The GM 5L40-E transmission has five solenoids : Pressure control solenoid TCC PWM solenoid 1-2 shift solenoid “A” 2-3 shift solenoid “B” 4-5 shift solenoid “C” so the difficulty is knowing which of these your generic code reader identifies as solenoid 1 My guess would be that it’s probably...

Sounds like the Direct Clutch is on its way out :( Phil

Just to mention that you should disconnect the battery before removing the 40-pin ECU connector for the continuity tests and, once the battery is disconnected, you may need to lift the latch gate manually to allow the shift lever to be moved through each gear position, for the checks. Phil

Your problem is either a selector cable adjustment issue or an inhibitor switch (xyz switch) issue. Clearly, it’s easiest to check the cable adjustment first. Underneath the vehicle, I would suggest that you slacken off the clamp bolt, slide out the cable, check that the clamp bolt is free to...

You have the ZF 5HP24 transmission and the New Venture Gear NV225 transfer box. The critical thing is whether or not ‘P’ is lit up on the dash when the starter fails to operate? Can you also just confirm that the message centre displays TRANS. FAILSAFE PROG rather than TRANSFER FAILSAFE? Phil

Failure to upshift beyond 3rd gear is a classic symptom of rear stator bush wear for the 6HP26. However, you would expect to get a failure code for the E clutch slipping, and it just seems too much of a coincidence that it started at exactly the same time as your tyre replacement. Phil

Re - 6. Transfer Box Module The ‘noise on actuator signal’ is a classic fault code caused by a dodgy shift motor potentiometer. On the other hand, low battery voltage (also identified) plays havoc with the ECUs Phil

Yes, if the four drive bolts had been removed this would explain your issue, but it would be a pretty weird thing for them to have done. This is what your Y85 converter looks like on the back – you can clearly see the 4 bolt positions. I did wonder if this hole in the engine casing, just above...

Okay, that sounds pretty serious, I’m afraid. My guess would be that the input/turbine shaft has snapped, or possibly an internal failure in the torque converter. Unfortunately, there’s a limit to what you can learn from diagnostics as nobody thought to allocate a DTC to a failed input shaft...

Do you mean that both wheels on one side of the vehicle are off the ground and, if you turn one wheel, then the other turns too? If so, that's just the centre differential doing its thing i.e. the front propshaft is connected to one side gear and the rear propshaft to the other so, even if the...

I’m not familiar with the 2.7 V6 engine, but usually there are rearward facing access plugs that you can remove on the engine or sometimes they use the starter motor hole for access (hence my suspicion). Clearly, this is a very long shot. I would strongly recommend that you get access to...

You have the ZF 6HP26X transmission and the Magna Steyr DD295 transfer box. The Fuse 37 thing only applies to L322 models with the earlier New Venture Gear NV225 transfer box used with the 5-speed transmissions (ZF 5HP24 & GM 5L40-E). It’s not relevant to the L320 as your vehicle can be towed on...

Does the park lock hold the vehicle stationary when the handbrake is off, or will it roll in Park? Phil

The torque converter is separate to the transmission i.e. you don’t need to open up the transmission to replace it, though you do need to drop the transmission out of the car to gain access to it. Any competent mechanic can replace a torque converter. There’s no specialist knowledge of automatic...

You have the ZF 6HP26X transmission. “...It's started to hang on to 4th gear up to about 3k revs before it can be forced to shift down by lifting off the throttle a few times...” I assume you mean shift up rather than shift down? One reason for the transmission to hold on to the lower gears is...

Sounds like you have a worn rear stator bush. I would check the E-clutch circuit with air pressure, to confirm. https://www.landyzone.co.uk/land-rover/gearbox-speed-sensor.384387/#post-5490737 https://www.landyzone.co.uk/land-rover/help-please-gearbox-issue.330768/#post-4269229 Phil

Could be the output shaft spline which has failed. If the spline isn’t lubricated during assembly then it can fail through fretting corrosion. Common issue on the 6HP26X models, less common on the 6HP28X like yours. Phil

I guess Automatic Transmissions Preston Ltd on Emmanuel Street is the best known in our immediate area. They've been going for donkey's years Phil

If you can record some live data, that may certainly help determine what’s going on. The fewer things you measure, the higher the sampling frequency, so I would suggest just engine speed, turbine speed and output speed initially. The detection of clutch slip and subsequent selection of the next...

I wonder if this is the early signs of a worn rear stator bush. This is a very common issue with the 6HP26 and this bush acts as a seal for the E-clutch hydraulic circuit. When it wears & subsequently leaks, the pressure on the E-clutch drops and the clutch can slip. The transmission control...