Unusual Intermittent Electrical Power Problems Mercedes Sprinter

 

Have you had issues with mysterious power interruption or gremlins, maybe with wipers, headlamps, radio, indicators and various other sections of the vehicles electrics? – well the common issue is the fuse box distribution module that lives beneath the steering column on a T1N Mercedes Sprinter.

Mercedes Sprinter Fuse Box

Mercedes Sprinter Fuse Box

This highly complex ‘box of tricks’ contains a matrix of brass interconnections, distributing power to many circuits through fuses and plug connections.  It also contains the integrated flasher control circuitry electronics for the indicators and intermittent wipers.  What usually happens is the board suffers corrosion, usually caused by a spilled drink or liquid that makes its way inside the steering column and starts the electrolytic corrosion process off.  Sugary drinks such as coke or a sweet tea or coffee will do nicely.  Of course on occasion its just damp and condensation that sets the whole bad connection scenario off, but for whatever reason this is the centre of all electrical connection to the vehicle and more often than not is the source of a catalogue of seemingly untraceable electrical faults.

Mercedes Sprinter Fuse Box 2

It is quite simple to remove and service / clean up although the Mercedes people would prefer to sell you another one at a princely sum.

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First start by removing the under wheel door flap that covers the fuses on the distribution panel.  Then remove the cowling that forms the lower part of the steering wheel column cover.  Two cross head screws at the top and a single 10mm nut at the base will remove the plastic cowling. Once removed undo the single 10mm fixings top and bottom, then flip up the protective disc and remove the large red power lead eyelet.  Make sure you tape this up as it remains at permanent +12 battery potential regardless of ignition position.

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Once the fixings are removed and the large wire is protected pull out the top of the board directly from the two connectors beneath the steering wheel.  Once this is out the board will pull down to allow you to remove the connectors behind.  Once all these are removed the unit can be lifted away from the column and inspected.

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You can see from the pictures where the problem lay with this unit, several of the brass spade connectors had started to corrode, there were easily cleaned up once the unit was split open.  This is done by simply removing  the three small relays and the bottom edge moulding first, then further undoing the 10mm brass nut and washer that holds the unit together on the main power pin.  (the same stud where the thick red cable connects)  Once this is removed the unit will allow the black plastic cover side to be removed.  This will facilitate the easy cleaning and inspection of the tags that connect with the molex loom connectors.

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You can see the level of corrosion on the terminals, that once cleaned, (Don’t forget the plug spades as well!) will allow good electrical connection to made between the two mating parts.  Once clean the unit can be reassembled and fitted back in pretty much the same way as it was removed.  Sometimes due to a weak moulding, the threaded insert in the column plastic fails, preventing the secure fastening of the fuse board at its top edge.  The best cure for this is to remove the insert with careful use of a screwdriver and prize it out, then using a strong tie-wrap as pictured to secure the whole assembly.

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You may find that some of the fuse carriers have also corroded on the visible side of the board, the unit can be further dismantled to reveal the internal components of the holders that can be cleaned in the same way as the rear connectors.  However the most common cause of problems will be in the multi-way connectors on the rear of the unit.  Do not forget to clean the relay tabs that lie beneath the unit before re-inserting the relays into position.  Test the electrics before fitting the cowling and you should be good to go !

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Have fun…

42 thoughts on “Unusual Intermittent Electrical Power Problems Mercedes Sprinter

  1. Have 616 2004 mod gone into limp mode .Has been put computer it said low boost pressure, but they tell me the trubo is stuffed .So how come when they clear all the codes it runs like a charm ,if the turbo had it why when they plugged it into computer it comes good .I drive trucks for a living as far as as i know a turbo either works or does not

    1. Hi Bill,
      As you have probably read there is a great deal that can cause the issues you have. With regard to the turbo itself, you are correct that it either spools and compresses or it does not, but there is a middle ground – does it produce enough boost to always be in the required load range (worn turbo) or is the actuating mechanism intermittent causing an occasional no boost condition that sets the vehicle into LHM. I am suprised in many ways that the performance returns only on a ‘code reset’ because normally the codes would be recorded and once the problem was rectified or had righted itself (if intermittent), then normal driving condition should be resumed without further intervention. Maybe that is a pointer to the problem?. Check the connections to the ECU for corrosion as water is known to get through the bulkhead grommet and run down the loom into the ECU connectors. If you see a problem here, clean up the contacts and connector blocks then prevent further water ingress. (Worth a look as I have been caught out with unusual gremlins caused by this fault before)

      Maybe I would also look to swapping out the MAP sensor in the induction pipework post turbo, or at least cleaning it with some carb spray to see if there is any improvement. This is a common device that fails regularly by reporting incorrect boost pressures to the ECU and it could just be the problem.
      Let me know how you get on.
      Best Regards and good luck
      Steve

  2. Hi steve
    Thanks for your help will check all those points. Put it on the computer again did not show any codes at all ,but was playing with the light switch and had moter running at 1800 revs when I turned the lights on revs dropped to 600/700 revs. I did not alter the revs turned the lights off and it went back to 1800 revs . My auto elec thinks this might be the problem. What do you think
    Regards Bill

  3. Thanks alot for this good informative problemsolver this saved my real big headache about why i can start if i touch the panel and stops if i dont haha 😀

  4. I was looking for electrical problem or sensor problem that would cause the car to rev but not move. Leading up to this is car reving but car is not moving as fast as the gas was given whene pedal was pushed down. Code finally came up after sitting with car running but not moving for 15 minutes….code was some letters then the word inactive..check owners manual. I can’t remember what tge letters were. Something like LYKE-LTE..not sure though. What could it be?

