Hello everyone. I picked up a R170 that had been sitting for a long time. It started and drove on Tues and when looking at the car I opened the passenger side door and the alarm went off so I closed it and alarm stopped after 5 mins. I went to get the keys (2 fobs) and called a tow. When I tried to start it it seemed to run for a few sec then die so they loaded it and hauled it to my house. Battery was very low so after charging I turn the key and nothing, no click, no fan running on high. Started with a 12.5 v battery but it quickly went to 11v. I am replacing today but the only light I do have is a warning light for the Immobilizer (start lock out misfuntion) . I will check the fuses for the immobilizer which I believe is 35 and 38 and install a new battery.

Someone mentioned with the battery pulled to touch the pos and neg together to reset. I have never dealt with this in the past. I ordered a new RCM unit but it will not be here till next week. I am no Wizard on these cars but if someone points me in the right direction I will do what it takes. I was out yesterday from the crack of Dawn until well past midnight. I have 2 original fobs that work the locks. You guys are all I have to turn to since I dont have a trustworthy shop in the area. I am into the car right and will do what is needed to get it on the road. Its not like I have time to go hunting for issues but I refuse to let it be yard art. So can you reset the Immobilizer after tripping the alarm and if so how. It looks like the CPS has been replaced but I will order another. Help NEEDED in Tn

Disclaimer : This is a 1999 SLK230 but please dont kick me out because we know this is the same car as the Crossie's I have owned.

 

Thanks for the move Mods. I am going with a new battery and checking fuses. Replace the Rcm (k40) on Tues and see what happens. Not so sure about touching the battery leads for 30 sec to reset it.

 

All is well, replaced the RCM/k40 and battery. replaced conductor plate and plug along with a full service. that plug is a bear! still in limp mode but the alternator was not charging so I have pulled it and ordered a regulator. I still can't get my scan tool to communicate with the TCM but will try again once I get the charging system up to par. You have to love these old cars because no one else will! Either way I will not let it beat me. Happy New Year! Over & Out !!

 

On a related no-start issue: My Crossfire would not start.

I found my problem to be a loose battery ground cable contact to the chassis. The car started right up when I re-attached the cable after cleaning the contact points at the chassis and the battery ground cable.

 

I will check that when the snow gets out of here. I have always used larger ground cables in the past and had a few left over from my XF's. I put a new Voltage Regulator in the Alternator thinking that had to be the issue of not charging, after getting a new never start battery. Still does not change when I start the car so I pulled the Alt back off, taking it in this week to be looked at. The car has been on jack stands for weeks now but the plug on the trans is not leaking so it has to be the alternator. Good news is I had it back off in 15 mins the 2nd time. I will figure it out soon. I hope . .

 

This should be in every 'electrical issue' thread / a crossfire mantra. Clean the battery ground at the chassis.
Along with Pull / Clean and Reseat each and every fuse.

 

WINNING! If you have charging issues read this! I found out that the small square black box in front of the heater valves on the passenger side is called a K56 and is a 125 fuse that links the alternator to the battery. That fusible link is solely triggered when an air bag is deployed and from what I have found they don't make the K56 anymore. I believe mine has been compromised which is why the car only had a handful of miles oner the last 5 years, just speculation on my part but I am installing a jumper while between the two terminals and I believe my charging issues are solved. Learn something new every day. Maybe when the system is working I will be able to clear the generic 7015 turbine speed sensor code, just maybe.

S I am connecting term 2 to term 3 with a jumper, am I not understanding the purpose of the 3 terminals? The R170 is the platform the XF is was built on and they have several things in common. That is why I am asking you guys for input. 30 days on this car, I need it to run and drive by sunset today.

 

Are you talking about a crossfire here? That .pdf is for a mercedes. If a crossfire, that square box near the duovalves is for three fuses. If your 'jumping' a fuse with a wire I would suggest you rethink that move. I know the crossfrie and an slk320 have a lot in common but either way I woulod not 'jumper' a fuse with a wire no matter what car it is located in. Just an FYI.


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Ive replaced quite a few alternator fusible links my day. I came to conclusion thru what I was told by the car owners in question that they end up failing most of the time from brilliant people changing the alternator and not disconnecting the battery first. The main power lead for the alternator comes in contact with a nice ground source and presto dead link or fuse.

