Rover Mini electrical problem

[ULTIMA69]

Hi My Mini stopped today for the second time symptoms - blows a fuse not sure what fuse feeds, engine stops and starter fails to turn over. Replace fuse, fuse does not blow imediately car sometimes will start and sometimes wont. When it won't start its like the immobiliser is not switching off with fob but you can hear a few clicks under bonnet when fob is pressed any ideas?
Has anyone got a fuse number list so I can find out what the fuse is for. Thanks Dave

[intrepid]

Not sure if this helps but I had a similar problem with the 30amp fuse that protects the lighting circuit.

The cause was the radio had worn through the cables behind the dash - the radio sits over them and with constant bone-shaking (quiet hard suspension on our Mini) it caused them to short circuit and blow the fuse.

Maybe the same problem with yours but the ignition circuit?

I have re-insulated mine and placed a protective layer over the wire so it does not happen again - no fun when your lights go out late at night!!!

[Camel]

Not sure what it could be, you will probably have to work around each circuit from the offending fuse and look for an intermittent short?

Here are the fuses anyway, engine compartment left to right:

1 30 amp N Passenger compartment fuse box - fuses A9, B1, B6, B9 & C4
2 30 amp N Ignition switch, auxiliary relay
3 30 amp N Lighting switch
4 30 amp N MEMS relay module / manifold heater relay (Japan)


and passenger compartment C, B, A left to right across the top and 1 to 9 down the side:

A1 10 amp UW RH headlamp main beam, driving lamp relay
A2 10 amp UR RH headlamp dipped beam
A3 10 amp RW RH side and tail lamps
A4 10 amp W Alarm ECU, instrument pack, voltage gauge, oil temperature gauge
A5 - - Not used
A6 10 amp G A/C relay, switch pack, thermostat, seat belt warning lamp, catalyst overheat ECU (Japan only)
A7 15 amp LGW A/C blower motor (Japan only)
A8 15 amp LGO Blower motor
A9 20 amp U A/C relay (Japan only)
B1 15 amp P Driving lamp relay
B2 10 amp UO Rear fog guard
B3 10 amp R Headlamp levelling
B4 10 amp LGW Radio cassette, cooling fan relay (Japan), automatic gearbox selector indicator lamp
B5 10 amp G Airbag control unit
B6 20 amp P Alarm system and horn
B7 15 amp R Sunroof
B8 15 amp LGO Wipers and washer
B9 15 amp P Cooling fan
C1 10 amp UW LH headlamp main beam
C2 10 amp UR LH headlamp dipped beam
C3 10 amp RB LH side and tail lamps
C4 10 amp PO Radio cassette, clock, brake system warning light, direction indicator /
hazard warning light, anti theft alarm indicator light, interior lamp unit
C5 - - Not used
C6 15 amp G Direction indicator relay, brake and reversing lamps
C7 10 amp NS Inertia fuel shutoff switch
C8 10 amp WR-WK MEMS relay module (starter switch)
C9 15 amp G Heated rear window


Hope it helps

[ULTIMA69]

Hi Thanks for the info I will have a go on the car tomorrow. Let u know what it was when I find out. Dave

[ULTIMA69]

Hi again the blowing fuse is the fuel pump fuse, however this doesn't explain why it won't actually turn over sometimes or un-immobilise itself. I suspect the relay module a trw unit 4 relay unit as this has the fuel pump relay as well as the starter relay, any one had problems with these?

[Camel]

The section on the fuel pump in the manual indicates that it is linked to the inertia fuel shut off switch. I wonder if a short or something is causing that to switch off and thus preventing the engine from starting??

DESCRIPTION AND OPERATION
4.14 MINI
FUEL PUMP
OPERATION
General
One side of the fuel pump relay coil receives battery voltage from fuse A4 in the passenger
compartment fuse box on a W wire provided the starter switch is in position II. The other side
of the relay coil receives an earth on a BP wire from the MEMS control unit provided the
correct operating conditions exist, (see Engine Management System) causing the relay to
energise.
The energised relay switches battery voltage from link 4 in the engine compartment fuse box
on an N wire, via fuse C7 in the passenger compartment fuse box to the inertia fuel shutoff
switch on an NS wire. Provided the inertia fuel shutoff switch remains closed, battery voltage
is fed on a WP wire to the fuel pump. Since the pump has a permanent earth on a B wire it
will commence operation.

[ULTIMA69]

Hi I took inertia relay off and shorted the two wires to bypass this. However I still have the same problem. I am being lent a YBW10022 relay block - engine management relays and I will see if this does anything. Also what does the immobiliser key fob trigger has it got a receiver in the ECU? As I wondered if this has an intermitent fault (I have put a new battery in fob). Dave

[ULTIMA69]

Hi Relay block made no difference. Any ideas?

[Camel]

There is an alarm ECU, it's behind the centre of the dash near the ashtray, but I'm afraid ECUs are way beyond the limits of my electrical knowledge

[ULTIMA69]

Hi Checked this it appears that I have an intermitant connection/wire brake fault from the alarm ecu to the engine ecu. As when I move the alarm ecu around I can cause or remove the fault, just need to find which wire or connection is faulty, homing in on the fault though. Cheers Dave