    1. Hi there Bonita,

      The display maybe reads ‘PRE-SAVE Inactive’ this indication combined with no drive, points to a transmission fault. You did not give an exact model, but if it has fitted a 722.901 auto-transmission (You can check this by calling an MB dealership with your VIN and asking for the code of gearbox fitted from their electronic parts catalogue EPC) it is most likely the hydraulic valve body internal to the gearbox that could be faulty. Other issues could be with control solenoids or electronic gear shifter but most likely the first listed.

      All the best
      Steve

    1. Hi Paul,
      Assuming these problems come and go it could be a poor earth somewhere. Look both under bonnet and in the right hand kick fuse panel of the car for star connected clusters of brown wires. Make sure they are all clean and tight with good continuity to the body. It sounds possibly as if the issue could be to do with the CAN communications being interrupted to body control modules that affect lighting, locking and other functions. Let me have a little more detail when you can as it may give a better clue as to what is happening. Model year would be good too.

      All the best
      Steve

  5. On acceleration in my sprinter 311cdi 2001 the engine splutters at the same time the temp gauge jumps in time with the splutter

    1. Hi Pete,
      I would be looking for an engine loom problem, either break or short in the section that runs to the ecu/bulkhead from under the inlet manifold over the top of the engine mount. Cut back the insulation jacket and have a look. Occasionally the injector loom that sits on top of the rocker cover wears through and creates an intermittent short. If any injector goes open or short momentarily the engine will stumble. A more permanent short or open circuit would stop it running altogether.
      Hope this helps.
      Steve

      Ps just check the condition of the star ground point behind the battery, 13mm nut with the battery negative and three other earths attached. Clean them all up. Also check importantly the engine earth braid strap, though usually this one would result in lazy or poor starter cranking.

  6. Hi Steve/Pete I had a very similar problem with my sprinter everything pointed to an electrical problem however I disconnected the instrument panel fuse under the drivers seat taking the temperature gauge out of the equasion & the engine splutter still occured indicating an underlying fuel issue. I replaced the fuel filter & the splutter has gone however there is still very slight occasional movement from the temperature gauge but not now affecting the engine.

    1. I would just like to update that my problem did return, after a lot of searching eventually a chafe was found in the coolant temperature wire & that was causing the problem.

  7. I have Mercedes Benz sprinter and the problem came two day before after washing the van it starts but after some time it just loosen the power and shut off i don’t what is it i keep pedaling the gas but it off’s itself

  8. Hi Steve

    On my 2010 vito intermittently the srs, handbrake and brake warning lights flash on then usually straight off all at the same time. Sometimes the srs light stays on for a few miles then clears itself. The strange thing is that the brakes and airbag are totally different components but all three lights always flash up at the same time.
    I’ve tried to find an earth problem with no luck.

    Do you have any ideas please?

    Thanks

    Paul

    1. Hi Steve

      Just to add I looked into this a couple of weeks ago and the symptoms sounded like something that’s part of each fuse box but I can’ remember what that’s called or find the info I found previously.

      Thanks

      Paul

  9. In a search for similar issues in my ’08 NCV3 I bumped into your very well done piece here. I’ve had electrical low voltage/start gremlins for 2 yrs. Replaced the Y cable, checked all the pos/ground conns, and finally ran into a Sprinter tech who said the fuse panels have had issues with poor connectors and corrosion as you pointed out so well on the T1. Is there a similar issue on my 2008 chassis? The fuse box seems to have been relocated to the side wall in the cab but I can’t find a clear path to release it and get to the back side to inspect it. If there’s a photo thread like you’ve done somewhere please link me to it or post how to get it out for inspection.
    Thanks for posting such a well done piece. Mike

  10. Handy article thank you – it’s been handy reading your thoughts and tips as we own a 2005 T1N/903 LWB sprinter we are converting into a camper.

    Some models of the T1N appear to have a 12v Live, 12V ignitiona nd earth hookup under the seat, sadly this wasn’t fitted to ours and appears to be a NAS spec only matter.

    Where is the best place to pickup an ignition switched 12v live?

