[willisodhiambo]

Someone was checking fuses in this car then suddenly it fails to start. Cluster comes on but turning key to start position does nothing. Cluster goes off in the start position. Tried jumping starter, starter seems to work.


I got Chinese op-com and managed to connect to the car. Ecus with communication are Radio, cluster, airbag, headlamp, AC, seat module and parking assist.

These can't communicate, fuel pump, BCM, EPS, engine and transmission.

Checked engine bay fuses and they look good. If I had wiring schematics I might have a chance at trying to fix this.

Any ideas where I can start? I have a feeling the BCM might be the cause, power supply issue. I have BMW knowledge so with a little guidance I might be able to trace the fault.

[budzasto]

Check CAN communication wire (wire's). They are likely to be interrupted or short-circuited

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you have to disassemble the fuse box, you have 3 groups of wire leads

[willisodhiambo]

Check CAN communication wire (wire's). They are likely to be interrupted or short-circuited

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you have to disassemble the fuse box, you have 3 groups of wire leads

Thanks, ill see what can be done. First will try find the can wire diagram then I can try trace

[hahn181]

What insignia`? Year? Engine-Code?

If you can tell me these details, I can give you any schematic you want.

VIN would be the best to find everything related to your specific car

[willisodhiambo]

What insignia`? Year? Engine-Code?

If you can tell me these details, I can give you any schematic you want.

VIN would be the best to find everything related to your specific car

W0LGT6EMXD1129771. 

I did get a schematic and began checking fuses. I do notice one major give away. The gear position is not showing on the lever!!! So i think car has no idea which gear it is in and thus not allowing crank. All fuses are good but could not see any voltage on fuse 01 engine bay which I think is the transmission supply. BDC is online but cant scan engine ECU and Transmission CU. 

Will continue probing.

[hahn181]

Hi,

ok I looked for your vin and found a ton of information.

I quickly collected to most usefull (in my opinion) and uploaded it as an attachment.

You should take a look at instrument_fuses_en Fuse 24 it is controlling the following items:

E2RF marker light - front right side, E4LF indicator light - front left, 

E4N parking/indicator light - left (TT4), E4P parking/indicator light - right (TT4), 
E4Y side indicator light - left, E5AL tail light - right outer, E5H tail light - right inside, 
E8S comfort light in trunk, K9 body control unit, K33 heating/ventilation/air conditioning control unit, 
KR70 accessories power supply relay, M93, P2 display for position of gearshift lever (MDK or MH7), 
S2 switch for manual transmission (MDK or MH7), S30 switch for headlights, 
S48C Multi-function switch 1 - instrument panel, S48D Multi-function switch 2 - instrument panel,
S70L Steering wheel controls switch - left, S70R Steering wheel controls switch - right,
S91 Parking brake control switch, S107 Park pilot on/off switch (UD7), 
X81 Accessory socket - 110V AC (KI6) ,X420 (early production RUE)

anyway... Look at the files I uploaded. If you see an direction, just tell me whats your system or ecu of interest and I can provide you the whole Factory Diagnostic Troubleshooting manuals and schematics etc.

hope it helps

[willisodhiambo]

Thanks. Let me take a look. I need information on fuse 01 engine bay. It is my first suspect, Opening the fuse box to see if there is any explanation for missing voltage. Will also trace powerline to TCU to confirm it comes from fuse one. Thank you very much for your help. Even with my BMW knowledge, working on tis model seems like rocket science

[JV22]

Hi see if the fuses are in place

[hahn181]

The Fuse F1UA (as you said the F1 enginebay) has B+ on one side and goes directly to the gearbox ecu "Connector X1 pin1" (which is mounted on top of the gearbox)

So if you pull the fuse and you have 0 Voltage on both Fuse-Pins, it would mean that there is B+ missing.

Have you checked the BIG Fuses mounted on the battery?

And just to be sure... is the Battery charged enough? Because the Technical Information says, that the BCM in this car has an undervolt check and will refuse zu turn on the bcm module etc. If it has more than about 11,6 V it should not matter.

[willisodhiambo]

This is lots of information!! I have a feeling with your help I will nail this.

Removed the fuse box and tested it again. Fuse 01 is OK and is getting voltage. Will install back in the car and follow this diagnosis plan. If i recall well I did not see these errors in the BCM. Will scan again and see what DTCs are stores relating to ignition circuit