Thread: A Different Transmission Fault

You are correct Graeme, I'm getting my ECUs mixed up. What I should have written is that the CAN connections to the Transfer case ECU are prone to getting wet and corrosion can occur.

The detail below is from the manual. I have seen problems with ones in red. I usually see transmission fault, HDC unavailable, Park brake faults and sometimes suspension faults. I suspect if I try to select low range I would get an error as well.

CONTROLLER AREA NETWORK (CAN)
The high speed CAN broadcast bus network is used to connect the powertrain modules. The CAN bus is connected
between the following electronic units:
High Speed CAN Bus
�� TCM (Transmission Control Module)
�� Instrument cluster
�� Air suspension module
�� Steering angle sensor
�� Rear differential module
�� Centre console switch pack
�� Electric park brake module
�� Restraints control module
�� Engine Control Module (ECM)
�� ABS control module (HDC faults)
�� Adaptive front lighting control module
�� Transfer box control module
�� Adaptive cruise control module
�� Diagnostic socket.
The CAN bus allows a fast exchange of data between modules. The CAN bus comprises two wires which are identified as
CAN high (H) and CAN low (L). The two wires are coloured yellow/black (H) and yellow/brown (L) and are twisted
together to minimise electromagnetic interference (noise) produced by the CAN bus messages. For additional information,
refer to Communications Network (418-00 )
In the event of CAN bus failure, the following symptoms may be observed:
�� Transmission operates in default mode
�� Torque converter lock-up clutch control is disabled
�� Gear position indication in instrument cluster message centre inoperative (this will also occur with any
transmission fault).

The TC module and its connector not being sealed is a weak point in the general water-proof connections everywhere else where water can reasonably be expected to get. The suspension ecu's connectors aren't sealed either but water doesn't usually get inside the cabin.

Originally Posted by Geedublya

You are correct Graeme, I'm getting my ECUs mixed up. What I should have written is that the CAN connections to the Transfer case ECU are prone to getting wet and corrosion can occur.

In the event of CAN bus failure, the following symptoms may be observed:
�� Transmission operates in default mode
�� Torque converter lock-up clutch control is disabled
�� Gear position indication in instrument cluster message centre inoperative (this will also occur with any
transmission fault).

This is the exact fault I am getting. Has happened twice, the last time was two weeks ago. Whereabouts is the TC ECU on these cars? Near the battery? What should I be looking for?

Rich, those faults might only involve the gearbox wiring, not necessarily the HS canbus or any other ecu connected to it. Anyway, the transfer case module in the D4 is located forward of the brake booster and I understand the D3's is in the same place.

D3 is mounted behind the battery from what I understand.

Yes, if you are only getting one fault it is probably the gearbox or connection to it.