"M" and "S" lights illuminated on dash when started engine

Bruxey · May 12, 2012

Hello, I have a 2003 Disco 2 xs auto

Last week I'd been driving for a bit and then parked up, to get a quote on some rust repair funnily enough (damn window struts!). When I came back to the car and started the engine, the green "M" and "S" lights stayed on and the digital gear indicator was flashing. Thinking "oh bloody hell what's this now?", I turned it all off; left it a moment and then started it again. It seemed to be ok and I made it home. On consulting the manual, it says if the manual shift light and the sport light stay on together and they don't extinguish after pulling to a halt and turning off the engine, then there is a serious electrical fault with the gearbox.

I know in this instance they did go out after I turned it off and it has never happened again since or before that occasion but I'm just a bit concerned that it's a sign of the start of a problem.

What could have caused this, did it just have a bit of a brain fart or is it likely there's an issue here, rearing it's ugly head??

Thanks in advance for any input.

iansoady · May 12, 2012

Most often it happens because the battery voltage is a bit low on startup and the control unit sees this as a fault. It started to happen to mine and a new battery cured it.

The other common(ish) problem is water getting into the XYZ switch which controls the shift position. If you have aircon the drain drops water straight onto this switch (on the LHS of the gearbox). The harness to the switch sometimes gets frayed as well.

thebiglad · May 12, 2012

Bruxey said:
Hello, I have a 2003 Disco 2 xs auto

Last week I'd been driving for a bit and then parked up, to get a quote on some rust repair funnily enough (damn window struts!). When I came back to the car and started the engine, the green "M" and "S" lights stayed on and the digital gear indicator was flashing. Thinking "oh bloody hell what's this now?", I turned it all off; left it a moment and then started it again. It seemed to be ok and I made it home. On consulting the manual, it says if the manual shift light and the sport light stay on together and they don't extinguish after pulling to a halt and turning off the engine, then there is a serious electrical fault with the gearbox.

I know in this instance they did go out after I turned it off and it has never happened again since or before that occasion but I'm just a bit concerned that it's a sign of the start of a problem.

What could have caused this, did it just have a bit of a brain fart or is it likely there's an issue here, rearing it's ugly head??

Thanks in advance for any input.

It's almost certainly a weak battery, put it on charge overnight and monitor the situation.

There may be enough juice to start the engine, the problem is that the ECU's need a good supply of volts and if the battery is weak, the starter motor sucks the battery dry for a couple of seconds, so the autobox ECU gets no volts !

gazjacko · May 12, 2012

Mine does this every now and then, I changed the XYZ switch and it still occurs every so often, sometimes for a day or so on 'limp home' mode. I'm convinced it's the wiring somewhere but currently it's OK so I can't get anyone to check for a problem that's not there at the moment.

Bruxey · May 15, 2012

Had it hooked up to a hawkeye yesterday when I was getting my A bar fitted, seems to be clear of faults now. Mechanic put it down to moisture shorting the circuit (had just waded through some fairly flooded roads). Unfortunately On the way to work after picking it up, the TC, ABS and Hill decent lights came on for the first time! Turned it all off and they went out. Happened again today so took it back to my garage and they hooked it up again. There was a historical fault on the shuttle valve which he cleared, hasn't come on since, fingers crossed it was a glitch!

thebiglad · May 16, 2012

Bruxey said:
Had it hooked up to a hawkeye yesterday when I was getting my A bar fitted, seems to be clear of faults now. Mechanic put it down to moisture shorting the circuit (had just waded through some fairly flooded roads). Unfortunately On the way to work after picking it up, the TC, ABS and Hill decent lights came on for the first time! Turned it all off and they went out. Happened again today so took it back to my garage and they hooked it up again. There was a historical fault on the shuttle valve which he cleared, hasn't come on since, fingers crossed it was a glitch!

I'm not sure what you mean by "A bar" but if the mechanic went anywhere near any of the wheels he may have accidentally knocked a piece of wiring that leads to a wheel sensor.

"M" and "S" lights illuminated on dash when started engine

Bruxey

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iansoady

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thebiglad

Well-Known Member

gazjacko

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Bruxey

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thebiglad

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