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Diagnostic Item 30: Diagnose when the scan tool cannot receive the data sent by engine control module (ECM).
 
 
cautionWhen servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.
 
 
FUNCTION
The diagnostic result demonstrates that "the scan tool (M.U.T.-IIISE) cannot receive the sent data from the engine control module (ECM)" when the scan tool (M.U.T.-IIISE) checks the periodically sent data from each ECU and cannot receive the ECM data only.
 
 
TROUBLE JUDGMENT CONDITIONS
Scan tool (M.U.T.-IIISE) judges the trouble when the periodically sent data from ECM cannot be received.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Power supply circuit malfunction of the ECM
  • Malfunction of the ECM
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: joint connector (CAN1) <Vehicles without ACC>, joint connector (CAN2) and ECM connector.
cautionThe strand end of the twist wire should be within 10 cm (4 inches) from the connector. For details refer to .
When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.
Is the check result normal?
Go to Step 2.
Repair the defective connector. Replace the joint connector as necessary.
 
STEP 2. Resistance measurement at joint connector (CAN2) and ECM connector.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect the joint connector (CAN2) and the ECM connector, and measure at the wiring harness side.
(2) Turn off the power supply mode of the electric motor switch.
(3)
cautionWhen measuring the resistance, disconnect the negative 12V starter battery terminal. For details refer to .
Ensure that the negative 12V starter battery terminal is disconnected.
(4) Continuity between joint connector (CAN2) terminal No.2 and ECM connector terminal No.90
OK: Continuity (2 ohms or less)
(5) Continuity between joint connector (CAN2) terminal No.13 and ECM connector terminal No.91
OK: Continuity (2 ohms or less)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
Is the check result normal?
: <All the resistances measure 2 ohms or less> Go to Step 3.
: <All the resistances measure 2 ohms or less> Go to Step 4.
: <Either or all of the resistances measure more than 2 ohms> Repair the wiring harness between joint connector (CAN2) and the ECM.
 
STEP 3. Resistance measurement at joint connector (CAN1) and joint connector (CAN2) connector.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Disconnect the joint connector (CAN1) and the joint connector (CAN2), and measure at the wiring harness side.
(2) Turn off the power supply mode of the electric motor switch.
(3)
cautionWhen measuring the resistance, disconnect the negative 12V starter battery terminal. For details refer to .
Ensure that the negative 12V starter battery terminal is disconnected.
(4) Continuity between joint connector (CAN1) terminal No.2 and joint connector (CAN2) terminal No.1
OK: Continuity (2 ohms or less)
(5) Continuity between joint connector (CAN1) terminal No.11 and joint connector (CAN2) terminal No.12
OK: Continuity (2 ohms or less)
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
Is the check result normal?
<All the resistances measure 2 ohms or less> Go to Step 4.
: <Either or all of the resistances measure more than 2 ohms> Repair the wiring harness between joint connector (CAN1) and the joint connector (CAN2).
 
STEP 4. Resistance measurement at ECM connector.
cautionA digital multimeter should be used. For details refer to .
(1) Remove the ECM, and measure at the equipment side.
(2) Resistance between ECM connector terminal Nos.90 and 91
OK: 120 ± 20 ohms
cautionStrictly observe the specified wiring harness repair procedure. For details refer to .
Is the check result normal?
<Within 120 ± 20 ohms> Power supply to the ECM may be suspected. Diagnose the fuel system. Refer to GROUP 13A - Troubleshooting .
<Not within 120 ± 20 ohms> Replace the ECM.