2007 MCS R56, N14:

• 80,000 miles
• No leaks
• Son drives it 10-15 miles a day to school and back
• New serpentine belt and water pump 12/3/2021
• New timing chain (and deleted adaptations) 3/19/2022

Last week I had a 'no spark, no start' situation. Car lost power and died while driving. P163x error codes (voltage monitoring control module communication error) led me to look for an electrical problem. I tested all fuses and relays under the hood and in the cabin by the passenger's feet. I unplugged all cables to both fuse boxes to check for burns, breaks, or water and found nothing. I did drop voltage tests with a digital multimeter and ground/power tests with a light probe and no findings. After all this, I still couldn't find a fix. Still 'no spark, no start'. I did have compression and fuel this entire time. I'm posting a video of some of the noises I was hearing while doing my voltage drop tests and fuse/relay testing. The relay works.... it's the K6300 position that is causing the relay to click.

After two days of letting it just sit there, I went back out and tried starting the car. It started right up. No more relay clicking like in the video. However, there is now no power steering. I started and stopped the car several times without issue. I've driven down the block and back 5 times and still no power steering. I have the Foxwell NT510 and used that to delete adaptations with no results. I also have no power steering fault codes or icons.

I'm at end of job here and don't even know where to look next. What are your thoughts?

Again, this video is from a couple of days ago and the K6300 port is no longer clicking like this. My only issue now is power steering. I post this video in case it lends itself to an underlying problem that I don't know how to diagnose.

 

@wsdivall

Hi,

Looking at my Bentley Publishing service manual, the power steering system is controlled by Electromechanical Power Steering(EPS) control module which is located right on top of the steering rack and it is in tandem with the DME. First check the "SPORT" button right by the shifter. Does it turn on when depressed? Next unplug the wiring harness from the EPS control module and see if there are any corrosions at the terminals. If there is, then you know water condensation is getting into the terminals. Simply clean those corrosions by using contact cleaner and put some di-electric grease to prevent any future corrosions.

Hope this helps

 

Thanks for pointing me in the right direction. After reading your recommendations and referencing the Bentley Service Manual we have fixed the problem... for now. The light came on in 'sport' mode. Check. I then unplugged the harness from the EPS control module. I didn't see any indication of burning or water. Frustrated, I plugged it back in and decided to try driving the car again. It started right up and drove like normal. Everything works. No more power steering problems. No more rapid relay clicking in the fuse box under the hood.

Other than unplugging everything, checking fuses/relays, and checking voltage drops, I'm not really sure what ended up fixing the car... which is unfortunate because I fear my car is going to die in the middle of driving it again. I think I can now appreciate the phrase 'gremlin in my mini'.

Thanks for your help.

 

@wsdivall

Sometimes unplugging wiring harnesses fixes most problems when giving terminals a good reseat and gives you an opportunity to inspect the condition of those terminals while you’re in there.