Diagnostic Item 10

DIAGNOSTIC ITEM 10: Diagnose when the scan tool cannot receive the data sent by the ECM [M/T] or the PCM [A/T].

CAUTION: 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.

Part 1:

Part 2:

FUNCTION
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM [M/T] or PCM [A/T]" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the ECM [M/T] or PCM [A/T] data only.

TROUBLE JUDGEMENT CONDITIONS
Scan tool MB991958 judges the trouble when the periodically sent data from the ECM [M/T] or PCM [A/T] cannot be received and sent.

TROUBLESHOOTING HINTS
- The wiring harness may be defective (open circuit between ABS-ECU [vehicles without TCL or ASC] or ABS/TCL-ECU [vehicles with TCL] or TCL/ASC-ECU [vehicles with ASC] and ECM [M/T] or PCM [A/T])
- The connector may be defective (poor connection of ECM [M/T] or PCM [A/T] connector and ABS-ECU [vehicles without TCL or ASC] or ABS/TCL-ECU [vehicles with TCL] or TCL/ASC-ECU [vehicles with ASC] connector)
- Power supply circuit malfunction of the ECM [M/T] or PCM [A/T]
- The ECM [M/T] or PCM [A/T] may be defective

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra fine probe
- MB991970: ABS Check Harness

STEP 1. Check ABS-ECU connector A-02 [vehicles without TCL or ASC] or ABS/TCL-ECU connector A-03 [vehicles with TCL] or TCL/ASC-ECU connector A-38 [vehicles with ASC] and ECM connector [M/T] or PCM connector [A/T] B-18 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 (4.0 inches) from the connector.

Q: Are ABS-ECU connector A-02 [vehicles without TCL or ASC] or ABS/TCL-ECU connector A-03 [vehicles with TCL] or TCL/ASC-ECU connector A-38 [vehicles with ASC] and ECM connector [M/T] or PCM connector [A/T] B-18 in good condition?

YES : Go to Step 2.

NO : Repair the damaged parts.

STEP 2. Check the CAN bus lines between the ABS-ECU [vehicles without TCL or ASC] or ABS/TCL-ECU [vehicles with TCL] or TCL/ASC-ECU [vehicles with ASC] and the ECM [M/T] or PCM [A/T]. Measure the resistance between ABS-ECU connector A-02 [vehicles with traction control system] or ABS/TCL-ECU connector [vehicles with traction control system] and ECM connector [M/T] or PCM connector [A/T] B-18.

CAUTION:
- A digital multimeter should be used.
- The test wiring harness should be used.

1. Disconnect ABS-ECU connector A-02 [vehicles without TCL or ASC] or ABS/TCL-ECU connector A-03 [vehicles with TCL] or TCL/ASC-ECU connector A-38 [vehicles with ASC] and ECM [M/T] or PCM connector [A/T] B-18, and measure the resistance between each wiring harness side connector.

2. Measure the resistance between ABS-ECU connector [vehicles without TCL or ASC] A-02 (terminal 4) and ECM connector [M/T] or PCM connector [A/T] B-18 (terminal 17).

OK: 2 ohms or less

3. Measure the resistance between ABS-ECU connector [vehicles without TCL or ASC] A-02 (terminal 6) and ECM connector [M/T] or PCM connector [A/T] B-18 (terminal 18).

OK: 2 ohms or less

4. Measure the resistance between ABS/TCL-ECU connector [vehicles with TCL] A-03 (terminal 11) and ECM connector [M/T] or PCM connector [A/T] B-18 (terminal 17).

OK: 2 ohms or less

5. Measure the resistance between ABS/TCL-ECU connector [vehicles with traction control system] A-03 (terminal 15) and ECM connector [M/T] or PCM connector [A/T] B-18 (terminal 18).

OK: 2 ohms or less

6. Measure the resistance between TCL/ASC-ECU connector [vehicles with ASC] A-38 (terminal 11) and ECM connector [M/T] or PCM connector [A/T] B-18 (terminal 17).

OK: 2 ohms or less

7. Measure the resistance between TCL/ASC-ECU connector [vehicles with ASC] A-38 (terminal 15) and ECM connector [M/T] or PCM connector [A/T] B-18 (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 : Diagnose the engine. Refer to MFI diagnosis [2.4L engine] or MFI diagnosis [3.8L engine].

NO : Repair the wiring harness between the ABS-ECU [vehicles without TCL or ASC] connector A-02 or ABS/TCL-ECU [vehicles with TCL] connector A-03 or TCL/ASC-ECU [vehicles with ASC] connector A-38 and the ECM connector [M/T] or PCM connector [A/T] B-18.