Originally Posted by
1sweetride
Did you ever resolve the "no crank" issue?
I am having the same issue, and have followed your troubleshooting to the extent above. Starting to think it is the PCM. Connected my autell code reader and indicates no faults (for what that's worth). Also looks like I have a high current draw when the car is off Key out. Had a noise coming from under the windshield cowl, and removed a horn/siren type of device. Do you know what that component is?
When attempting to starting the car also noticed the fuel pump does not come on for its aprox. 3 to 5 second cycle in the Run position before selecting Start. Believe this is also a PCM function. Running out of options on this, so any help appreciated
Mine turned out to be the SKREEM had gone bad. I wasn't getting the the common "3 tries then nothing" like what has been reported, but after banging my head against the wall for about a year, I took a chance and had the SKREEM deleted by Precision ECU out of Chicago. The guys over at the Mercedes Swap Shop (MSS) will caution you against having this done by Precision ECU and suggest you have it done by them. I had my car for about 2 years after the delete and never had any problems. I sold my car in March of 2023 and the new owners is using it as a daily driver and it is working great last I heard.
The item under the cowl is the alarm siren and it's best to get it out of there like you did, if not the entire unit, at least the battery. There is an updated unit you can install, but I think it's kind of pricey.
If your fuel pump is not running when you turn the key, have you checked the RCM? Getting it rebuilt by DJ Tighe was the best $50 I spent on the car. I believe the fuel pump relay is on the RCM - there are pictures on the forum of what each relay does. When you turn your key to on (not start), does your radiator fan spin up to a high RPM after about a minute of it being on (or sooner)?