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DIAGNOSTIC ITEM 1: Communication with gateway-ECU is not possible [CAN-C (Diag)].
 
 
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 scan tool MB991958 receives data from the gateway-ECU via CAN-C (Diag) line.
 
 
TROUBLE JUDGEMENT CONDITIONS
Scan tool MB991958 judges the trouble when the data from the gateway-ECU cannot be received.
 
 
TROUBLESHOOTING HINTS
  • Damaged harness wires and connectors
  • Malfunction of the gateway-ECU power supply circuit
  • Malfunction of the gateway-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Connector check: gateway-ECU connector C-49 and data link connector C-227
cautionThe strand end of the twist wire should be within 10 cm from the connector. For details refer to .
Is the check result normal?
Go to Step 2.
Repair the defective connector.
 
STEP 2. Continuity check between data link connector C-227 and gateway-ECU connector C-49
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the scan tool MB991958 and gateway-ECU connector C-49 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Check the continuity between data link connector C-227 terminal No. 6 and gateway-ECU connector C-49 terminal No. 29. <CAN_H>
OK: Continuity exists (2 ohms or less)
(5) Check the continuity between data link connector C-227 terminal No. 14 and gateway-ECU connector C-49 terminal No. 28. <CAN_L>
OK: Continuity exists (2 ohms or less)
Is the check result normal?
Go to Step 3.
Repair the wiring harness between the data link connector C-227 and gateway-ECU connector C-49.
 
STEP 3. Resistance measurement at data link connector C-227 (short to ground check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the scan tool MB991958 and gateway-ECU connector C-49 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Measure the resistance between data link connector C-227 terminal No. 6 and body ground. <CAN_H>
OK: 1 kΩ or more
(5) Measure the resistance between data link connector C-227 terminal No. 14 and body ground. <CAN_L>
OK: 1 kΩ or more
Is the check result normal?
Go to Step 4.
Repair the wiring harness between the data link connector C-227 and gateway-ECU connector C-49.
 
STEP 4. Voltage measurement at data link connector C-227 (short to power supply check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the scan tool MB991958 and gateway-ECU connector C-49 and measure at the wiring harness side.
(2) Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(3) Measure the voltage between data link connector C-227 terminal No. 6 and body ground. <CAN_H>
OK: 1.0 volt or less
(4) Measure the voltage between data link connector C-227 terminal No. 14 and body ground. <CAN_L>
OK: 1.0 volt or less
Is the check result normal?
Go to Step 5.
Repair the wiring harness between the data link connector C-227 and gateway-ECU connector C-49.
 
STEP 5. Resistance measurement at data link connector C-227 (line-to-line short check)
caution
  • A digital multimeter should be used. For details refer to .
  • The test wiring harness should be used. For details refer to .
  • When measuring the resistance, disconnect the negative battery terminal. For details refer to .
  • Strictly observe the specified wiring harness repair procedure. For details refer to .
(1) Disconnect the scan tool MB991958 and gateway-ECU connector C-49 and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Ensure that the negative battery terminal is disconnected.
(4) Measure the resistance between data link connector C-227 terminal Nos. 6 and 14.
OK: 1 kΩ or more
Is the check result normal?
Go to Step 6.
Repair the wiring harness between the data link connector C-227 and gateway-ECU connector C-49.
 
STEP 6. Resistance measurement at gateway-ECU connector C-49
cautionA digital multimeter should be used. For details refer to .
(1) Remove the gateway-ECU, and measure at the equipment side.
(2) Measure the resistance between gateway-ECU connector C-49 terminal Nos. 28 and 29.
OK: 60 ± 10 ohms
Is the check result normal?
<Within 60 ± 10 ohms> Power supply to the gateway-ECU may be suspected (Refer to ).
<Not within 60 ± 10 ohms> Replace the gateway-ECU (Refer to ).