Gear box m & s light isues
 

Firstly hello to you all as this is my first post on this site.

I am having issues with my gear box. I have a 2001 disco 2 and recently the gear box m & s light keep coming on and the box goes into limp mode.

So far I have changed to atf oil twice.
Changed the gear box filter and seals
Replaced the battery with a new red top optima
Changed the XYZ switch
Had the XYZ switch adjusted and checked on a diagnostic machine

Nothing has made any difference

However the gear box still keeps playing up. It only ever causes trouble when it's cold / first started and put into reverse; then it goes straight into limp mode.
The other issues and the most annoying one is some times it will not start due to the inhibitor switch I assume. Eventually if I keep trying it will start but then I will not be able to put it in revers until warm.

Any ideas to solve this would be great fully received. It has been surgested that I need to change the box wiring loom. However I wonder if it could be a voltage issues. If so any why I can check for sure before looking at changing the loom.

Many many thanks in advance.

Form personal experience I suggest you first swap your battery with a known good one from another vehicle. See if it does the same thing at startup. I know you have a new battery but I'm not clear whether the problem went away when you put it in, or if it did okay for a time, or if it made no difference. If it didn't make any difference, disregard swapping the battery. I had similar trouble and it was a bad battery, but you might have a different situation.

And when you say it won't start are you referring to the engine or motion of the truck?

Changing the battery made no difference. So far nothing has.

And by not starting I mean the engine, it just clicks as the inhibitor won't let it start. I have had it checked after and it shows a mis read on the xyz switch. But the switch is new and properly calibrated. It read correct in all gears even if wiggled in gear.

Double check the wiring diagram in Rave, but I'm pretty sure the transmission is wired to both the ECU and the BCU. Even with a new XYZ switch, if the connections at ECU are corroded, it will get bad data.
Before my scangauge quit talking to the ECU altogether, it would only work after I got the passenger footwell (location of ECU) warmed up.

What is your voltage at idle?

I Will check idle voltage tomorrow.

Does the gear box talk to the slabs and the under bonnet ecu then?

It's true that low voltage can trigger the flashing M&S lights but there are over a dozen transmission faults that can also cause the M&S lights to flash. I suggest that you get the transmission codes read so that you can accurately diagnose the problem.

Ive had the codes read 3 times now. It only ever show gear box switch miss read

You might want to read my thread about scangauge not communicating with the ECU. I cleaned all my ECU connections with plastic-safe CRC contact cleaner (a whole can) and a nylon parts cleaning brush.

This shows the wiring layout.