Jazydave · 2024-11-25T21:28:09+0000

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

Datatek · 2024-11-26T08:01:11+0000

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

Are you talking about the heater fans? If so they are variable speed and controlled from the HEVAC not the BECM no relays involved. The radiator electric fans are controlled by relays and only operate for the aircon with an earth via the tri state switch. If there is not enough gas in the system, they will not operate. I need to look at RAVE for more details.

Jazydave · 2024-11-26T09:18:33+0000

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

Datatek · 2024-11-26T10:25:24+0000

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?

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.

Jazydave · 2024-11-26T11:47:31+0000

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.
View attachment 330743
View attachment 330744
View attachment 330745

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

Datatek · 2024-11-26T16:13:01+0000

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

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?

pwood999 · 2024-11-26T17:40:25+0000

@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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