased you came back Russell. He has an OM611 diesel engine.

See 47 here for temp sensor. It clips into the thermostat housing.

Part number I have:

47 A 000 542 51 18 .SENDER UNIT
TEMPERATURE GAUGE SENDER UNIT 001

elphzwolf

The schematic Glyn posted is just right for the thermostat + temp sensor that was replaced. There are no temp sensor fault codes when connected via ODBII. The 22 degrees is the value I get from the ECU... Supposedly they checked the sender unit and it was ok. 2 things left to check, I guess: the line and the ME-SFI

Russell Ormerod

I doubt that the ecu is at fault, but you never know. firstly you need to do some checks. If you have a 611 engine your engine ecu is CDI2 Not ME.

Connect OBD scan tool
enter CDI2
Unplug B11/4 coolant sensor
Actual value should read -40 C

Short circuit the coolant plug using a wire bridge
cycle the ignition

Actual value should read 130 C

To test if your sensor is ok. refer to these values

10 Deg Celcius----4850-5000 ohms
20 Deg Celcius----2940-3240 ohms
30---------------1900-2100
40---------------1265-1395
50---------------855-945
60---------------590-650
70---------------420-460
80---------------305-335
90---------------220-240
100--------------160-180

Let us know your findings

elphzwolf

Will do, I'll post the results

elphzwolf

Update: Unpluged the sensor - 22 deg celsius. Shorted the line terminals - 22 deg celsius... Guess it's the ECU. Now is there a way to "reprogram" the ECU i.e. give it it's original firmware back in case it's just a software problem, or do I have to buy a new one?

Russell Ormerod

with the sensor unplugged. measure the voltage across the sensor plug.
then measure the voltage at each terminal with respect to ground.

One wire should be an earth output from the ecu the other should be around 5v that is the signal line.

i very much doubt weather its a software issue.
lets see what your voltage readings say before we condem the ecu!