Check CAN Bus Line (CAN-H) For Short to GND

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: Check CAN Bus Line (CAN-H) for Short to GND

Check CAN Bus Line (CAN-H) for Short to GND

DESCRIPTION

A short to GND is suspected in the CAN bus wire when the resistance between terminals 4 (CG) and 6 (CANH) of the DLC3 is below 200 Ohms.

WIRING DIAGRAM

INSPECTION PROCEDURE
HINT: Identify the connector to be checked by its color of the wire and shape of the junction on the CAN J/C because the locations of the connectors to the CAN J/C are confusing.

PROCEDURE

1. CHECK CAN BUS WIRE FOR SHORT TO GND (DLC3 BRANCH WIRE, CAN-H)

(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the DLC3 branch wire connector (J25) from the wiring harness connector (CAN J/C1).

NG -- REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR (CAN-H)
OK -- Continue to next step.
2. CHECK CAN BUS WIRE FOR SHORT TO GND (CAN-H)
(a) Reconnect the DLC3 branch wire connector (J25) to the wiring harness connector (CAN J/C1).

(b) Disconnect the connectors from the CAN J/C1 one at a time.
HINT: Disconnect the ECU and sensor connectors other than the DLC3 branch wires and CAN main bus wires between the CAN J/C1 and CAN J/C2.
(c) Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 4 (CG) of the DLC3 each time a connector is disconnected.

HINT:
(*1) : with dynamic laser cruise control system
NOTICE:
Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to GND in 2 or more CAN bus wires.

Result:

(d) When there is a short to GND in one or more of the bus wires that connect to an ECU (or sensor):
(1) Reconnect all of the connectors to the CAN J/C, except for the one that was disconnected last (the bus wire that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ohms or higher) to confirm that there is a short to GND in the one branch wire only.
HINT:
- The connectors connected to the CAN J/C can be distinguished according to the color of the communication bus wires and the shape of the connectors.
- Reconnecting the connectors to non-specified positions on the CAN J/C does not affect system operation. However, it is preferred to reconnect the connectors to their specified positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

B -- CHECK CAN BUS WIRE FOR SHORT TO GND (CAN-H)
A -- Continue to next step.
3. CHECK CAN BUS WIRE FOR SHORT TO GND (CAN MAIN BUS WIRE, CAN-H)

(a) Disconnect the CAN main bus wire connector (J27) from the wiring harness connector (CAN J/C1).

(b) Measure the resistance according to the value in the table below.
Standard resistance:

NG -- REPLACE WIRING HARNESS CONNECTOR (CAN J/C1)
OK -- Continue to next step.
4. CHECK CAN BUS WIRE FOR SHORT TO GND (CAN MAIN BUS WIRE, CAN-H)

(a) Disconnect the CAN main bus wire connector (J43) from the wiring harness connector (CAN J/C2).

(b) Measure the resistance according to the value in the table below.
Standard resistance:

HINT: Confirm disconnection of the CAN main bus wire connector (J27) from the wiring harness connector (CAN J/C1) during the measurement.

NG -- REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (CAN-H)
OK -- REPLACE WIRING HARNESS CONNECTOR (CAN J/C2)
5. CHECK CAN BUS WIRE FOR SHORT TO GND (CAN-H)
(a) Reconnect the connector of the bus wire that is shorted to GND to the CAN J/C (the connector that caused the bus wire resistance to change to 200 Ohms or higher when it was disconnected).
(b) Disconnect the connector that includes terminal CANH from the ECU (or sensor) to which the bus wire shorted to GND is connected. CAN Communication System

HINT: If the resistance changes to 200 Ohms or higher when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR (CAN-H)
OK -- REPLACE CORRESPONDING ECU OR SENSOR