Thread: 8 speed shift lock solenoid problems

Matt you legend.

Disco Sport MY16 stuck in Drive. NRMA had no idea but I got towed home and used 2 cable ties and a chop stick to retain the plastic locking slide for a temporary fix. I need to buy some tiny torx to remove the circuit board and look for crappy soldering or other issues before I pay $large for a replacement unit.

Thanks again and that PDF is so convenient.

I've shared this post on the UK DS forum and assuming you don't mind.

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The burn mark around the 1 ohm resistor will most likely be due to inadequate heat-sink to dissipate the heat generated by the voltage drop across the resistor which has progressively melted the solder until contact is eventually lost. The resistor will be in the circuit so that voltage drop across it can be measured to detect if the motor is drawing current while operating, whereby no voltage drop would indicate an open circuit for the motor but zero voltage on the motor side would indicate a short to earth, which is the fault being recorded.

I doubt that there were poor solder joints, instead that this resistor requires a better heat-sink which is usually provided either by a larger wattage version of the component that would also have larger contact pads to better dissipate heat into the pcb or at least have larger contact pads. Hence the fault is likely to re-occur in time unless an improved heat-sink is provided. Replacing the resistor with a direct link so as to avoid heat generation would trigger a motor open circuit fault so is not an option.

Edit: Its probably good practice to avoid unnecessarily having the foot-brake applied while the vehicle is in park or neutral so as to reduce the time the shift lock motor is powered and therefore reduce the heat dissipated by that resistor. Shifting to neutral while stopped at traffic lights is an example of excessive powering of the shift lock motor.

Interesting comment re the resister. We found no burn marks on ours and it has been good for many thoussnd of ks since resoldering as per the advice.

Only had one fail when I shifted it from d to r and d again quite quickly which caused it to sieze up...oh **** I thought...but all good after re boot😚

Burn marks would only occur if the joint has been make/break for a while. If it goes high resistance due to becoming a cold solder joint then no arcing, effectively becoming open circuit when under the load of the motor.

Thanks of the detailed info on here, it is very helpful - I have a couple of questions.

Problem: When using the car for more that 20mins the dial gets stuck in Drive and won't move out of Drive - suspect this is the same issue reported in this thread. If I turn the car off the dial retracts and moves to park. When restarting the car, the dial is free to move as it should.

Given the nature of the issue and the fact I tow a large caravan I wanted to resolve asap. I have managed to purchase a used control unit for £100 - so plan to simply exchange the unit.

Do I need to disconnect the battery prior to removing the gear selector unit?

Will I need a code reader to setup the gear selector unit once installed?

Many thanks

Steve

Thank you for the comprehensive guide. I copied what you have done as mine was locking intermittently. Glad I did as the solenoid appears to have packed in altogether. I've been quoted £330 for a new unit. Do you or anyone know if the new part is plug and play or if it would need to be programmed in. Thanks

Originally Posted by rowesa

Thanks of the detailed info on here, it is very helpful - I have a couple of questions.

Problem: When using the car for more that 20mins the dial gets stuck in Drive and won't move out of Drive - suspect this is the same issue reported in this thread. If I turn the car off the dial retracts and moves to park. When restarting the car, the dial is free to move as it should.

Given the nature of the issue and the fact I tow a large caravan I wanted to resolve asap. I have managed to purchase a used control unit for £100 - so plan to simply exchange the unit.

Do I need to disconnect the battery prior to removing the gear selector unit?

Will I need a code reader to setup the gear selector unit once installed?

Many thanks

Steve

Hi Steve, did you have to programme the exchanged unit or is it plug and play. Cheers

Registered for this post specifically. This is a world-class example of helping out others! Fantastic writeup and research. Sincere thanks and yes, we all owe you the beverage of your choice.