    1. Hi Arnie,
      I think you would be better to have a look around the back of the ignition switch area behind the steering cowl. If you can’t find what you need on the switch back you will find it on the fuse board connections. Use a test meter to confirm what you are connecting to is exactly what you want.
      Regards
      Steve

  11. Hi Steve,

    You obviously know your stuff, so I am wondering if you can throw any light on an issue I have ( thats foxed my local MB dealer ) . 2003 Sprinter van MWB 313 Cdi.Sprint shift . The problem is the van starts fine , but when the brake pedal is depressed ,for the sprint shift to engage gear , it cuts out . This is intermittent, can go a few days with no problem , then it happens 4-5 times the next day ! I have replaced the pressure switch above the brake pedal , and brake bulbs , (the housings for these are relatively new ). Switching the ignition back on brings all the dashboard symbols to flash , beep, sometimes with “start error” message display coming up .Can have to try up to 6 or so more times , before I can finally depress brake pedal and get “A” displayed, to then drive off. Now the problem has developed further, as whilst driving and went to indicate , lifting the stalk caused both rev and petrol gauge to die and loss of power to the engine ! ( not ideal as I was trying to overtake ) Any help or pointers would be greatly appreciated !!
    Julien

    1. Hi Julien,
      This does sound like fuse box issues under the steering column. The stalk plugs into the top of the board so unsurprised moving this causes an issue. Remove the cowling and drop the fuse board as per the post, inspect clean and reseat all the power connections/multiplugs on the rear of the board. If you get the start error often either you have an issue with the key or key security module that lies behind the instrument cluster. If you have a spare key try using that for a day or two and see if things improve. The key chip may be faulty.

      Sorry I have not been a huge help, let me know how you get on.

      Regards Steve

  12. I have a problem with my Vito wipers, its a 2002 model, the vito wipers will work on slow but on any other setting it will just judder and then stop across the screen, I thought this was the motor so i changed the motor. But the problem is still there, someone suggested that it could be the relay, I dont even know where the relay is. Any help would be great. Thanks.

    1. Hi John,
      The circuit that controls the wipers and intermittent function is like the Sprinter and is integrated into the fuse board under the steering column in the W638 Vito. The Combination switch may be faulty and this is not uncommon as it gets a lot of stick, just make sure the plug section of the fuse board under the column is pushed home fully onto the combination switch contact plugs (these form part of the ‘handlebar’ indicators/lights/wipers control module). The rear of the fuse board has a few push in connectors some for the ignition others for the power distribution, make sure all these are clean and corrosion free. Change the control stalk next would be my suggestion, if no different then look towards an issue with the fuse power distribution board as described. Be 100 percent sure your replacement motor and wiper rack works as it should and connect 12v directly to it and make sure it functions as designed at all speeds.

      Hope that helps
      Steve

      Hope this helps

  13. hi steve ive got a merc sprinter 2009 311 2,1cdi , the horn,wipers and side lights wont work ive checked all fuses and all ok, if i put power to the side lights they do work so i think its not getting power , ive checked most of the earth points and wounderd weather you can help ..also the n/s/f dipped beam wont turn off (i have to unplug it at night)., thanks ben

    1. Hi Ben,
      There are a block of power fuses on the battery terminal see here, these have a habit of corroding it could be that one of the supplies here is all corroded. Break them all down one by one and clean the mating parts and see if that makes any difference. The fuse board under the dash near the bonnet release is generally quite hardy and it seems strange as you have lost a selection of items. This draws me to think that one of the brace of fused distributed power taps has either a blown fuse or corroded connection. Though unlikely (but worth checking out) it could be that you have an issue with the control stalk module, the arms either side of the steering wheel that action these functions – just worth an investigate if nothing else proves positive.
      Hope that helps

      Steve

  14. Thanks for yet another informative and helpful post. I recently had a problem which was presenting itself as a glow-plug issue – the ‘wait to start’/glow plug light on the dash wouldn’t go out, engine wouldn’t start. The problem was intermittent (80/20) but we were sometimes in some remote, extremely cold locations (e.g. Switzerland in February), so glow plugs seemed a reasonable diagnosis.
    Finally got to a MB dealer in Zurich who diagnosed the fuse box as the source of the problem. Easiest course of action since we were pushed for time and far from home was to replace it with a new one. Cost 300CHF – considering everything is so much more expensive in Switzerland, I had feared it would cost more. Being a dealership, they gave me the old box: I plan to use this thread to see if I can resurrect the old box.

  15. This is awesome Steve, thank you. I’m hoping it’s the source of my intermittent starting issues and occasional stalling while enroute in 2005 T1N. Do you have any suggestions for means of cleaning everything? Vinegar? Brass wheel on Dremel tool? Very much appreciated.

  16. Hi Steve

    I have a 2005 sprinter 311. The temp gauge just dropped down to zero then it jump back up and down. I have changed the temperature sensor and the thermostat and still the same problem. Do you think the fuse box can be my problem?

    Thanks

    1. Hi Daniel,
      It could be a short in the wiring or a broken conductor near the plug to the temp sensor on the stat housing. Have a close look in that area.
      Best
      Steve

  17. Hi Steve,

    The LED backlight on the odometer does not shut off after the vehicle is turned off. This (I think) has been causing the battery to drain when the van has been sitting for extended periods of time.

    Any advice on how to fix this?

    Thank you.

    – Harry

    1. Hi Harry, could be the ignition switch is faulty allowing current to pass to aux circuits when in off position or a door closure switch not making – this means the vehicle thinks a door is open and illuminates the odometer. You should be able to open a door and the milage display illuminates.
      Best Steve

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