Diagnostic Item 17
DIAGNOSTIC ITEM 17: Diagnose the lines between CAN main bus line and the powertrain control moduleCAUTION: When servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do so, a component connected to the CAN bus line may be damaged.
TROUBLE JUDGMENT
If the M.U.T.-III cannot received signals from the powertrain control module, CAN bus line connector(s) are broken or an open circuit has occurred.
COMMENTS ON TROUBLE SYMPTOM
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the powertrain control module may be defective.
TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector
- The powertrain control module may be defective
DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set
STEP 1. Check intermediate connector C-29 and powertrain control module connector B-19 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Q: Are intermediate connector C-29 and powertrain control module connector B-19 in good condition?
YES: Go to Step 2.
NO: Repair the damaged parts. Replace the joint connector as necessary.
STEP 2. Check the CAN bus lines between intermediate connector C-29 and the powertrain control module. Measure the resistance between intermediate connector C-29 and powertrain control module connector B-19.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect intermediate connector C-29 and powertrain control module connector B-19, and measure the resistance between the wiring harness side connector of powertrain control module connector B-19 and the male side connector of intermediate connector C-29 (at front wiring harness side).
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between intermediate connector terminal 11 and powertrain control module connector terminal 17.
OK: 2 ohms or less
5. Measure the resistance between intermediate connector terminal 12 and powertrain control module connector terminal 18.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, go to Step 3.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness between intermediate connector C-29 and the powertrain control module connector.
STEP 3. Check joint connector (3) C-02 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector.
Check the joint connector at the wiring harness side for loose, corroded or damaged terminals, or terminals pushed back in the connector, and also check the short pin behind the connector for corrosion, deformation and delamination.
Q: Is joint connector (3) C-02 in good condition?
YES: Go to Step 4.
NO: Repair the damaged parts. Replace the joint connector as necessary.
STEP 4. Check the CAN bus lines between intermediate connector C-29 and the joint connector (3). Measure the resistance between intermediate connector C-29 and joint connector (3) C-02.
CAUTION: A digital multimeter should be used.
CAUTION: The test wiring harness should be used.
1. Disconnect joint connector (3) C-02 and intermediate connector C-29, and measure the resistance between the wiring harness side connector of joint connector (3) C-02 and the female side connector of intermediate connector C-29 (instrument panel wiring harness side).
2. Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION: Disconnect the negative battery terminal.
3. Disconnect the negative battery terminal.
4. Measure the resistance between intermediate connector terminal 12 and joint connector (3) terminal 20.
OK: 2 ohms or less
5. Measure the resistance between intermediate connector terminal 11 and joint connector (3) terminal 9.
OK: 2 ohms or less
CAUTION: Strictly observe the specified wiring harness repair procedure.
Q: Do all the resistances measure 2 ohms or less?
YES: If all the resistances measure 2 ohms or less, power supply to the powertrain control module may be suspected. Diagnose the engine. Refer to MFI, MFI diagnosis <2.4L engine> or MFI diagnosis <3.8L engine>.
NO: If either of the resistances measures more than 2 ohms or all the resistances measure more than 2 ohms, repair the wiring harness wires between intermediate connector C-29 and joint connector (3).