Diagnostic Item 5

DIAGNOSTIC ITEM 5: Diagnose shorts in the power supply to CAN-C bus line.

CAN Communication Circuit (Part 1):

CAN Communication Circuit (Part 2):

FUNCTION
If a short to power supply is present in the CAN-C lines, this diagnosis result will be set.

TROUBLE JUDGEMENT CONDITIONS
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or an ECU may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the connector (short to power supply in connector)
- Malfunction of the wiring harness (short to power supply in the CAN-C main or sub bus lines)
- Malfunction of the ECU (ETACS-ECU, or ECUs on CAN-C lines failed)

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- 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. Check the wiring harness between joint connector (CAN2) C-05 and ETACS-ECU connector C-301 for a short to power supply. Measure the voltage at joint connector (CAN2) C-05.

1. Disconnect joint connector (CAN2), and measure the voltage at the wiring harness side of joint connector (CAN2).
2. Turn the ignition switch to the ON position.

3. Measure the voltage between joint connector (CAN2) terminal 6 and body ground.

OK: 4.7 volts or less

4. Measure the voltage between joint connector (CAN2) terminal 19 and body ground.

OK: 4.7 volts or less

Q: Do all the voltages measure 4.7 volts or less?

YES : Go to Step 2.

NO : Go to Step 5.

STEP 2. Check the wiring harness between joint connector (CAN3) C-124 and ECM connector B-109 for a short to power supply. Measure the voltage at joint connector (CAN3) C-124.

1. Disconnect joint connector (CAN3), and measure the voltage at the wiring harness side of joint connector (CAN3).
2. Turn the ignition switch to the ON position.

3. Measure the voltage between joint connector (CAN3) terminal 4 and body ground.

OK:4.7 volts or less

4. Measure the voltage between joint connector (CAN3) terminal 15 and body ground.

OK: 4.7 volts or less

Q: Do all the voltages measure 4.7 volts or less?

YES : Go to Step 3.

NO : Go to Step 6.

STEP 3. Check the wiring harness between joint connector (CAN3) C-124 and ABS-ECU connector A-01 for a short to power supply. Measure the voltage at joint connector (CAN3) C-124.

1. Disconnect joint connector (CAN3), and measure the voltage at the wiring harness side of joint connector (CAN3).
2. Turn the ignition switch to the ON position.

3. Measure the voltage between joint connector (CAN3) terminal 6 and body ground.

OK: 4.7 volts or less

4. Measure the voltage between joint connector (CAN3) terminal 19 and body ground.

OK: 4.7 volts or less

Q: Do all the voltages measure 4.7 volts or less?

YES : Check intermediate connector C-128, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) C-05 and joint connector (CAN3) C-124.

YES : Go to Step 4.

NO (the check result is not normal.) : Go to Step 7.

STEP 4. Check the wiring harness between joint connector (CAN3) C-124 and TCM connector C-41 for a short to power supply. Measure the voltage at joint connector (CAN3) C-124.

1. Disconnect joint connector (CAN3), and measure the voltage at the wiring harness side of joint connector (CAN3).
2. Turn the ignition switch to the ON position.

3. Measure the voltage between joint connector (CAN3) terminal 7 and body ground.

OK: 4.7 volts or less

4. Measure the voltage between joint connector (CAN3) terminal 20 and body ground.

OK: 4.7 volts or less

Q: Do all the voltages measure 4.7 volts or less?

YES : Check intermediate connector C-128, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) C-05 and joint connector (CAN3) C-124.

NO : Go to Step 8.

STEP 5. Using scan tool MB991958, diagnose the CAN bus line. (checking the ETACS-ECU for internal short to ground)

CAUTION:
- Strictly observe the specified wiring harness repair procedure.
- To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Disconnect ETACS-ECU connector C-301.
2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.

4. Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.

OK: The display of the scan tool MB991958 is as shown in the figure.

Q: Does scan tool MB991958 screen correspond to the illustration?

YES : Repair the wiring harness between ETACS-ECU connector C-301 and joint connector (CAN2) C-05.

NO : Check ETACS-ECU connector C-128, and repair if necessary. If the ETACS-ECU connector is in good condition, replace the ETACS-ECU.

STEP 6. Using scan tool MB991958, diagnose the CAN bus line. (checking the ECM for internal short to ground)

CAUTION:
- Strictly observe the specified wiring harness repair procedure.
- To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Disconnect ECM connector B-109.
2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.

4. Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.

OK: The display of the scan tool MB991958 is as shown in the figure.

Q: Does scan tool MB991958 screen correspond to the illustration?

YES : Repair the wiring harness between ECM connector B-109 and joint connector (CAN3) C-124.

NO : Check ECM connector B-109, and repair if necessary. If the ECM connector is in good condition, replace the ECM.

STEP 7. Using scan tool MB991958, diagnose the CAN bus line. (checking the ABS-ECU for internal short to ground)

CAUTION:
- Strictly observe the specified wiring harness repair procedure.
- To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Disconnect ABS-ECU connector A-01.

2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.

4. Diagnose CAN bus lines, and check if the scan tool MB991958 screen is as shown in the figure.

OK: The display of the scan tool MB991958 is as shown in the figure.

Q: Does scan tool MB991958 screen correspond to the illustration?

YES : Repair the wiring harness between ABS-ECU connector A-01 and joint connector (CAN3) C-124
NO : Check ABS-ECU connector A-01, and repair if necessary. If the ABS-ECU connector is in good condition, replace the ABS-ECU.

STEP 8. Using scan tool MB991958, diagnose the CAN bus line. (checking the TCM for internal short to ground)

CAUTION:
- Strictly observe the specified wiring harness repair procedure.
- To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Disconnect TCM connector C-41.

2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.