Troubleshooting for Communication Bus Off

Troubleshooting for Communication Bus Off

Wiring Diagram

Refer to CAN Communication System Circuit Diagram CAN Communication System Circuit Diagram.

Diagnosis Procedure

NOTE:

Before executing items in this flow, be sure to perform Initial Inspection and Diagnostic Overview CAN Communication System Check.

When "CAN Communication Bus Off" is detected in any control modules, or when it is not possible to communicate with any control modules by using SUZUKI scan tool (SUZUKI SDT), perform inspection using the following procedure.
1) Connect SUZUKI scan tool (SUZUKI SDT) and have DTC of ECM displayed to check for communication with ECM. If scan tool fails to communicate with ECM, check SUZUKI scan tool and communication cable, DLC power and ground circuit.

If communication is in good condition, proceed on to next Step.
2) Using oscilloscope or oscilloscope function of SUZUKI scan tool (SUZUKI SDT), observe both CAN High terminal (1) and CAN Low terminal (2) for CAN communication signal waveform at DLC on the following condition when ignition switch is at ON position.
Measuring condition

3) Compare observed signal waveform and waveforms given as Reference Waveform. Find the most similar signal waveform and identify the trouble system and trouble nature of the applicable "Reference Waveform".
4) Based on identified trouble system and trouble nature, perform troubleshooting according to Troubleshooting (Advanced Air Bag Model) or Troubleshooting (Non-Advanced Air Bag Model).

Reference Waveform

NOTE:

- Shown below are waveforms observed with oscilloscope function of SUZUKI scan tool (SUZUKI-SDT) as examples for reference.
- Waveforms in "Examples of abnormal waveforms" are picked up as samples among CAN communication waveforms during occurrence of abnormality. However, the same waveform cannot necessarily be observed. Therefore, to identify the content of abnormality, select a waveform which is the most similar to the observed waveform from Examples of abnormal waveforms.

Normal waveform

Reference voltage is 2.5 V (1) for both CAN High signal (2) and CAN Low signal (3).

Waveform of CAN High signal is 2.5 - 3.5 V and that of CAN Low signal is 2.5 - 1.5 V.

For details, refer to "CAN Communication signal" under CAN Communication System Description CAN Communication System Description.

Reference (50 us time division)

Examples of abnormal waveforms

In case of CAN High signal and/or CAN Low signal wire is shorted to ground circuit

Characteristic waveform
- When CAN High signal wire is shorted to ground circuit: [A]
Both CAN High signal and CAN Low signal are fixed to GND level (0 V) (1).
- When CAN Low signal wire is shorted to ground circuit: [B]
Reference level of both CAN High signal and CAN Low signal is GND level (0 V).
Waveform of CAN High signal oscillates irregularly (4) between 0 V and 3 V and that of CAN Low signal is fixed to 0 V (3).

In case of CAN High signal and/or CAN Low signal wire is open

Characteristic waveform
- When CAN High signal wire is open: [A]
Reference voltage level of CAN High signal and CAN Low signal is unstable and tends to indicate a lower value than in the normal state (2.5 V) (1). Also, waveform of CAN High signal oscillates irregularly (3) but that of CAN Low signal is almost constant (2).
- When CAN Low signal wire is open: [B]
Reference voltage level of CAN High signal and CAN Low signal is unstable and tends to indicate a higher value than in the normal state (2.5 V) (4). Also, waveform of CAN High signal is almost constant (5) but that of CAN Low signal oscillates irregularly (6).

In case of CAN High signal and/or CAN Low signal wire is shorted to power supply (12 V) circuit

Characteristic waveform

Both CAN High signal and CAN Low signal are fixed to 12 V (2).

In case of CAN High signal and/or CAN Low signal wire is shorted to power supply (5 V) circuit

Characteristic waveform
- When CAN High signal wire is shorted to power supply (5 V) circuit: [A]
Reference voltage (1) is 5 V for both CAN High signal and CAN Low signal.
Waveform of CAN High signal oscillates irregularly near 5 V (3) and that of CAN Low signal between 5 V and 2 V (4).
- When CAN Low signal wire is shorted to power supply (5 V) circuit: [B]
Reference voltage (5) is 5 V and of the same phase for both CAN High signal and CAN Low signal and their waveform oscillates irregularly (6) between 5 V and 2.5 V.

In case of CAN High signal and CAN Low signal wire are shorted each other

Characteristic waveform

Both CAN High signal and CAN Low signal are fixed to near 2.5 V (1).

Troubleshooting (Advanced Air Bag Model)

Perform inspection according to the following troubleshooting procedure.

NOTE:

- When performing "Communication Bus Check" using SUZUKI scan tool (SUZUKI-SDT) in each step of this troubleshooting, use the following table to determine whether the control module is in good condition or not.
Also, while performing "Communication Bus Check", do not perform any work other than instructed in this troubleshooting. Or, it may occur that display of control module / sensor on SUZUKI-SDT screen and/or its background color may change.

