Mercedes Sprinter 313 SAM Unit Replacement Advice

[AlanDogg]

Hi Folks, I recently purchased a sprinter 313 (2011) which I purchased to convert into a camper, On removing wall boards I found some horrific after market wiring, I noticed one of the interior courtesy lights was flickering. I gave it a tap and the engine started turning over, along with heaters, wipers, water spray etc all coming on, I quickly removed the light fitting, and it changed nothing, I eventually was able to remove the live from the battery, by that time the SAM module was burnt out. I sourced another module from Holland and fitted it. Everything worked fine apart from the following errors.

​

NOTE: Before refitting the new SAM module, I removed all 3rd parts wiring including tow-bar to start from a clean sheet​

1. Side marker lamps.
2. SRS restraint system visit workshop.
3. ESP visit workshop.
4. Rear brake lamp.

I checked the wiring loom that runs from the back of the lights down the passenger side and connects to the SAM module. Removed all tape and found 3 wires melted together. I identified them as rear driver's side brake light (Red/Blk) rear passenger side brake light (Blk/Red) and top rear brake light (Yellow/Blk) I removed these full runs and replaced them and cleared number 4 fault (Rear Brake Lamp)

I checked the rest of this loom and all seems fine.

I'm a bit puzzled to why I'm getting the remaining 3 errors which are not clearing via OBD2. I can only assume, as these faults still exist?

1. Side marker lights
when I switch on the lights the marker lights all briefly flash twice then go through another 4x 10 secs cycle of this then go off completely, I assume there is a short or high resistance level being detected?

2.SRS fault
I did fit a new swivel seat that comes with the connector, but this error was thrown up after the SAM module was blown before the swivel seat was fitted. Tried 10ohm resistor bridging the connector, but it made no difference. ?

3 ESP
I believe it's something to do with the brake light error thrown up earlier, but may be wrong as not sure

SAM MODULE COMPARISON NOTE

After searching the internet i found the replacement SAM module but did notice a slight difference on Q code, mine being Q 002 and the new on Q001 everything else was the same including hardware and Firmware versions. I have listed a pic of both in case the issue is the difference between the two. When I purchased the replacement SAM module it came with a fuse box and relays, There was a staggered pin connection on the new fuse box that wouldn't allow the vehicle connector to connect to it including 2 extra pins, so I reverted to my original fuse box.

I would appreciate any help to guide me in the right direction to sort out and understand these issues.

Regards Alan

 

[M80]

I think you find the SRS code has latched and will take a reasonable diagnostic to reset it.

When the SAM sees a fault it can disconnect the end device, each cycle of the ignition it will have another go, see a fault and disconnect. Unless it's the DRL's I would have expected the SAM to illuminate the fog lights as an alternative to the side lights.
Anyway I would try new lamp's' in the side lights in case the SAM doesn't like their load.

The ESP could be any of a number of causes, wheels sensors, (I think) brake light switch. Really again you want a good diagnostic.

iCarsoft V2, or if you have other makes of car the CR Pro, has good feedback. I personally find the iCarsoft a bit restricted on the 639 so you may find the same. But it still has good purpose.

 

[M80]

Is it possible that trailer wiring has over loaded the SAM, and wiring to the trailer socket?
It should be fed through a tow relay. That is supplied from a dedicated fuse and so a trailer fault pops that and has no effect on the vehicle lighting.

 

[AlanDogg]

I have ordered new led side marker lights that are said to be fine with Mercedes so hopefully it will sort that issue, Also ordered Launch CRP129 OBD2 Scanner https://www.amazon.co.uk/LAUNCH-CRP...8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
If I doesn't work I will return it for one of the above. Tow bar was hacked into the existing wiring with broken interface, so removed the lot to make it safe. The ESP I found the brake switch above pedal was jammed so hopefully when I get OBD reader and reset fault cod it clears. Will le you know thanks

Many thanks for getting back to me so quickly

 

[AlanDogg]

Hi Again,
Got my OBD2 reader today and was able to reset SRS, so you where spot in with that It also showed issue with foot switch as you suggested along with side marker lights, still got 2 errors any ideas to where I should go from here? Thanks:

PS: I have enclosed diagnostics pics

 

[M80]

There are 2 contacts on the brake light switch, either could be duff.
But 1st check the switch is set correctly at the pedal, The system needs to see the changing state as the pedal is pressed. It's vaguely possible bending the carrier of it could sort it. Put a spacer on the plunger to be sure it's in, then press the pedal.
Faulty brake pedal switches aren't uncommon. They're inexpensive and easy to replace. Push the plastic tab and rotate,
I think there are 2 types. So worth removing to check prior to ordering.

Is the engine error light on?
MAF's (Mass Air Flow) have been cleaned, but I wouldn't hold out much hope.
Cheap after market jobs are considered to be a false economy.

For me, if it's not in limp mode, I would run it for a while, try another reset, and see if things improve.
I'm pretty sure there is a calibration of these on Star.

