P38 4.0 Gems not charging

Hi, I have a 1998 P38 and the battery light is not coming on with the ignition, the alternator is not showing any charge, I’ve changed alternators for a good second hand one and still no joy, I’ve earthed the brown and yellow body to the chassis and battery light then comes on ( engine not running)
Any more suggestions , could this be a BECM fault and if so are they interchangeable or do they need recoding? I don’t have diagnostics .
Cheers
Rob

if the dash light doesnt come on with the ignition then the bulb could be blown
have you checked the alternator is getting a signal on the small wire?

kermit_rr said:

if the dash light doesnt come on with the ignition then the bulb could be blown
have you checked the alternator is getting a signal on the small wire?

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Dash light works if I earth the small brown and yellow wire.