Date registered: Jan 2008
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SLK Indicator lights staying on - Possible fix
1999 SLK 230 (RHD UK car )
I searched this forum to help me fix the indicators which were staying on on.
Got lots of help and was able to eventually sort out a fix which may be useful to other folks.
The fault was in the mulitfunction relay unit - part num 170-820-09-26. (This is a plus £500 unit to replace).
I managed to fix the fault without needing to buy a new one.
One of the relays was sticking due to pitting caused by general wear. A rub with some emery paper got it freed up.
Here is a guide for anyone else facing this. some pics are attached.
The relay is in the big relay box under the bonnet next to the battery. (It looks like it may be a filter unit for the aircon)
Lid on the box has 4 screws holding it on.
The relay unit in question is the one next to the battery (on RHD car)
Now - Remove the plug nearest to the front of the car - you will need to unlock it by sliding the grey toward the front of the car.
There is a metal handle thing at this end of the unit, pull it upwards and it will release the rest of the plugs.
With a bit of wiggling you can now remove the unit from the box.
Unscrew the 5 star screws holding the lid on.
You will see 3 gold coloured relays , the one that flashers the indicators is the one furthest away from the edge of the box. (If you hold the unit with the connnectors at the top, it is the one on the far right.
On mine this relay was sticking when closed.
I used a bit of folded emery paper to clean the contacts which stopped it sticking.
And in true workshop manual speak - reassembly is a reversal of the above.
This may not work for all faults with these units, but it is worth a try.