[Previous][Next]
Diagnostic Item 27: 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.-III) cannot receive the sent data from the engine control module (ECM)" when the scan tool (M.U.T.-III) checks the periodically sent data from each ECU and cannot receive the ECM data only.
 
 
TROUBLE JUDGMENT CONDITIONS
Scan tool (M.U.T.-III) 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
STEP 1. Connector check: joint connector (CAN1) <Vehicles without ACC> or joint connector (CAN2) <Vehicles with ACC> and ECM connector
cautionThe strand end of the twist wire should be within 10 cm 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 (CAN1) <Vehicles without ACC> or joint connector (CAN2) <Vehicles with ACC> 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 (CAN1) <Vehicles without ACC> or joint connector (CAN2) <Vehicles with ACC> and the ECM connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the LOCK (OFF) position.
(3)
cautionWhen measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.
(4) Continuity between joint connector (CAN1) terminal No.8 and ECM connector terminal No.90 <Vehicles without ACC>
OK: Continuity (2 ohms or less)
(5) Continuity between joint connector (CAN1) terminal No.17 and ECM connector terminal No.91 <Vehicles without ACC>
OK: Continuity (2 ohms or less)
(6) Continuity between joint connector (CAN2) terminal No.10 and ECM connector terminal No.90 <Vehicles with ACC>
OK: Continuity (2 ohms or less)
(7) Continuity between joint connector (CAN2) terminal No.21 and ECM connector terminal No.91 <Vehicles with ACC>
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.
: <Either or all of the resistances measure more than 2 ohms> Repair the wiring harness between joint connector (CAN1) <Vehicles without ACC> or joint connector (CAN2) <Vehicles with ACC> and the ECM.
 
STEP 3. 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 <4J1>, GROUP 13B - Troubleshooting <6B3>)
<Not within 120 ± 20 ohms> Replace the ECM.