 

[M80]

I have experienced faults on sensors that were due to flared contacts.
If meter probes are pushed in to the female it can leave them flared open, with a resultant unreliable connection.

 

[AlanDogg]

Thanks again bud for getting back to me, your advice has been reassuring and much appreciated.

I have ordered a new switch for brake pedal as there was an issue with it previously, so makes sense to replace it as it's inexpensive.

MAF sensor fault, this issue only appeared after SAM unit failure. There is no engine light on at all, fault oinly comes up when running diagnostics, there is also a 2 message warning on dash, one being brake switch the other possibly MAF or Side Marker lights?

Will run diagnostics again once I receive brake switch and new marker lights.

Thanks again

 

[M80]

The MAF has no relationship with the SAM, it feeds directly to the ECU.
But you did previously suggest that the engine turned over from the interior light manipulation. I considered this to be a coincidence as the lights are direct from the SAM also.
But understanding what caused the engine to spin w/o using the ignition key would be interesting.

Since the van has been dabbled with during previous ownership it might be worth checking that the MAF is the correct one for it.
Look here, a useful tool for such things,

Mercedes > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes.

nemigaparts.com

 

[clarkmichigan55b]

This may be of help in changing your brake light switch. Florida Van man

 

[AlanDogg]

The MAF has no relationship with the SAM, it feeds directly to the ECU.
But you did previously suggest that the engine turned over from the interior light manipulation. I considered this to be a coincidence as the lights are direct from the SAM also.
But understanding what caused the engine to spin w/o using the ignition key would be interesting.

Since the van has been dabbled with during previous ownership it might be worth checking that the MAF is the correct one for it.
Look here, a useful tool for such things,

Mercedes > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes.

nemigaparts.com

 

[AlanDogg]

Hi,
Thanks again for your input, will checkout the MAF tomorrow. The wiring 100% shorted and blew the Sam module and caused engine to turn over. The MAF I believe has had an issue since purchasing the sprinter and only came to light via OBD diagnostics and as you suggest is not related to the short or SAM module. I'm going to purchase a new sensor also and hopefully it resolves that issue. Timing chain kit also on the agenda but just want to address these issues first so I can progress with the conversion will checkout the link (Thanks) and report back to base with results of MAF, Light Markers, and Brake Switch

 

[M80]

Feel free to ignore.
I'm assuming you have the om651 2,143cc engine.
Are there symptoms that suggest a timing chain issue?

A short rattle on cold start is the usual pointer to some action being beneficial, it isn't always a new chain.

 

[AlanDogg]

Feel free to ignore.
I'm assuming you have the om651 2,143cc engine.
Are there symptoms that suggest a timing chain issue?

A short rattle on cold start is the usual pointer to some action being beneficial, it isn't always a new chain.

Hi bud,
I never noticed any rattle from engine at startup, I will check tomorrow for sure to see if this is the case. I'm getting the timing chain replaced as a safety measure as there is no log to if and when it was last changed. It makes sense to get all these issues and preventative measures sorted now as I'm spending a fair bit off coin doing the conversion.

I really do appreciate everyone's input
Thank you all

 

[ajlsl600]

I am interested in the procedure for changing timing chain om651 just in case I still have mine when it needs doing. I far prefer to understand the story before fate presents the issue so any link to that I will print n add to my ml250 file, as I did with issues on Vdoz

 

[clarkmichigan55b]

This may be of interest if you have to do it.

 

[M80]

Personally I would wait for the start up rattle,
then I would replace the tensioner as the easier and cheaper fix.
If that didn't stop the rattle then I would be fitting a new chain.

While mine is supposedly good for 22k mile oil changes I'm intending to change each 15k in hope that the chain issue doesn't arise.

 

[AlanDogg]

Ordered new Bosch MAF due tomorrow, got brake switch today, will fit both tomorrow and run diagnostics to see where things are at will check for the death rattle at the same time.

Fingers crossed

 

[AlanDogg]

OK, So fitted new MAF and there is no change of fault. I ran diagnostics and cleared codes, but it still shows 2 errors. I will fit the brake switch later today but got a funny feeling it will be the same, and I'm leaning towards wiring issue (possibly melted wires there also) without a wiring diagram I'm more or less fault-finding in the dark, Is there a wiring diagram available?

On a positive note, there was no rattle upon start up, don't think it's in limp mode, but will need to run her to see if it is or if it clears the MAF fault. Any suggestions guys?

PS: Included link to diagnostics report below, for some reason diagnostics is saying its a 2002 Maybach model when its actually 2011 sprinter

http://aitus.golo365.com/Home/Repor...e59d2ge3b54nRDhTdTdnRLr/report_type/D/l/en-us

Again thanks for everyone help

 

[AlanDogg]

UPDATE!
Fitted brake switch and fault has cleared for brake

Inspection Report http://aitus.golo365.com/Home/Repor...5336cge3b54nRDh54Kw54OM/report_type/D/l/en-us