Quote:
Originally Posted by roscoea26
Thanks for that Clarky. So from what they are saying the crack in the actuator circuit board traces in a bias (offset) position signal which could be incorrectly interpreted by the FDCM, but doesn't that relate to the neutral issue. I though I read somewhere that this 4x4 low problem is another issue ? I've had a look at my replaced actuator and the build date is 21.10.13 it has 9:37:55AM stamped on it. I would assume that as it was built after the recall in USA that it shouldn't have a cracked circuit board surely that would be the case.
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Clarky's already covered it, but here's a bit more anyway
The N23 update was (according to what has been published.) just an update to the conditions of the C140F code.
Here's the description of the new condition from STAR case;
Quote:
Symptom/Vehicle Issue:
Diagnostic Trouble Code C140F “Transfer Case Range Position Sensor Erratic Performance”
After Performing Recall N23
Discussion:
The Final Drive Control Module (FDCM) monitors the transfer case position sensor for two erratic
performance failures.
1. Position sensor drift to higher voltages during the drive cycle.
2. A difference between the encoder position value detected at first key on cycle compared to the
value stored into memory during the previous key off event.
Either failure mode will result in the setting of a permanent C140F fault. Once set, this fault will
remain active until the 4WD system is repaired. The “Service 4WD” indicator in the instrument cluster
will not illuminate when this fault sets until the customer attempts a range shift (between 4WD High
and 4WD Low, or Neutral).
Diagnosis:
1. Confirm the integrity of the Transfer Case shift motor wiring harness. Any circuit faults present
must be addressed prior to repairing the C140F fault. It is possible that both a C140F (Erratic
Encoder Performance Fault) and a C1405 fault (T-case range position sensor circuit high fault)
may be set due to the failure of the actuator. However, continuity of each circuit and checks
for short to ground and shorted circuit to circuit should be checked for each circuit of the TCase
interface.
2. Replace the actuator on the Transfer Case. Using the diagnostic tool, confirm that the position
sensor reading is 2.84 volts +/- 0.04. (FDCM / Read Write Data).
Parts Required:
AR (1) 05143786AA Actuator, Transfer Case
Repair Procedure:
1. Replace the actuator. Refer to the procedures identified in the appropriate Service Information
for additional information.
2. Perform a key cycle (Key ON and then key OFF). Allow sufficient time for the FDCM and the
entire vehicle bus to go to sleep. To be sure the entire vehicle bus to go to sleep, disconnect
all diagnostic tools from the vehicle, turn off the key, and remove key from the ignition. Close
all doors. Wait 5 minutes.
3. After performing the key cycle, DO NOT attempt to shift the transfer case using the customer
switch. This will prevent the C140F fault from clearing later.
4. Re-connect the diagnostic tool and cycle the key ON.
5. Select the FDCM, and issue the clear faults command two times. It is required to issue the
clear faults command twice.
6. After approximately 6 seconds, the C140F fault will de-mature to a “Stored” status. Confirm
that the diagnostic tool reports that the C140F fault is in a stored status (not “Active”). If after
30 seconds the fault is not in a stored status, return to step 3 and try again.
7. Once the C140F fault is in a stored status, perform one additional “Clear Faults” command.
This will completely remove the fault from the FDCM memory and return the 4WD system to
an operational status.
8. Perform a T-Case range shift to confirm that the 4WD system will shift to 4WD Low Range.
Shift the T-Case back to 4WD High Range. Repair complete. |
I've successfully "tricked" an N23 FDCM (thanks to Clarky.) by placing a small micro-controller between the actuator and the FDCM.
I've tried two different behaviours;
One where it essentially limits the position sensor voltages given to the FDCM to always be within the range accepted by the N23 firmware.
Another where it records the position sensor voltage during key-off, and provides that voltage back to the FDCM during start-up (ignoring the real position sensor voltage.).
I guess we just need to wait for ozjeepster's experience with this latest update?