I'd say that between all of us here if we can break it, we can probably fix it too!

Glad it worked for ya!

 

I parked my Crossfire last week, and went to start it, the lights came on on the dash, fan came on, but no starter working. Jumped the starter from underneath and the starter is fine, cranks good. Will not start. What could be my issue? Almost seems like the key transponder is not working. Please advise, anybody?

 

Man, this is an epidemic!! I too got the mystery no start today. I didn't pull the RCM to check the soldering points (after all of the reading, I'm confident that I don't need to).

Anyone know where I can order a new RCM online?

 

Sorry, but that does not make sense.
Do you really mean a CPS and not a RCM?

 

Relay Control Module

 

Is that what RCM stands for? I never knew.
You have not looked at the RCM, as there is no need to.
Even though the soldering or contacts may be bad, and could be fixed.
But you want to buy a new RCM which will have the same weak soldering?
What am I missing here?

 

What are you missing? The point.

I asked for help, not a hard time. Just as I helped you last month when you were trying to confirm the part number for your K&N filters.

So if you aren't going to help, save your sarcasm and wise cracks for another thread. I almost got stranded today because of the "no start" problem and I'm in no mood for jokes. I'm very much aware that it can be soldered and I'm looking at both options.

Now, can someone actually help me locate the part online?

 

Easy there Tom!
I was confused too after reading your post. I'm sure yer a bit upset, we just wanta help git ya back on the road!

The part number is listed here on the site (gotta search).
I have a loaner RCM that will get you back on the road.
Send me your RCM and I'll send you the loaner. You keep the repaired loaner, I fix your RCM and use it as the next loaner.
Only $10! What a deal!
A new RCM is gonna cost you $200+ I believe.

If you do buy a new RCM I/we would sure like to have your old RCM as a loaner for the forum members.

Here to help!

The Crossfire Forum Family!

 

Here. Found one for ya. LINKY

Let us know what you do to get it running again.

Now fix that XF!

 

Well I'm with 180, I missed the point also I guess. To not take tighed1's most generous offer to us of $10. for a resoldered RCM is just a little hard to understand. Even if it turns out to be the CPS or something else, It is still a preventive maintenance thing, given the number of folks that have had this same problem. I thank you for your post though because it has brought it more to my attention that I need to resolder or swap out my RCM for the loaner also so I don't get stranded, because I wouldn't be in the mood for jokes then either.

 

Speakin' of Loaner.

Want to send out a BIG Thanks to blackwellnorfolk (Dwayne) we now have a second Loaner RCM!
Sweeeeeeeeeeet!

 

I can send both mine to you at once for the repair now....lol...

 

Thank you to tighed1 and dinasrt for the advice and kind words. I did locate an RCM locally and will pull the current one today to check for defects. Luckily we do have another car, so I'll be okay until the RCM arrives. I was supposed to visit my parents yesterday and didn't go by chance. Really glad I didn't as I would have been stuck there wondering what the problem was.

This is by far the most helpful car forum I have ever been a part of. You guys rock.

 

If you get a new RCM send it with old one to tighed1. You might as well get it repaired before you install it as they all seem to have the same problem to a greater or lesser extent.
I have two and they both showed signs of failure.

 

Not the best photographer, but I pulled the RCM and took pics. What's the diagnosis?







I bought this car last year from a dealer in Virginia Beach and had it transferred to MD for sale. When I opened the RCM just now I could see traces of what I believe was salt inside the case. Not a lot, but enough that it could have slowly corroded the board for who knows how long.

 

Though not clear I can see that the joints in the last photo (the known bad area) are bad.
Simply hit them with a hot iron and add a little bit of solder and you should be good.

Don't know if I mentioned it but at some point Mercedes changed the part number on the RCM. Think I read somewhere that it was related to a recall. Maybe they have addressed the problem with the newer part?

 

I'll take pictures of the new RCM when it arrives. It was ordered under the new part number.

 

My car would not start, I turned the key on, all the lights came on in the dash, radio, etc. There is a black box under the hood on the passenger side. Open it up, you will see a fuse box with 1 big fuse and some small ones. Bang on the side of this fuse box, while someone else attempts to start the car. This is what I did, the car started, but as soon as I moved the box it would die. I repeated this several times and came to the conclusion it was the fuse box. A local wrecking yard wanted to rip me off for $250 for a used one. Mercedes Benz retail at the dealer is about $200 + tax. I found a Mercedes Benz (independent) repair place that could get me the box from Mercedes for $184. He got it from the same dealer that quoted me $200. I replaced it and my car now starts. The whole experience has left a bad taste in my mouth. I am selling the car, it was previously salvaged, it is a convertible in nice shape with 96K. $8,500. Good luck with your car hopes this helps. Anyone that is interested in the car can e-mail me. I'm in Southern California.

 

The part that is used on all Crossfires is the Mercedes part #A170 545 03 05.
The part mentioned in Mercedes forums with the same problem was part #A210 540 00 72.
The problem as I see it is caused by 'cold joints'. That is when the parts or one or more parts being soldered do not get hot enough for the solder to adhere.
In our case the terminals that are soldered are the ends of a buss bar, this buss bar is copper and having a substantial mass in relation to the PC board loses a lot of heat by conduction through to the large copper mass on the other side of the board. Heat applied to the joint will heat up the board enough, which is only a thin copper sheet, but heat applied to the terminal itself will have the heat rapidly wicked away so that it is never becomes hot enough even though the board allows solder to run around the the terminal.
The 'crack' is not due to vibration or heat but due to the cold terminal when the solder was applied. Such joints will look different depending on how much heat was applied, they could look nearly perfect or the flaw is very obvious when both terminal and board were not hot enough and the solder never really was molten.
Only use solders and fluxes suitable for electronics, that bit of solder you used to solder copper pipes in your basement is no good. Solders are molten at temperatures that vary by 100deg F. You want to use the low melting point grade, 360deg F (60/40) not 460deg F.(40/60).

 

typically that lower temp solder is leaded solder.... MOST electronics are now made with 'lead free' solder..which has the higher melting point.. IF the PCBA is made with lead free it is not a good plan to just add leaded solder to it.... different temps mean different reactions and mixing isnt uniform...
The lead free thing started as a EU thing and started big here around 2006 when EU started objecting to leaded boards coming over... they had already switched to lead free of course.

DJ, have you looked to see if the PCBA is labeled 'lead free' or not??