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This suggestion goes back almost to the beginning of this forum. The two most common reasons for problem starting are failures of the RCM (relay control module) and the CPS (crank position sensor). It is recommendid to keep a spare of these two items in your trunk just in case. The RCM is plug and play and takes 5 minutes. The CPS requires a small ratchet, extension and an E8 female torx socket. It would be smart to keep these with you also. This can keep you from being stranded. If you ever need to replace the RCM, keep the old one and have it rebuilt by djtighe@hotmail.com and keep it as a spare. The correct email in tighed1@hotmail.com
This suggestion goes back almost to the beginning of this forum. The two most common reasons for problem starting are failures of the RCM (relay control module) and the CPS (crank position sensor). It is recommendid to keep a spare of these two items in your trunk just in case. The RCM is plug and play and takes 5 minutes. The CPS requires a small ratchet, extension and an E8 torx bit. It would be smart to keep these with you also. This can keep you from being stranded. If you ever need to replace the RCM, keep the old one and have it rebuilt by djtighe@hotmail.com and keep it as a spare.
You are correct, my miss statement. It is a female E8 torx socket. Thanks for the catch.
Yeah, thanks! I went out to my car later on and found my drive/extension/socket (with the NEW Bosch sensor) confirming it was a socket. Thanks for replying!
Yeah, and if you're gonna own one of these with Mercedes under the hood may as well get the whole Torx M/F set. I know I did. Note: To use this full set you're gonna need 1/4", 3/8" and 1/2" drives.
Had the RCM replaced in my 2005 LE in September 2018. Already went bad and now have to get another new one. Hope I get more than 3 years out of this next one
Do you remember what brand and where you bought it?
I was going to buy one for a spare and may want to avoid your problem.
Any recommendations out there?
Do you remember what brand and where you bought it?
I was going to buy one for a spare and may want to avoid your problem.
Any recommendations out there?
The new RCM was installed by my local Auto repair shop that specializes in foreign cars.
The RCM has a Mercedes Benz logo on it so I am assuming he purchased it through a reputable MB authorized parts store.
I am going to ask him where he purchased the new one he is installing so I can obtain a backup as well.
Once that one goes, I'll probably sell the beast.
Last edited by pjpalmeri; Nov 25, 2021 at 08:34 AM.
Note to new owners
Help me out here, isn't it a T-8 SOCKET? Didn't remember it being a T-8 bit. Oldtimers here??? 
Yeah, thanks! I went out to my car later on and found my drive/extension/socket (with the NEW Bosch sensor) confirming it was a socket. Thanks for replying! 