 

Crash shut-off relay (k56 aka little black box) is what I believe has blown a fuse, I read that if you bring the 2 terms that have a second wire on them ( see pic) then the alternator will start charging. This is a safety devise that they did for two years. What is under a XF box? ,
I have checked all fuses and it all leads to this box but I am grabbing at straws. I do know I am in the wrong forum and will move on...but I trust this crowd; I can't say that so far for other forums and I have been reading way too much. Just trying to get the alternator to do its job and charge. battery is 12.7, I start the car and it does not change. New VR in alternator and it was checked at a shop. New BIG battery. Checked fuses. If you read the attachment its triggers by a air bag going off. I saw some paperwork where it had been in a body shop.

slk230k / R170 platform same car as the Crossfire. The way I understand it is under that box are fuses, that they are blown by the air bag going off. Is it called a K56 box on the XF? Does anyone know if you can replace the 125 fuses? I understood you can't therefore I need to bypass the blown fuse with a jumper and loose the safety feature My battery is new, alternator is rebuilt and the way I see it that box is stopping the alternator from charging my battery. . Thanks in advance, I am putting the alternator BACK on and will check back before running the jumper wire. Beautiful day in Tn and I am burning daylight!

"In normal operation the crash shut-off relay is actuated via the ignition lock (c. 15) ignition ON and connected ground (c. 31). This actuation connects the generator with the battery. If a malfunction occurs in the leads from c. 15 or c. 31 (e.g. discontinuity), the battery is not charged when the engine is running. The final result is complete failure of the vehicle electrical system due to the continuously decreasing electrical system voltage resulting from the battery not being charged. i A defect in the crash shut-off relay and therefore an interruption in the battery charging operation is not indicated to the driver by the charge indicator lamp"

 

Have you checked the voltage where the battery wire meets the alternator with the car not running? If that wire has power the isnt anything wrong with the fuse.

 

Ok after reading the pdf you linked its going to kill power to the alternator when the keys off too so checking that wire isnt going to help. This means you could have a bad fusible link OR a bad relay in there too. Im not familiar with how Mercedes does things but on my bmw's they use an explosive charge to disconnect one of the battery cable leads at the battery itself in the event of a wreck. Im guessing there is something similar to that inside that unit. If you havent had a wreck I would imagine the relay has gone bad that the ignition switch operates if the problem is inside that.

 

Ok I found this on another site.

Also that picture that just showed up in your earlier post cant have an ignition relay since the power is common on that bar from the battery so its powered all the time. So if you have power at that bus bar and the back of the alternator you dont have a connection issue.

 

sounds good, I do remember that most of the time the crash sensor is on the battery term, this is just inline. I just picked the car up and I did see it had been bumped and went to a body shop. Car fax does not show it, belts and alt back on but still on ramps. I will fire it up and check voltage at small wire on alternator which I am told is the small wire at the black box. I am in a 1999 slk230k now so this is the wiring PDF I found. I read somewhere that to correct this, you do a jumper between 2 terms in box and it charges. The said the 2 that had 2nd wires which I pointed at in pic. I would think a jumper between the battery and the alternator, what about you guys? I am really in the final hour so BIG thanks for the help, I get it charging I can park it and get on to my bikes that are late to be delivered. OCD sucks!

 

Measure resistance across the that last link that shows to be the alternator. If it has continuity from the bus bar side "where it bolts on" and the side coming out of the wire "the other side of the fuse thing" its not blown. Other method if the battery is connected then check for power on the fuse side that towards the wire aka away from the bolt side. If there is power there its not blown.

 

There should be 12 volts positive where the yellow box is. If there is with the battery connected then the fuse isnt blown.

 

Also if it is blown dont jumper it. Get a new fuse and replace it.

I'm not sure what Mercedes offers fuse wise but I know you can get an aftermarket car stereo amp fuse in that physical size and amp wise.

 

really, I thought it was no longer made and jumping it was my only option, all I loose is the safety side of it, nothing else. This was a 2 year thing that they found out was not needed. If a betting man, would you jump between the alt and the battery term? I am going to try and find the thread again but I am bringing it off ramps now, I can fix this after a beer.Going to do a jumper from hot battery to hot alternator until I can get a fuse. Most leave it this way, just like the old days.

 

The reason Im saying not to jumper it is if its blown there is a REASON its blown. Normally the reason is someone didnt disconnected the battery when changing out the alternator. But that is not always why.

If there is a bare spot in that wire somewhere from rats chewing it or something and you jumper it and that bare spot finds its way back to ground like it did when it blew the fuse in the first place you have eliminated the only fire protection you had. That wire will get red hot and become a long heating element melting the insulation off. Things just get nastier from there. It doesnt end well.

Also if something damages that wire in the future it will come back to bite you from taking that fuse out of the equation.

 

This is what you replace it with.



Mercedes inline replacement fuse.

But you need to get the right amperage one.