Urgent !!! Flashing coil light

[Cobbvo]

Hi there my coil light has just started flashing whilst I'm away camping , my battery is dodgy so I'm running off the leisure battery , would a flat battery cause this fault ? I've swapped my healthy leisure battery with the knackered can battery but it's still on ??? Any help much appreciated as ive got a 2 hour drive home in the morning

[cmm303]

Flat batteries can cause flashing coil light on start up if the ECU detects it has lost backup. Usually resolved on a restart, assuming voltages are back up adequately.

Mine (1996 Diesel) will run happily with the LB disconnected - some things obviously don't work. So I wouldn't think running with a dodgy battery in the LB position will cause a flashing coil light to persist. Try disconnecting its earth and see if the fault clears, just in case the dodgy battery is dragging the voltage down.

The top left fuse (red 10A) by the drivers knee is usually moved over to run off the LB because it does the interior lights. It does however run a few other things. If this can easily be reverted (if you are lucky by replacing a spade terminal with the fuse for the LB circuit) to run off the normal SB feed then that should put all your ECU power feeds back on the single battery in the SB location. Its a long shot - I would not spend a lot of time or risk on this however, because AFIK its only the ECU backup which is powered from this circuit and I think the ECU is fine powered through its main feed which is always off the battery in the SB location.

Disconnect both battery earths before fiddling!

Apologies, not the straightest of answers. I don't know enough about flashing coil lights to get into the intricacies before you need to get going.

[mikeonb4c]

Hi there my coil light has just started flashing whilst I'm away camping , my battery is dodgy so I'm running off the leisure battery , would a flat battery cause this fault ? I've swapped my healthy leisure battery with the knackered can battery but it's still on ??? Any help much appreciated as ive got a 2 hour drive home in the morning

If you have/can get a multimeter you could check alternator charging output and battery resting voltage (though the latter may not give the full truth unless the battery is put under load)

[g8dhe]

The top left fuse supplies all the backup supplies, including that for the ECU if LB is flat then the ECU spots that it has reset and flags up a problem as it had no backup supply. Once you have run for a bit the LB should charge up, in until you next flatten it