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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21634
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 2002 2.7 CRD automatic. Gear selection has failed.

Resolved Question:

I have a 2002 2.7 CRD automatic. Gear selection has failed. It seems the fault may lie in the transfer box because the problem has arisen three times I have come out of low ratio. sometimes the gearbox engages when the transfer leaver is half way between N and 4 All Time. The vehicle is permanent FWD. the main gearbox works well when engaged although there is a tendency for it to stick in first gear after takeoff when cold. The vehicle has 106k miles. Little enough for a Mercedes drive chain.
Any ideas, or do I just scrap the thing?
Submitted: 1 year ago.
Category: Car
Expert:  Matt replied 1 year ago.
hello If you haven't already then I'd take a look at the colour of the transmission oil it should be a dark red colour if its black then its needs changing together with its oil filter. Also check its level with the gearbox warm and just after you've moved the selector through all the positions leaving it for a few seconds in each one and then back to park. You can top up the box through the side fill plug if required and make sure you use the correct oil for your car as the fluids are not all the same. Some manufacturers recommended a change of the type of fluid - Speak to the local dealer and parts dept - they will advise you on the updated fluid to use.. If that’s all OK then check all the electrical connections of the gearbox, remove each connector in turn and spray with contact cleaner. Check that the wiring to the gearbox is in good condition with no chafing or frayed wire If this is OK then check the selector lever linkage / cable under the car for any broken parts and or missing bolts as if this is coming adrift then it can rub on the car body or just bind up Then - you should top up if low and re try it - or, if its level is ok - and condition is ok - then the next step is to drain it off - open it up and clean the filters inside -- refill and retry it..
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Customer: replied 1 year ago.
I had covered all the bases you mention. The car has gone into Limp mode, showing a fault code of P0702...I got that by using the on/off facility on the dashboard. It didn't show any other faults, which would need a full diagnostic check. It seems to me that the PCB under the gear/transfer box levers may have gone. I'll take the vehicle in for a diagnostic check.
If it is the PCB - and it seems it probably is - do you have any tips for changing it without using OEM spares which run at about £500 or more?
By the way, on full lock, there is a heavy cadence just like a CV joint going. Is this related to the transfer and gearbox problem do you think. If it is a separate problem, the cost would not be worth bearing and I'll scrap the car. Pity because it has only 106k miles on the clock and it is my workhorse - even retired people need one of those!