Sorry I don't know the code but presumably it’s referring to the inhibitor switch which is mounted on the end of the transmission’s selector shaft on the right-hand side of the transmission (beneath a tin cover which protects it). The ECU interprets the continuity between the different wires to determine which gear is selected at the transmission. For example, it uses this signal to ensure that it only allows the starter to operate in P & N.












The switch in the photos above is actually on a Ranger Rover 5HP24 but the E53 is identical except for the length of the wires (it therefore has a different part number). The wires are longer on the Range Rover as the connector is mounted up above the transmission bellhousing - rather than below it on the X5 - presumably for ‘off-road’/wading reasons.

If you want to test the function of the switch just unplug the connector underneath the vehicle and use a multimeter to check that the continuity between the wires is as shown in the table.

Incidentally, on the GM 5L40-E transmission used in the 3.0 litre models the switch is mounted inside the casing so the sump has to be dropped to access it.



Phil