Discovery 2 TD5 M+S Lights Flash Black XYZ / Inhibitor Switch Removal, Refurb and Replacement how to

I went to start the truck and had the dreaded green M+S lights flashing on the dashboard (and limp mode previously too) and it wouldn't start, so checked the battery voltage/terminals that was all good, so tested the gears and it wouldn't show some of them which lead to us a faulty XYZ / Inhibitor switch other issues can cause this though. Currently these switches are £700+ in the UK to buy so that wasn't going to happen, and £50 to be refurbished Nov 2022. Previously I had noticed that sometimes the truck wouldn't start by key after using it, then would be fine until the switch stopped working.

Make sure the exhaust is cold or remove it first. The switch is located on the side of the gear box, has two 10mm bolts and the gear level cable attached via a link. It's difficult to get to and you can remove the exhaust downpipe but we chose not to, the switch has metal aluminium and black plastic parts which are riveted together, you can drill those out with a 4mm metal drill bit. As it's a rotary switch there's a part that moved with the gear box shaft and below that there's several metal tracks that the switch contacts with at different positions to tell the computer what gear you're in. When we removed the part that turns, it has four copper fingers with others with little metal pads and one of the pads had electrical arcing so was lightly sanded along with some gentle brass wire brushing in other places to clean it up. After that we used plenty of electrical contact cleaner and wiped it all out, and applied a little dielectric grease to the plastic parts which move which previously had some then resembled the switch with rivets, but you can use little bolts with nylock nuts. Just make sure everything is super clean, and if needed bend the copper fingers a little to ensure they have good contact otherwise the fault can happen again but be careful and don't damage anything.

When it comes to refitting the switch you need to follow a procedure, which is leave the gear lever in the P position in the car, then on the gear box shaft move it all the way clockwise to the engine then two detents (clicks) anti-clockwise to the boot/back of the car you will hear two clicks you can use the gear shifter cable arm to do this safely, some say use piliers but you risk damaging the shaft so not advised.

On the switch where the gearbox shaft connects it has a lots of little splines and a flat part which matched the metal shaft design, don't touch the spindle position just place the switch carefully over it (super clean and some grease/silicone can help), and make sure it sits all the way back then put the top and bottom 10mm bolts in, you can leave them a little loose for fine tuning but we didn't need to, but this handy if P is flashing on the dashboard then you can get somebody to tell you this and then turn the switch side to side until it's solid then tighten up. The gear level cable also needs to be reattached, if the gear e.g. P/N are solid and the M+S lights are flashing reset the ECU by disconnecting the battery for a few seconds, I cleared the fault codes on my OBD2 computer. There is a alignment tool, we didn't use it it but it's around £20-30 the instructions out there along with the haynes manual do say to use.

If you refit the switch and tighten the bolts it keeps flashing in P then it's not on the gearbox shaft properly, we had this issue so take it off and put it back on carefully just make sure it's clean and try again, remember the gear indicated on the dash and LED lights either side of the lever must be solid not flashing otherwise the switch isn't in the correct position.

We hope this video helps, and wish you luck if you have this issue yourself as we did struggle with access a little it's not easy. You will need a small 10mm ratchet, 13mm spanner, light source, dielectric grease, 4mm metal drill bit, rivets/bolts and electrical contact cleaner. Also consider using penetrating oil on the bolts and also a small wire brush to clean surfaces up as you don't want to slip or shear anything off as that would make this job even harder than it already is due to access.

If you have any questions please ask us, I will do my best we hope our experience and write-up above helps you out.

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