M-MDS AND VEHICLE NOT COMMUNICATING [MULTIPLEX COMMUNICATION SYSTEM (L.H.D.)]

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  Caution
  • Perform the following on-board diagnosis according to FOREWORD [MULTIPLEX COMMUNICATION SYSTEM (L.H.D.)] troubleshooting procedure.

Detection Condition

• Possible causes of communication errors between the M-MDS and vehicle include communication circuit interruption due to an open circuit in the CAN communication wiring harness, or poor contact of connector terminals, or a BUS OFF condition due to a short circuit in the CAN communication wiring harness.

Possible Causes

• Open circuit in wiring harness between PCM and DLC-2
• Improper insertion of PCM, connector C-08, connector C-05, or connector C-11 damage, deformation, corrosion, or disconnection of connector terminals
• Short circuit in wiring harness between CAN system-related module CAN_L and CAN_H lines
• Short circuit to power supply in wiring harness between CAN system-related module
• Short circuit to ground in wiring harness between CAN system-related module
• Short circuit to power supply in CAN system-related module internal CAN lines
• Short circuit to ground in CAN system-related module internal CAN lines
• Damage, deformation, corrosion, or disconnection of DLC-2
• PCM power supply is not normal
• PCM ground is not normal
• PCM internal resistance is not normal
• CAN system-related module malfunction

Wiring Diagram

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Diagnostic Procedure

  Caution
  • When disconnecting the connector, verify that there is no looseness, damage, deformation, corrosion, or poor connection of the connector terminals.

Step | Inspection | Action
--- | --- | ---
1 | VERIFICATION BEFORE SERVICING • Is there communication between the M-MDS and vehicle? | Yes | Go to the next step.
No | Go back to FOREWORD [MULTIPLEX COMMUNICATION SYSTEM]. (See FOREWORD [MULTIPLEX COMMUNICATION SYSTEM (L.H.D.)].)
2 | VERIFY THAT M-MDS AND DLC-2 ARE CONNECTED • Verify the connection condition between the M-MDS and DLC-2. • Are the connector terminals normal without damage, deformation, corrosion, or disconnection? | Yes | Go to the next step.
No | Correct the connection condition, then go to Step 12.
3 | VERIFY PCM POWER SUPPLY CONDITION • Refer to the PCM terminal voltage table and inspect the terminal voltage and fuse condition. (See PCM INSPECTION [L8, LF].) • Is the power supply condition normal? | Yes | Go to the next step.
No | Repair or replace the fuse or wiring harness, then go to Step 12.
4 | VERIFY PCM BODY GROUND CONDITION • Inspect the PCM body ground wiring harness and ground point. • Are the ground and ground point normal? | Yes | Go to the next step.
No | Repair or replace the wiring harness, then go to Step 12.
5 | INSPECT PCM CONNECTOR TERMINAL • Disconnect the negative battery cable. • Disconnect the PCM connector. • Are the PCM connector terminal normal without damage, deformation, corrosion, or disconnection? | Yes | Go to the next step.
No | Repair the connector terminal if necessary, then go to Step 12.
6 | INSPECT PCM • Measure the resistance between the following PCM connector terminals: ― Between terminal 1AM and terminal 1AI (part side) • Is the resistance 118-130 ohms? | Yes | Go to the next step.
No | Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L8, LF].)
7 | VERIFY THAT THERE IS NO OPEN CIRCUIT IN CAN COMMUNICATION WIRING HARNESS Caution • When inspecting the DLC-2, touch it with a paper clip or similar thin pin without directly inserting a tester into the terminals. • Verify the continuity between the following terminals: ― Between DLC-2 terminal F and PCM terminal 1AM ― Between DLC-2 terminal E and PCM terminal 1AI • Is there continuity? | Yes | Go to the next step.
No | There is an open circuit in the CAN communication wiring harness. Repair or replace it, then go to Step 12.
8 | VERIFY THAT THERE IS NO SHORT CIRCUIT IN CAN COMMUNICATION WIRING HARNESS Caution • When inspecting the DLC-2, touch it with a paper clip or similar thin pin without directly inserting a tester into the terminals. • Measure the resistance between the terminals. ― Between DLC-2 terminal F and DLC-2 terminal E • Is the resistance 60 ohms or less? | Yes | There is an open circuit in the CAN communication wiring harness. Repair or replace it, then go to Step 12.
No | Go to the next step.
9 | VERIFY NO SHORT CIRCUIT TO GROUND IN CAN COMMUNICATION WIRING HARNESS Caution • When inspecting the DLC-2, touch it with a paper clip or similar thin pin without directly inserting a tester into the terminals. • Verify the continuity between the following terminals: ― Between DLC-2 terminal F and ground ― Between DLC-2 terminal E and ground ― Between PCM terminal 1AM and ground ― Between PCM terminal 1AI and ground • Is there continuity? | Yes | There is a short circuit to ground in the CAN communication wiring harness. Repair or replace it, then go to Step 12.
No | Go to the next step.
10 | VERIFY NO SHORT CIRCUIT TO POWER SUPPLY SYSTEM IN CAN COMMUNICATION WIRING HARNESS Caution • When inspecting the DLC-2, touch it with a paper clip or similar thin pin without directly inserting a tester into the terminals. • Verify the continuity between the following terminals: ― Between DLC-2 terminal F and DLC-2 terminal A ― Between DLC-2 terminal E and DLC-2 terminal A ― Between PCM terminal 1AM and PCM terminal 1BA ― Between PCM terminal 1AI and PCM terminal 1BA • Is there continuity? | Yes | There is a short circuit to the power supply system in the CAN communication wiring harness. Repair or replace it, then go to Step 12.
No | Go to the next step.
11 | INSPECT CAN-RELATED MODULES OTHER THAN PCM • Remove only one of the CAN-related modules other than those related to the PCM. • Connect the negative battery cable. • Connect the M-MDS to the DLC-2. • Does the M-MDS recognize the vehicle? | Yes | Replace the removed module.
No | Inspect all of the CAN-related modules other than those related to the PCM using the same procedure. After inspecting all of the modules, go to the next step.
12 | PERFORM VEHICLE IDENTIFICATION • Connect the M-MDS to the DLC-2. • Does the M-MDS recognize the vehicle? | Yes | DTC troubleshooting completed.
No | Replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)