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Thread: More Battery Problems

  1. #61
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    Much of the car is live (12V) and then switched on by being grounded.

    The pumps are driven PWM as I recall. (Think switched on & off rapidly, with the average ON time being what gets the desired pressure.)

  2. #62
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    Went straight to the pumps and still had 12 volts at both Left hand and right hand!
    Took out the relay - still had 12 volts at the pumps and senders. Took out the diode - no difference. Checked the relays for heat - only one warm, probably operating the boot/cabin lights?

    I thought that the fuel relay was the 'switch' for the current to the pumps? If that is so, I should not have current running to them when ignition is off or when everything is shut down or when the relay isn't there.
    Thats correct

    Looked at the wiring diagram and it seems that the supply to the pumps from the rear box is a lone harness coming off the main one where it passes through the metal bulkhead at the base of the seat-back. Maybe you have a short there as something supplies the 12v to the pumps and senders.

    The fuel pump relays have 2 12v feeds. 1 is a switched 12v feed coming from the ignition switch true fuse 4. its a 5 amp fuse (primary fuse box).

    1 12v feed coming from fuse 19. its a 15 amp fuse (rear distribution/fuse box). Going true the relay number 7 (fuel pump relay. It's a smal relay underneath the fuse cartridges at the right of the diode) to the RECM connecter CA101-01.

    Connector CA101-11 and 12 go to the fuel pump. Its the RECM that controls the pumps but the only task of the fuel pump relay is to provide the 12v.

    So with the fuel pump relay or fuse 19 removed or the ignition switched off there should not be any 12v at the pump(s).

    Connector CA101-15 and 16 are for the return signal of the fuel senders and CA103-23 is the feed coming from the RECM for the fuel senders. The RECM gets its feeds from fuse 4. its a 5 amp fuse (primary fuse box) to connector CA100-8 and fuse 20. 10 amp at connector CA101-3.

    Disconnect CA101 (20way black connector) from the RECM. Do you stil have 12v at the pumps? If that still the case you have a short in the wiring going from connector CA101 to the loom of the pumps/fuel senders.

    The trunk lights are connected at CA100-11 and get there feeds from fuse 4 of the rear fuse box. The trunk switch is connect at CA102-14 and switches to earth. These don't use a relay but uses the RECM to do the switching off and on.
    '71 Ford Capri 7.0l V8 Dart block with EFI and a modified Dodge Viper 6 speed.
    '69 Ford P7 20M Hardtop coupe with the running gear and with all electronics and aircon/heater of a '01 3.0 v6 Jaguar S type.
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  3. #63
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    Thanks chaps, I'll get on to it tomorrow and see if I can now resolve this. Its good to get a response that agrees with my own investigations, just a bit more technical to help me on my way. I'll see if I can find this short first, but the way the wires disappear under the back seat panel doesn't fill me with confidence and I don't relish opening up the looms. Hopefully it will be more obvious.
    Current Vehicles: 2001 Jaguar S-type 4.0 V8 Pacific Blue, Ivory leather, Dynamic wheels
    1999 Jaguar XJ8 4.0 V8 Madeira pearl metallic, Oatmeal leather, Nice jag wheels
    2012 Jeep Compass Limited 2.4 Auto, Gunmetal, black leather, big 18" alloys
    1956 Fordson major diesel, Sky Blue, perf. metal seat, orange 36" wheels

  4. #64
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    So, this morning I went straight to the relay and checked it out, all ok, then went to the fuel pumps/senders and decided to clean up the terminals and re-test for voltage. Then checked wiring from recm and loom to pumps where I could. I must have done something a bit good, because on re-testing the results were as follows:

    1. Car fully shut down, no ignition/no relays on/nothing: RHS pin 1 - fuel level sensor signal supply (white/red) live 12v. Nothing else. LHS Pin 1 Fuel level sensor voltage supply (brown/blue) live 12v.

    2. Ignition on, Same as above, but in addition RHS pin 2 - Fuel Pump voltage supply (Green/Orange) live 12 v.

    Thanks for your detailed response capriV8driver. I now know that the relay is ok, the pumps only get called up when ignition is on, which seems ok to me, but if I take out the relay I still have power to the pump when the ignition is on not when it is off!! So there is still a short to find somewhere. But what about the senders? Should they be still live on shutdown?, or as O4str says, these may be part of the circuits that remain live on the vehicle but inoperative until grounded by 'switch on'? If this is the case, then the short might be between the sender voltage supply and the pump voltage supply, as the supply to the pump remains on after switch on with the relay removed. Get my drift? This could be a duff connector plug rather than a short couldn't it?
    Thoughts please on where to go next!
    Current Vehicles: 2001 Jaguar S-type 4.0 V8 Pacific Blue, Ivory leather, Dynamic wheels
    1999 Jaguar XJ8 4.0 V8 Madeira pearl metallic, Oatmeal leather, Nice jag wheels
    2012 Jeep Compass Limited 2.4 Auto, Gunmetal, black leather, big 18" alloys
    1956 Fordson major diesel, Sky Blue, perf. metal seat, orange 36" wheels

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