Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC C1608: Implausible diagnosis data: Diagnosis
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to STEP 3.
NO: Repair the CAN bus lines. (Refer to CAN BUS DIAGNOSTICS TABLE .) On completion, go to Step 2.
- STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C1608 set?
YES: Go to Step 3.
NO: The procedure is complete.
- STEP 3. Battery check
Refer to BATTERY TEST .
Q: Is the battery in good condition?
YES: Go to STEP 5.
NO: Go to Step 4.
- STEP 4. Charging system check
Refer to OUTPUT CURRENT TEST .
Q: Is the charging system in good condition?
YES: Replace the battery. Then go to STEP 9.
NO: Repair or replace the charging system component(s).
- STEP 5. Voltage measurement at the A-01 ABS-ECU connector
- Disconnect the connector, connect special tool MB991974 to the harness-side connector, and measure the voltage at the special tool connector side.NOTE: Do not connect the special tool MB991974 to ABS-ECU.
- Turn the ignition switch to the ON position.
- Measure the voltage between the terminal No. 26 and the body ground.
OK: 12 volts (Battery voltage)
Q: Is the check result normal?
YES: Go to Step 6.
NO: Go to STEP 7.
- Disconnect the connector, connect special tool MB991974 to the harness-side connector, and measure the voltage at the special tool connector side.
- STEP 6. Connector check: A-01 ABS-ECU connector
Q: Is the check result normal?
YES: The open or short circuit may be present in the power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No. 26 and the fusible link No. 27.
NO: Repair the defective connector.
- STEP 7. Resistance measurement at A-01 ABS-ECU connector
- Disconnect the connector, connect special tool MB991974 to the harness-side connector, and measure the voltage at the special tool connector side.NOTE: Do not connect the special tool MB991974 to ABS-ECU.
- Resistance between the terminal No. 1 and the body ground
OK: Continuity exists (2 ohms or less)
Q: Is the check result normal?
YES: Go to STEP 9.
NO: Go to Step 8.
- Disconnect the connector, connect special tool MB991974 to the harness-side connector, and measure the voltage at the special tool connector side.
- STEP 8. Connector check: A-01 ABS-ECU connector
Q: Is the check result normal?
YES: An open circuit may be present in the ground circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No.14 and the body ground.
NO: Repair the defective connector.
- STEP 9. Check whether the diagnostic Trouble code is reset.
- Erase the diagnostic trouble code.
- Turn the ignition switch to the "LOCK" (OFF) position.
- Turn the ignition switch to the "ON" position.
Q: Is any DTC set?
YES (DTC C1608 is set): Replace the ABS-ECU.
YES (DTC other than C1608 is set): Carry out the applicable troubleshooting for the diagnostic trouble code.
NO: This diagnosis is complete.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.