- Check vehicle specifications and comprehend yourself with installed control modules before inspection. Then, perform troubleshooting procedure.

1. CAN communication line check

Turn ignition switch to OFF position.
Disconnect connectors of all control modules / sensors communicating by means of CAN.
Check for proper terminal connection to each CAN communication circuit at all control module / sensors (communicated by CAN) connectors.
If OK, check each CAN communication circuit for breaking, shorting to power circuit, shorting to ground circuit, shorting to each other CAN communication wire or high resistance, based on results obtained through measurement and identification of trouble nature in Steps 2) and 3) of Diagnosis Procedure.

Are all CAN communication circuits in good condition?
YES -
Go to Step 2.
NO -
Repair CAN communication line.

2. ECM CAN terminating resistance check

Connect connector to ECM.
Measure resistance between "E53-43" and "E53-44" terminal at ESP(R) control module connector.

Is resistance 114 - 134 ohms?
YES -
Go to Step 3.
NO -
Substitute a known-good ECM and recheck.

3. Combination meter CAN terminating resistance check

Connect connector to combination meter.
Measure resistance between "G31-1" and "G31-3" terminal of BCM connector.

Is resistance 114 - 134 ohms?
YES -
Go to Step 4.
NO -
Substitute a known-good combination meter and recheck.

4. ECM, combination meter and BCM check

Turn ignition switch to OFF position.
Connect connector to BCM.
Using service wire (1), connect terminals of ESP(R) control module connector as follows.
- Connect service wire between "E53-43" and "E53-42" terminal of ESP(R) control module connector.
- Connect service wire between "E53-44" and "E53-45" terminal of ESP(R) control module connector.

Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter and BCM.

Is communication normal?
YES -
A/T model: Go to Step 5.
M/T model: Go to Step 6.
NO -
Go to Step 12.

5. TCM check

Turn ignition switch to OFF position.
Connect connector to TCM.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM and TCM.

Is communication normal?
YES -
Go to Step 6.
NO -
Substitute a known-good TCM and recheck.

6. HVAC control module check

Turn ignition switch to OFF position.
Connect connector to HVAC control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model) and HVAC control module.

Is communication normal?
YES -
Keyless start model: Go to Step 7.
Non-keyless start model: Go to Step 8.
NO -
Substitute a known-good HVAC control module and recheck.

7. Keyless start control module check

Turn ignition switch to OFF position.
Connect connector to keyless start control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model), HVAC control module and keyless start control module.

Is communication normal?
YES -
Go to Step 8.
NO -
Substitute a known-good keyless start control module and recheck.

8. Steering angle sensor check

Turn ignition switch to OFF position.
Connect connector to steering angle sensor.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model), HVAC control module, keyless start control module (keyless start model) and steering angle sensor.

Is communication normal?
YES -
Motor-shift type 4WD model: Go to Step 9.
Non-shift type 4WD model or 2WD model: Go to Step 10.
NO -
Replace steering angle sensor.

9. 4WD control module check

Turn ignition switch to OFF position.
Connect connector to 4WD control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model), HVAC control module, keyless start control module (keyless start model), steering angle sensor and 4WD control module.

Is communication normal?
YES -
Go to Step 10.
NO -
Substitute a known-good 4WD control module and recheck.

10. SDM check

Turn ignition switch to OFF position.
Connect connector to SDM.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model), HVAC control module, keyless start control module (keyless start model), steering angle sensor, 4WD control module (motor-shift type 4WD model) and SDM.

Is communication normal?
YES -
With immobilizer model: Go to Step 11.
Without immobilizer model: Substitute a known-good ESP(R) control module and recheck.
NO -
Substitute a known-good SDM and recheck.

11. ESP(R) control module check

Turn ignition switch to OFF position.
Disconnect service wires connected in Step 4 from ESP(R) control module.
Connect connector to ESP(R) control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, TCM (A/T model), HVAC control module, keyless start control module (keyless start model), steering angle sensor, 4WD control module (motor-shift type 4WD model), SDM and ESP(R) control module.

Is communication normal?
YES -
Replace ID controller with new one.
NO -
Substitute a known-good ESP(R) control module and recheck.

12. BCM check

Turn ignition switch to OFF position.
Disconnect connector from BCM.
Using service wire (1), connect terminals of BCM connector as follows.
- Connect service wire between "G31-3" and "G31-4" terminal of BCM connectors.
- Connect service wire between "G31-2" and "G31-1" terminal of BCM connectors.

Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM and combination meter.

Is communication normal?
YES -
Substitute a known-good BCM and recheck.
NO -
Go to Step 13.

13. Combination meter check

Turn ignition switch to OFF position.
Disconnect service wires connected in Step 4 from ESP(R) control module connector.
Disconnect service wires connected in Step 12 from BCM connector.
Turn ignition switch to ON position.
Observe waveform obtained at "G31-1" and "G31-3" terminals of BCM connector.

