Fan wiring - help please!

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KevR
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Fan wiring - help please!

Post by KevR » Mon Sep 14, 2015 3:54 pm

Right then. I suspect the fans on the Grey One have never worked. I've certainly never noticed them cutting in, and in the Alps recently the yellow light came on briefly so definitely too hot for comfort. I tried shorting the switch connector but got nothing, so I wired one fan (the other was seized) straight to the battery and all was well.

Now I want to make it work properly. Have replaced the seized fan and remade the connections. Shorting the connector still doesn't work. Traced the blue wires from the switch connector - one (left upright of the U formed by the three connectors as you look at it) to the fans , one (bottom of the U) all the way back to a connector block on the main fuse board. I'm assuming this should be live at battery voltage - is that correct? If so, it's not. So next step, check fuses again, and double check all relays on main fuse board and the ones by the washer bottle (I've got plenty of spares so have substituted them). Still nothing. Presumably something within the fuse board has failed, meaning no supply to this wire?

As an experiment, connected a live feed directly to the relevant terminal on the switch connector (the bottom of the 'U'). Bingo - both fans run slow when bridging the left of the U, and both run fast when bridging the right of the U. All as it should be.

Naturally, though, they don't stop when you turn the ignition off...

It seems to me easy enough to provide a live feed to the bottom of the U using a relay triggered by a switched live, and everything will work. I'd also like to add dash switches to the other two connections so I can ovverride the thermo switch, if only to test the fans actually still work every now and then. Again, easy enough

The question is, though, have I missed something. The wiring diagram in the only Haynes manual I have is worse than useless so for all I know there might be another component somewhere which could have failed or have a poor connection.

So, before I launch into rewiring it, anyone got any clever ideas as to what I might have missed....?
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

Kaapelimies
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Re: Fan wiring - help please!

Post by Kaapelimies » Mon Sep 14, 2015 4:58 pm

TD or something else with aircon?
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

KevR
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Re: Fan wiring - help please!

Post by KevR » Mon Sep 14, 2015 5:44 pm

Sorry, yes - TZD. No aircon.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: Fan wiring - help please!

Post by Kaapelimies » Mon Sep 14, 2015 9:49 pm

There might be several options on the wiring, but my TD had a straight wire to the thermoswitch from the splitter in the battery cable, no fuses.. Colored light blue. If the connector has come loose it may disconnect itself.
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

Tinkley
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Re: Fan wiring - help please!

Post by Tinkley » Tue Sep 15, 2015 6:57 am

Might be worth checking the brown multi connectors especially the one near the battery, I know one of the wires on my Athena is broken just on the edge of the connector. Also the state of the wires.brass connectors inside? In my case I think it is the oil level start up indicator as I know the sensor works on this engine. Easy enough to check now and again manually though so I haven't bothered to fix it... :wink:

However I need to check my fan operation too so will be joining you in the great exploration of Citroen wiring :lol:

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Re: Fan wiring - help please!

Post by KevR » Tue Sep 15, 2015 8:17 am

Thanks for the suggestions. I'm sure there are different fan wiring setups depending on model, number of fans (Mine has two) and whether it's got aircon or not. I think a second fan was also available as an accessory for towing on some single fan models, and came with an extra add-on wiring harness, to further complicate things...
On mine The blue wire from the bottom of the sensor plug definitely goes to (or rather comes from) the main fuse box. The blue wire from the main battery splitter goes to one of the relays by the rear washer bottle. Neither of them goes via a connector. It's possible that the green wire from the sensor goes via a connector but I don't think so. I'll check. About time I checked the brown conectors again anyway....
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: Fan wiring - help please!

Post by themildbunch » Tue Sep 15, 2015 2:43 pm

Yours sounds like mine - a 2 fan TD.. You should have a 3 wire connector on the rad switch...

I'd think it's likely to be a wiring fault, the relay or the fan resistor (a silver can clipped near the fans) ---

This is useful from the BX DIY site:
16 and 19 engines: The fan control switch is screwed into the right bottom of the radiator. It is a double temperature switch with three blue wires: the ground has a brown sleeve, the low speed contact has a yellow one and the high speed contact has no sleeve. Jumper the brown to the yellow and the fan should rotate in low speed. Jumper the brown to the sleeveless and the fan should rotate in high speed. If it does not work in either speed, check its ground: touch the wires mentioned above to some exposed metal part instead of the brown sleeve wire. If only the low speed fails, the low speed resistor (an aluminum cylinder with a 3-pin white connector at one end) located right behind the left headlamp is suspect.
1988 BX 19 Gti 16v
1991 BX 17 TZD Estate
1991 BX 17 TZD Estate

KevR
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Re: Fan wiring - help please!

Post by KevR » Tue Sep 15, 2015 5:59 pm

Yes, it's a three wire switch - but two are thick blue wires, one is thin and green.
I thought the silver can (with a brown connector on mine) between right headlight and fans was the dim/dip relay...?

If the resistor wasn't working, then surely the high/low fan wouldn't work when I feed 12V to the bottom switch terminal?
More or less 100% sure it's not relays - have swapped them out and still nothing. Will double check though.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!