Becm fault on c258

P38crazy said:

Hi all
So I've finally found out why my Hevac and fans aren't working its a problem with the becm plug c258 not giving them power etc is there a way of DIY repairing this? I don't know if this is a common problem or not? Or is there a way of bypassing the becm so the Hevac an fans will work correctly
Thanks in advance for any information/help

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wammers said:

Have you checked fuse 8? If relay 7 is down your radio should also be off. Just try supplying a switched/fused (30amp) 12 volts to the White/Pink wire connected to C258.

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Thebest4x4byfar said:

Think I read you can swap the top board of becm over without any problems or diagnostics. A search on here may confirm

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P38crazy said:

Yeah I've checked all the fuses and relays I've also tried putting power to white/pink wire that turns the Hevac on but then the fans won't work
I do have another becm from a previous RR p38 I stripped and I have the key that goes with it but the fob is bust so when I connect that becm I can't start the car is there a way of deactivating the immobiliser/alarm or bypassing it?

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wammers said:

You can't have checked relay 7 it is inside the BECM.

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P38crazy said:

So I swapped the 2 power boards now everything is dare I say it working perfectly thanks everyone for your help you lot are a true god send

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P38crazy said:

So I swapped the 2 power boards now everything is dare I say it working perfectly thanks everyone for your help you lot are a true god send

Click to expand...

P38crazy said:

So I swapped the 2 power boards now everything is dare I say it working perfectly thanks everyone for your help you lot are a true god send

Click to expand...