OMG I need help! I'm in Snowdonia for a weekend break and the problem has returned!

Early last week I had an issue that the engine would crank about half a turn and stop. The problem was intermittent and then permanent. No it's not the battery.

I replaced the starter motor as I found the solenoid wasn't working (checked it on the bench once removed). However it seems that might have been a symptom rather than the cause.

The problem can be seen here.
I'm now wondering if there is a poor connection to the solenoid, perhaps a bad wire or relay. An intermittent connection could cause a voltage spike in the solenoid coil and fried it.

Does anybody know where that white wire that goes to the solenoid traces back to?

Is there a relay that triggers the starter solenoid or does that line come from the ECU? I replaced R1 (K6300) in the engine bay but it hasn't helped.

I need more information!

 

i'm new to minis but it sounds very weak when the starter engages. Almost like it engages the starter, and voltage drops and the ecu pulls the start command? can you test the battery voltage? or do a load test on it?

Edit: i saw you posted that it wasn't the battery, i just wanted to make sure it was tested and isn't showing resting voltage as good and dropping out when under a load from a dead cell.
Also, If i remember correctly on my r56 (new to me 2 weeks ago so i may be wrong) has two positive leads coming to the battery connection. Is that crimp/connection good where the starter power lead connects to the battery terminal? and the same on the starter end?

Edit #2
I'm not sure if this will work or not, But if you have a long enough wire and a gator clip you could pull the factory signal wire off of the starter, gator clip the long wire to the signal connector on the starter and bump it off of the + on the battery to turn the engine over. I would assume that if the key was in it and it was in the ready to start mode the ECU would allow it to do so. And if for some reason you would touch it and it would do the exact same thing you would know it was a starter issue or amperage issue to the starter, and not computer related.

And i believe the relay is in the foot well fuse panel but i am not positive, i just remember hearing the click coming from there when i was tinkering around with my starting issue.

 

The white wire goes back to the JBE. If you suspect a bad connection, hot wire the starter to see if it turns like Mustang_gt_350 suggested.

 

Thanks for the advice.

The starter is brand new since I changed it last week along with the battery, so I know it works. Alternator also works, I can see the voltage go up when running.

Its got to be either a bad connection or the computer getting upset about something such as over current or who knows what. I have no errors on the code reader.

Can you provide any more info to help me find the other end of the solenoid wire? Like what plug or circuit point to test for continuity?

Is the JBE the circuitry to the side of the footwell behind the little secret door? I found a small bottle down there which was labelled 'Drink Me'.

 

Oh I tried manually connecting the starter motor when diagnosing the issue last week. It gave a yellow steering lock warning on the dash basically telling me to * off or it would immobilize the car.

 

Ok. So I guess that would narrow it down to a few things I can think of. Take this with the understanding I have only been around these cars for about 8ish hours. So i am by no means a mini master and a have a ton to learn about these cars.

the relay that signals the starter, as you asked about earlier is weak?

the starter isn't getting full power due to a main feed problem between the battery and the terminal connection on the starter( assuming the same monitors crank speed and shuts down the starting effort)

or based off the above statement of if the same does monitor the cranking speed whatever sensor it uses to read it isn't giving proper feedback?

this is a odd issue to have. I don't know what parameters the dme looks for before and during the starting process.. example, my 7.3 powerstroke looks for a minimum cranking rpm, minimum pressure from the high pressure oil pump that fires the injectors, and I believe a minimum voltage while cranking.

just a thought, have you tried a different key?

 

Is it a manual or automatic?

 

Firstly, my wife and I got home from Wales and enjoyed our holiday!

Yes I agree with your logic. I know the starter main power and ground connections are good, I checked them.

Sensor issues *I think* would produce errors I can see on the code reader.

The fact my previous starter solenoid was dead when I removed it means something killed it. Inductive coils can produce very high voltage spikes if suddenly disconnected with nowhere for the power to leak out (magnetic field is established with power applied and when disconnected the field collapses creating a current in the coil. With no path to dissipate current the voltage spikes until it arcs over the insulation.)

So I think the evidence points to a connection issue such as an arching relay or dry solder joint that 'spikes' the solenoid coil.

I'lldig in to the footwell electronics / fuse board and see what I find. If anyone has detailed info on what each relay and plug connection does, that would help a lot! Seems there are many permanently soldered relays in there.

 

Good luck with finding what the permanent relays do, it's hard enough to find what the marked relays do. At least that was my experience with the time I searched for wiring schematics. Looks like you time will be spent tracing circuits.

 

In this thread, someone kindly posted a link to some detailed wiring diagrams - https://www.northamericanmotoring.co...ml#post4412196

The relay for the starter solenoid is indeed inside the CAS module under the dashboard.

I'm going to try and get to it in order to check for dry solder joints and replace the relay.

Is it okay to disconnect and open the CAS module? Assuming I don't damage anything, will it simply plug back in the car and work?

 

An interesting update!

I went to the hassle of removing the top dashboard and getting at the CAS module.



Upper dashboard removed.


A slightly disjointed instruction on getting at the CAS can be found here http://support.rpmmotorsport.net/art...odule-location

That website also describes the problem I have quite well "CAS Module is defective due to Terminal 50 (Engine Turning over for half a second and quits)."

Upon removing the CAS and opening the enclosure I was greeted by a very obvious (bad) repair that had been done in the past!



Original bad CAS repair

That relay is the one responsible for triggering the starter solenoid. I can see a burn out track on the PCB running under the relay from a diode. This looks identical to an image I found for a BMW E90 owner with issues starting. Seems to be a common weak point. That diode (the black rectangle the wire gos to) is almost certainly there to provide a path to ground for 'back EMF' generated in the solenoid coil at the time power is disconnected. Seems the track on the PCB was not beefy enough to handle it. Another burnt track was going from that diode to a a number of resistors labelled '302', probably to sense output voltage, which were only connected indirectly via the thinner repair wire to the relay and back to the diode.

I removed the hot glue with great care, heating it up with my SMD hot air gun limited to 100c. The smaller diameter wire (upper one in image) came right off. It was only being held on to the contact by the glue. I think I found my intermittent issue!



Wire came free when glue removed. Dry looking solder joints.


So I have repaired the circuit more 'properly' and put it back in the car. It starts up just fine (thank god!). Now I need to see if it will keep working and the intermittent issue is gone.

I thought it interesting too, that the connector plugs are not soldered to the PCB! They have split pins which simply push in to the PCB holes. This must be for speed of assembly (possibly a way to mitigate vibration damage?). I checked a few photos on Google and others CAS modules are this way too. I would have soldered them in, but my iron doesn't have the heat capacity to solder the big ground pads. Worth saying I would have replaced the relay, but I could not find a suitable alternative. The same part number only turns up 12V versions, while this is 5V.




Finished repair. '302' resistors linked to diode via a thin wire. Diode linked to relay output via red wire.