Starting problems

[antijam]

My SLK320 has been laid up for more than a year and now won't start. Initially it restarted on the first turn of the key but has gradually become more difficult. Some mornings it would not start and other times it would without problem. Turning the key now displays a full complement of dash errors and the shift is locked in Park but the starter is not engaged - there is not even a click from the solenoid.

One obvious culprit could be the K40 relay, and I have removed, disassembled and inspected this.





I have checked the fuses, cleaned the relay contacts and there don't appear to be any dry or damaged solder joints and I'm wondering if there are any simple tests using a multi-meter that can be done to check functionality? Any help would be appreciated.

 

[Wearsafoxhat]

Hi,

You seem to be very competent and I guess that you have checked that the battery is in good condition.
It could be a loose, corroded earth contact as another possibility.
The only test I can think for the rely is to check the circuits with an ohmmeter for continuity. Could possibly apply 12v to each relay coil and test the other “switched” circuit.


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[antijam]

Hi,
You seem to be very competent and I guess that you have checked that the battery is in good condition.
It could be a loose, corroded earth contact as another possibility.
The only test I can think for the rely is to check the circuits with an ohmmeter for continuity. Could possibly apply 12v to each relay coil and test the other “switched” circuit.

Battery is fine and all the electrics other than starting are good. Thanks for your suggestion.

 

[antijam]

An update. Despite my inspection and rudimentary testing of the K40 relay finding no problems I decided replacing it was worth a punt. It's probably the most likely source of the range of problems I was experiencing. Bought a new module from my local MB dealer (part No. A 170 545 03 05) for £168 and after swapping out the old one the car started on the first turn of the key.

Possibly a relatively expensive risk since I had no firm diagnosis, but since the car is not Taxed, Insured or MoT'd it worked out cheaper than getting it transported to and from a garage with suitable expertise and having them replace the same module and charging me three times as much.

I'm well pleased.