Hi all. After several years of ownership my 2005 L322 petrol/gasoline v8 with the stock BMW M62 engine and a ZF 5HP-24 transmission at 139k miles I started seeing trans failsafe regularly after 10-15 miles of driving. The codes are typically correlated with a rough shift into 3rd or 4th and resulting limp home mode.

Wondering if any of you good folks have some guidance on where I should start to address this. Thanks in advance!

Fault codes are:

Shift Solenoid 2 fault (always)
Gear switch fault (infrequent)
Plausibility Fault - Transmission Range Sensor Circuit Malfunction (PRNDL input)

Additional info:

Bosch and Siemens units live data did not match with the (if I recall) the downstream Siemens transfer box module showing the shifter position as invalid when traveling in D after the trans fault. Can confirm.

It would make sense to eliminate the inhibitor (or gear position) switch from your enquiries before delving deeper into the transmission itself. Do you have the actual P codes for the faults, or are you using a generic (none Land Rover specific) diagnostic tool? The code that you’re looking for is P0705.

If the inhibitor switch is faulty, the controller doesn’t know what mode the driver wants the transmission to be in, so it defaults to failsafe i.e. locks the transmission in 4th gear. The switch is mounted outside of the transmission, so it’s possible to repair it without pulling the transmission apart.

Another sign that it is this switch at fault would be the selected gear position disappearing from the dashboard. Is ‘D’ definitely lit up when the transmission goes into failsafe?

Phil