Transmission CAN Replacement D3

[tadpole]

My 07 D3 has 190k on the clock and drops into limp home mode every 100 metres or so. Based on information gleaned from this forum the culprit could be the transmission control unit since the error messages were the same (Transmission error, HDC not available, Park Brake fault, Vehicle lowered) so I removed the unit and found a small amount of corrosion in the middle connector. I cleaned out the corrosion and everything was fine but lasted just 20kms before failing again, and again, and again then it returned to normal operation. However I am reluctant to risk driving more than a few Kms from home and have decided to replace the transmission CAN.
Does anyone know if the new unit will need to be programmed after installation?

[loanrangie]

Those errors also come up with low battery, charging fault and brake switch fault.

[Graeme]

What do you mean by the transmission CAN and transmission control unit? The transmission control unit is inside the transmission, only accessible after removing the gearbox sump and control valves.

[tadpole]

Those errors also come up with low battery, charging fault and brake switch fault.

Th battery should not be a problem since I connect main and aux batteries together when driving around suburbs and only separate when on a trip. The alternator is less than two years old and I changed the brake light switch about 6 months ago, both jobs done as preventive maintenance. Alternator voltage is14.8v
I appreciate your input but think I have those potential problems covered.

[tadpole]

What do you mean by the transmission CAN and transmission control unit? The transmission control unit is inside the transmission, only accessible after removing the gearbox sump and control valves.

Hi Graeme,
The transmission "CAN" referred to is located behind the main battery on the D3 so I may have misused the terminology. The part number is NNW512070 and a replacement is on order.
My question related to this item and if anyone knows whether a replacement unit would need re-calibration. If recalibation is necessary is it possible to drive the vehicle any distance or will I need to have the vehicle trucked to a service centre.
Any help with this would be welcomed

[Graeme]

Transfer case control module (TCCM)! That is very unlikely to be the cause of your problems and if replaced then yes it has to be calibrated. If the TCCM fails then lots of canbus communications faults for modules on the high speed canbus will be reported - heaps of them, because the module is a HS canbus gateway between essential and non-essential modules on the bus.

The vehicle lowering will be because the suspension ecu will lower the car to access height for almost any brake system fault reported on the HS canbus. However as already suggested, low battery voltage could be the cause of the transmission, HDC and park brake faults if the voltage doesn't meet the minimum voltage for the gearbox and ABS modules, so you need to verify that battery voltage is OK. If OK then the external radio noise suppression capacitor mounted under the gearbox may have gone short circuit (they fail with age) causing excessive current draw from the gearbox supply - it can be removed to check if the problem is cured.

Real HDC faults would normally be caused by a faulty wheel speed sensor. However as HDC requires significant current to operate the ABS modulator and that the gearbox requires significant current to operate its solenoids and the park brake requires significant current to operate, I urge you to be very certain that battery voltage is up to scratch as a priority.

[tadpole]

Hi Graeme. Thank you ....... and wow for all the information.
I will carefully revisit all of the items you have mentioned to see if any are the culprit(s) and report back. Fortunately I don't need to drive very far to get a result!!

[tadpole]

Hi Graeme. I checked the battery voltage (12.2v) and the charging (14.1v) so both are OK and should not be cause of problem. I then checked the radio suppression capacitor but nothing untoward visible but I did find damage to the insulation on a wire entering another component. The small black plastic component attached to the cross member at rear of gearbox with two wires (a black one and the other white with pale blue). Insulation on the black wire is damaged. Don't know what this component does but damaged wire could potentially short out.
Having done nothing except poke at the capacitor I went for a long drive and vehicle behaved as normal. I have now taped the wires on the (??) component and will see if this fixes the problem longer term.
In view of vehicle performing normal I will change the suppression capacitor just to be safe. The capacitor is in a stupid location given all the space available on the outside of the gearbox..

Thank you for your advice. I will not proceed replacing the TCCM

[Graeme]

Hopefully you've found the culprit although black wires are usually for earth so its worn insulation might not have been the cause. I don't know the component but will try to identify it from your description and wire colours.

The spare TCCM wont go astray as they too easily succumb to water ingress, being unsealed.

[DazzaTD5]

As partly mentioned... if you mean Transfer Case Control Module, the small allum box behind battery (first computer in position, if you will)
*Graeme has covered it well, but errors are dependent on what component is failing on the TCCM.
*You need to remove it, pull it apart and inspect the printed circuit board, odds are there will be corrosion on the board, if so, it will need to be replaced.
*Before the new one is fitted, pull it apart and spray the board with some protective circuit board lacquer and put allum case back together using auto grade sealant, seal around rubber boots to the plastic cover, then spray the lot with some silicone spray.
*Again as Graeme has said, it needs to be calibrated to function, BUT vehicle can be driven to workshop for calibration (if when it was removed it was in high range (for normal driving)) and the shifter in sport mode can be used like a manual trans (without a clutch).