Blower fans

Jazydave said:

Evening folks, could someone who's good with p38 electrical, point me in the right direction please?
Both blower fans have stopped working.
The fuses are good and have power, no power to fans on fan plugs. Relay 6&7(in underbonnet fuse box) not operating. They have power but they are not getting an earth to allow them to operate from what I can see.

Fusebox seems clean as a whistle, no heating /burning

My question is where should that earth come from?
I take it it's a switched earth. Does it come from becm? If so which wire/pin?

Thanks for your thoughts in advance
Dave

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Jazydave said:

Hi yeah, thanks for reply.
it's the heater fans, I thought they were fed from relay 6&7 in underbonnet fuse box?

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Datatek said:

No, they are controlled from the HEVAC. Relay 6 & 7 provide the permanent 12 volt feed to the motors. Relay 6 & 7 are energised by the ignition switch via the BECM. If those relays do not energise, suspect the ignition switch or connectors to the BECM.
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Jazydave said:

Yes that's it, they're not energised.
From your cct diagram, I'm thinking connector C1288 at becm not providing an earth path for relay coils?
Does that sound plausible to you

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Datatek said:

C1288, C1280, C0028/3, C0028/4, ignition switch contacts or the ground connection, depends if anything else is not working from the ignition switch. Does the HEVAC display illuminate with the ignition in position #2?

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Datatek said:

C1288, C1280, C0028/3, C0028/4, ignition switch contacts or the ground connection, depends if anything else is not working from the ignition switch. Does the HEVAC display illuminate with the ignition in position #2?

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pwood999 said:

@Jazydave what year is your P38 ? Although the diagrams & wire colours are the same for all versions, the connector numbers are different between 1994-1998 nad the 1999 onwards cars. There could be other subtle differences, but definitely check the relay, BECM & Ingition connections..

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Datatek said:

C1288, C1280, C0028/3, C0028/4, ignition switch contacts or the ground connection, depends if anything else is not working from the ignition switch. Does the HEVAC display illuminate with the ignition in position #2?

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Jazydave said:

Hi Datatec, thanks so much for cct diagram and explanation.
Proper good help

I think I've solved problem.
There was no earth from becm to relay 6&7.
I cut wire between ignition to becm, every time I touched it together again, I could hear a relay operate in becm.
After 10 or more times, fans came on intermittently. Then as I done it more, they came on every time!
I'm thinking dirty contacts on relay in becm, possibly self cleaning with increased operation?
Do you think that happens?

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Datatek said:

Relay contacts do self clean to some extent, not so much on modern stuff. If you are unlucky, the fix may not last long. You may end up having to open up the BECM and clean the contacts.

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Jazydave said:

Hope not. If I do, what's the best way to clean them?
When I was an apprentice they used to have us cleaning them with burnising tools in telephone exchange, but I imagine that's a bit rough for modern equipment.
Thanks again

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