Hoping someone can help point me in the right direction. I've been chasing what I think is a ground issue on my 2012 , manual transmission n18 for a few weeks.

Car began occasionally not cranking , then over a few weeks got worse and now its a struggle to get it started, where sometimes its no crank, others it sounds like it loses power mid crank.

I've chased down a few possibilities so far. I Replaced the engine-to-body ground strap and cleaned contact points, checked the footwell for signs of corrosion or water ( none found) , cleaned and reseated the 2 grounds ( i think the were grounds) under the fuse box in the engine bay, replaced the clutch safety switch, replace the starter relays in the engine bay fuse box , replaced the battery, inspected and cleaned the 2 stop/start fuses in the footwell, tried cleaning and wigglilng the start button, and cleaned the battery negative cables. Car still doesn't want to start up properly. When it has just flat out "no cranked", I jumpered the engine block to the shock tower to get it started again. Feels like a ground issue, but I could be wrong. I keep reading about a transmission-to-frame ground strap, but for the life of me I cant find it. Does this actually exist on a 2012 ? I haven't been able to find pictures of it that i think are actually from a n18 engine.

For reference , the car only has 60k on it.

Appreciate any advice

 

Any fault codes?

Does sound like an engine ground issue. Does this^ always work to restore engine cranking and, when it does, is the cranking strong or weak?

Post a picture of the ground strap you replaced.

What voltage do you read across the battery posts when you try to crank the engine? What voltage do you read at the disconnected starter solenoid connector when you try to crank the engine?

 

It doesn't always work on the first try, but usually it does and I can always get the car started when i do it, although sometime it takes holding the button longer. When it does turn over, its like a normal start strenght.
Battery reads 10.7 at the lowest while cranking.

This is the replaced cable





Upclose of some fraying.

overall , the cable seemed firm and not frail. I replaced it becasue every time I would fiddle with it, the start sequence seemed to get better or worse.


so is there no ground strap on the transmission housing? would explain why I cant find it

 

I forgot to mention, I cant easily get under the car, is it possible to reach the starter from the top?

 

Yes
You’ll need to remove quite a few items. It’s a very doable but takes a bit of time. you can see the top of it in this shot. Access from top yes but you’re still going to heed to get under it if you’re going to remove it. Two of the three bolts are easier to access from underneath.

Do yourself a huge favour and get a Bentley manual from ECS tuning
If it’s your first purchase from them you can usually save a few $$$
it’s worth every penny.


If you don’t have jack stands, don’t get under the car while supported with floor jack only.

 

Do you have a scan tool that reads live data? If so, use it to graph or monitor CAS module terminal 50L and 50E voltage and amperage before and during attempts to crank the engine. Terminal 50L is the 12V sent by the CAS module to the starter solenoid.

Any fault codes?

 

I don't have the ability to read live. I can pull codes via odbc. I did get codes for cas and dcs and a few others , but when cleared , they only would show back up when the car didnt start, so I assumed they were from the low voltage . if the car started for a week straight, I didnt get codes ( i checked every time ) . As soon as the car failed to start, one of more of the codes would return and the traction control ight would stay on until i restarted the car normally
a0b4 Fault Enginestart starter ( not present)
a8ac Corner light left defective ( my fog light is actually out )
3735 CAN message Rain Sensor - Wiper Speed (Pressent)
a12d Hardware error light sensor (present)
a128 Hardware error rain sensor (present )
d375 CAN message f can acln ln 1 id:0x0e3 (not present)
5e38 yew rate error step ( present)
5e46 logitudinal accel sensor error steo (present)
CAN Message f can acln acro 1 id:0x0d8 (Not present)
d373 CAN Message f can ywrt 1 ID:0x0d8
.

what is the recommended tool for pulling live data?
I'm planning on keeping the car so if its not crazy expensive I could grab one. And the Bentley manual

as far as getting under the car, I have jacks and stands, but what i don't have at the moment is flat ground to work on.

 

CAN Message f can acln acro 1 id:0x0d8
What code is linked to this^ description?

I have this scan tool: Launch X431 pro elite v2.0 for BMW
But many Mini owners opt for this Foxwell scan tool:

 

Quick voltage drop test to check your engine ground:

Set multimeter to read DC Volts. Place one probe on the negative battery post (not the connector) and the other probe on the engine block.

Have someone try to crank the engine for you.

You should read ~zero volts. If the meter jumps to 0.5V or higher, your ground is failing under load.

 

oops.. missed the code on that one. it was d374.
tested the multimeter on negative terminal and block. car started 4 out of 5 times.
once strong, 0.00 on the MM
the other 3 times 0.16, 0.16 and 0.25.
the time it didnt start was 0.19.

 

Did you do the voltage drop test with probe on (-) battery connector or post?

With that said, your results say that the engine ground path is fine.

Next voltage drop test (when you can raise the car on jack stands):

1. Connect red meter probe to positive (+) battery post.
2. Connect black meter probe to large starter nut where the thick red cable from the battery attaches.
3. Have somebody crank the engine for you.
4. If you measure more than a 0.5V drop, there is excess resistance in the red cable or in the battery cable.
5. If you measure less than a 0.5V drop, the starter may be bad.

 

I tested it on the top of the battery post itself, not the connector.
I'll try to get under there and poke around when i can get her on flat ground or i'll just get a new starter and pop it in if that's the likely culprit.

so just to double check ...there is no ground strap from the transmission housing to the frame? that's made up AI hallucinated nonsense, correct?

 

CORRECT!
I believe the Mini R53 may have had a transmission ground. The engine cable you replaced and that tested good is the only ground wire you needed to be concerned about with respect to the R56 starter. Focus now on the power path for the starter issue. If that's fine, then replace the starter.

 

Thank you. Ill focus on getting her up on flat ground and checking the starter and its connections next. Really appreciate the help. Will be a few days , but ill report back.

 

Thank you to everyone that chimed in, especially @Maybe, maybe not. It was the starter.

Side note, I've probably changed 20 starters on various cars since the 80s and this has got to be the most difficult one to do, even with reading the forum for the tricks. If it helps anyone, there was no way I was getting mine out the bottom as my exhaust just wouldn't move enough to get it by.
I went out the top and had to thread it under the heater hoses and over the shift linkage after detaching the bracket, then spin it just right to get it out. I also did not remove the intake and doing so probably would have made it easier.

 

Great work doing a difficult job!