nlinesk8s

I have WIS, and this should be easy. I can find the Cooling section, with all the mechanical directions. But if I try and search for circuit diagrams in the cooling section, it comes up empty. I can find the circuit diagram that shows the temp sensor to the ECM, but i can't find the diagram for ECM to cooling fan.

I've searched the list of diagrams. No luck. I've tried running text searches for Fan (370 hits) and Cooling Fan (0 hits).

I need to check the correct pin from the ECM to the fan, and can't do that without finding the diagram showing the connection.

Any help appreciated navigating this particular haystack for a pin. BTW, the car is a C230 kompressor coupe, 2003, 203.740.

Plutoe

Try this. Go back to options and check English not American English for 1 and 2 choice with German as 3
Now with your VIN wada you get

nlinesk8s

I did that. Still couldn't get a related diagram. I finally went back to the list of all circuits and found the efi control. Looks like green/blue to pin 16. The other small wire looks like it goes to the front sam relay, not sure why. Guess I could check the relay too. Thanks!

Russell Ormerod

There is no relay! Ecu outputs pwm signal and sam supplies ignition power. Look in group 7 it's all there! If you connect xentry you would be able to test it all without having to find any diagram

nlinesk8s

I asked about the relay, as it looks like the power to the switch at the fan comes through relay 17, which I thought odd. I checked pin 16 for continuity to pin 4 at the fan plug, and it was ok. So I'm pretty sure at this point the fan needs replacing. Group 7 (mixture) wasn't the first place I would have looked. BTW, circuit is pe07.61-p-2101-97fg (2003 c230 sport coupe, m271 engine)

Russell Ormerod

What you mean relay 17? Mercedes doesn't label relays with numbers they always start with a K letter. So I have no clue what you mean. Check for fault codes first. Fan needs 2 power supplies and signal from ecu. Actually just unplug ecu and switch ign on and the fan should start to run at max. Simple

nlinesk8s

take a look at the diagram. The red/black wire goes into what looks like a relay marked 17. It really doesn't matter, but I was curious.

nlinesk8s

Just a follow up on all this: I pulled the fan using instructions from internet videos. The instructions in the WIS were missing about everything critical. There's a short wiring harness going from the plug on the bottom of the fan to the control on the side of the fan. I don't think you can get to it until you pull the fan. There was obvious corrosion on the green/blue wire. Once cleaned and reinstalled, everything was fine. So if you order a fan for a replacement, check that connection first.

nlinesk8s

or it might just be a plug; my circuit reading skills are rudimentary

Russell Ormerod

Correct.. wis will only show until the fan plug. But corrosion on the signal wire will definitely cause an issue. They love to get water in them