Smart ForTwo (2005) Lighting Problem

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1 Feb 2011
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Location
Gloucestershire
Country
United Kingdom
Hi Everyone
Got a strange problem with the lighting on this Smart. With the ignition off all lights are off, and the switch on the stalk is inoperative, in that the side and tail lights do not come on with the switch in position 1. With the ignition on, all lights, (side/tail and headlamps on dipped beam) are on, but the stalk is totally inoperative. Main beam does not work, neither does the headlamp flash. The rear foglight which should be on with the stalk in position 3 does not work either. Unfortunately, finding a decent wiring diagram for this model is like searching for dodo's eggs. Has anyone come across this problem (which started all of a sudden), and what was the solution.

Thanks in advance
 
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Sounds like you need a new lighting stalk mate.....any signs of burning with the column shroud off - or even charred/ discoloured wiring in the same area?
John :)
 
Thanks, Burnerman. I will take the shroud off and have a look, but what intrigues me is that the lights did not come on with the ignition (unless switched on at the stalk) before this bizarre episode.
 
I would guess there's a fused contact or two within the switch but hey, it's only a guess Im afraid......these cars aren't exactly the favourite of Mercedes Benz technicians!
I'm only suspicious as the fault appeared without fiddling and warning, and I had similar problems with a Renault some time ago.
Be lucky
John :)
 
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I took the switch off and tested the contacts. All appears good. With the switch on the bench, the damned lights still come on with the ignition, and testing with a multimeter shows 0V on the red (perm live) wire to terminal 30 on the switch (ignition both on and off). There has to be a relay somewhere which has gone defective. Anyone know where I can get a wiring diagram?
 
After much internet trawling, it looks like all the control is in the SAM unit. I have conceded, and next Thursday the car is going into the local auto-electricians for diagnostics. I will let you know the outcome (provided that the cost hasn't killed me:D)
 
It turned out that the trailer socket wiring (done before I had the car) was shoddily done, and it had burned through causing one of the main fuses (apparently underneath the SAM unit, which has to be removed to replace it!!!!!!!) to blow. Then it was shorting, causing the lights to come on through some quirk in the SAM unit. It's working fine now, and under £200 to boot!
 
Hell that's a nightmare and no mistake.....its the sort of thing that wouldn't be found in a month of Sundays - and wouldn't occur if it wasn't for CanBus.
Well done you!
John :)
 
Thanks, John. I believe it is always worth sharing the result (for want of a better word). Someone might find it useful further down the line.
 
Appreciated!
I have concocted a device that uses LED's that I can plug into a trailer socket - it has a long lead that can reach into the cab as I work the various controls / switches or whatever. I thought it was pretty good but unfortunately if there's a resistance in the contacts between trailer socket and plug, the LED's still work but they don't take into account the current required to light the stop / tail bulbs.
John :)
 
You would be surprised how pokey that little 700cc turbo engine is! It'll keep up with much more "powerful" cars quite easily. TBH I have no idea what was towed behind it. The towbar was in situ when we bought the car. I would speculate that it was a small camping trailer or similar.
 
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