Is observed waveform normal?
YES -
Substitute a known-good ECM and recheck.
NO -
Substitute a known-good combination meter and recheck.

Troubleshooting (Non-Advanced Air Bag Model)

Perform inspection according to the following troubleshooting procedure.

NOTE:

- When performing "Communication Bus Check" using SUZUKI scan tool (SUZUKI-SDT) in each step of this troubleshooting, use the following table to determine whether the control module is in good condition or not.
Also, while performing "Communication Bus Check", do not perform any work other than instructed in this troubleshooting. Or, it may occur that display of control module / sensor on SUZUKI-SDT screen and/or its background color may change.

- Check vehicle specifications and comprehend yourself with installed control modules before inspection. Then, perform troubleshooting procedure.

1. CAN communication line check

Turn ignition switch to OFF position.
Disconnect connectors of all control modules / sensors communicating by means of CAN.
Check for proper terminal connection to each CAN communication circuit at all control module / sensors (communicated by CAN) connectors.
If OK, check each CAN communication circuit for breaking, shorting to power circuit, shorting to ground circuit, shorting to each other CAN communication wire or high resistance, based on results obtained through measurement and identification of trouble nature in Steps 2) and 3) of Diagnosis Procedure.

Are all CAN communication circuits in good condition?
YES -
Go to Step 2.
NO -
Repair CAN communication line.

2. ECM CAN terminating resistance check

Connect connector to ECM.
Check CAN terminating resistance in ECM as follows.
- ESP(R) model:
Measure resistance between "E53-43" and "E53-44" terminal at ESP(R) control module connector.
- Non-ESP(R) model:
Measure resistance between "E03-10" and "E03-8" terminal at ABS control module connector.

Is resistance 114 - 134 ohms?
YES -
Go to Step 3.
NO -
Substitute a known-good ECM and recheck.

3. Combination meter CAN terminating resistance check

Connect connector to combination meter.
Measure resistance between "G31-1" and "G31-3" terminal of BCM connector.

Is resistance 114 - 134 ohms?
YES -
Go to Step 4.
NO -
Substitute a known-good combination meter and recheck.

4. ECM, combination meter and BCM check

Turn ignition switch to OFF position.
Connect connector to BCM.
Using service wire (1), connect terminals of ABS / ESP(R) control module connector as follows.
- ESP(R) model [A]:
- Connect service wire between "E53-43" and "E53-42" terminal of ESP(R) control module connector.
- Connect service wire between "E53-44" and "E53-45" terminal of ESP(R) control module connector.
- Non-ESP(R) model [B]:
- Connect service wire between "E03-12" and "E03-10" terminal of ABS control module connector.
- Connect service wire between "E03-6" and "E03-8" terminal of ABS control module connector.

Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter and BCM.

Is communication normal?
YES -
4WD model: Go to Step 5.
2WD model: Go to Step 6.
NO -
Go to Step 10.

5. 4WD control module check

Turn ignition switch to OFF position.
Connect connector to 4WD control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM and 4WD control module.

Is communication normal?
YES -
Go to Step 6.
NO -
Substitute a known-good 4WD control module and recheck.

6. TCM check

Turn ignition switch to OFF position.
Connect connector to TCM.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, 4WD control module (motor-shift type 4WD model) and TCM.

Is communication normal?
YES -
Keyless start model: Go to Step 7.
Non-keyless start model: Go to Step 9.
NO -
Substitute a known-good TCM and recheck.

7. Keyless start control module check

Turn ignition switch to OFF position.
Connect connector to keyless start control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, 4WD control module (motor-shift type 4WD model), TCM and keyless start control module.

Is communication normal?
YES -
Go to Step 8.
NO -
Substitute a known-good keyless start control module and recheck.

8. Steering angle sensor check

Turn ignition switch to OFF position.
Connect connector to steering angle sensor.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, 4WD control module (motor-shift type 4WD model), TCM, keyless start control module and steering angle sensor.

Is communication normal?
YES -
Go to Step 9.
NO -
Replace steering angle sensor.

9. HVAC control module check

Turn ignition switch to OFF position.
Connect connector to HVAC control module.
Turn ON ignition switch and select "Communication Bus Check" under "Bus Check" for SUZUKI scan tool.
Check that CAN communication is normal condition for ECM, combination meter, BCM, 4WD control module (motor-shift type 4WD model), TCM, keyless start control module (keyless start model), steering angle sensor (ESP(R) model) and HVAC control module.

Is communication normal?
YES -
Substitute a known-good ABS / ESP(R) control module and recheck.
NO -
Substitute a known-good HVAC control module and recheck.

10. BCM check

Turn ignition switch to OFF position.
Disconnect connector from BCM.
Using service wire (1), connect terminals of BCM connector as follows.
- Connect service wire between "G31-3" and "G31-4" terminal of BCM connectors.
- Connect service wire between "G31-2" and "G31-1" terminal of BCM connectors.