Code No. C1294:
Abnormal rear differential lock detection circuit
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- If there is any
problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis,
diagnose the CAN bus lines (Refer to GROUP 54C - Troubleshooting
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit assembly (integrated with ABS-ECU) is replaced, always carry
out the calibration of and the G sensor (Refer to ).
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OPERATION
The rear differential lock detection switch output signal is sent to ABS-ECU via the CAN
bus lines from transfer-ECU.
DIAGNOSIS CODE SET CONDITION
This diagnosis code will be set when the transfer-ECU detects a fault in the rear differential
lock system.
PROBABLE CAUSES
Current trouble
- The CAN bus line is defective.
- Malfunction of rear differential lock detection switch
- Malfunction of differential carrier assembly
- Malfunction of the transfer-ECU
- Malfunction of the hydraulic unit assembly (integrated with ABS-ECU)
Past trouble
- Carry out diagnosis with particular emphasis on wiring harness and
connector failures between ABS-ECU and the transfer-ECU. For diagnosis procedures, refer to
How to treat past trouble (GROUP 00 - How to Use Troubleshooting/Inspection
Service Points).
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 3.
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 Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Check again if the diagnosis code is set.
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(1)Turn the ignition switch to the "LOCK" (OFF) position.
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(2)Turn the ignition switch to the "ON" position.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Turn the rear differential lock switch to the "ON" position.
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(7)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. C1294 set?
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Go to Step 3.
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions).
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STEP 3. Use M.U.T.-III to confirm a diagnosis code of other systems.
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Check if the diagnosis code is set in the transfer-ECU (Refer to GROUP 23A - Diagnosis
Code Chart).
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Q.
Is the diagnosis code set?
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Troubleshoot the transfer-ECU diagnosis code. Then go to Step 5.
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Go to Step 4.
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STEP 4. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Turn the ignition switch to the "LOCK" (OFF) position.
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(2)Turn the ignition switch to the "ON" position.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Check if the diagnosis code is set.
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Q.
Is code No. C1294 set?
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Replace the hydraulic unit assembly (integrated with ABS-ECU).
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O : Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions).
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STEP 5. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Turn the ignition switch to the "LOCK" (OFF) position.
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(2)Turn the ignition switch to the "ON" position.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. C1294 set?
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Replace the hydraulic unit assembly (integrated with ABS-ECU).
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The procedure is complete.
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