Description

Low ACC power supply voltage input to connectivity master unit (CMU)

Detection condition

• The connectivity master unit (CMU) detects ACC power supply circuit voltage of 8.0 ± 0.8 V or less for 10 s or more with the ignition switched to ACC or ON (engine off or on).

Fail-safe

Not applicable

Possible cause

• DTCs are stored in the PCM.

• Battery malfunction

• Generator malfunction

• Connectivity master unit (CMU) connector or terminal malfunction

• Connectivity master unit (CMU) ACC power supply circuit malfunction

• Short to ground in wiring harness between MIRROR 7.5 A fuse and connectivity master unit (CMU) terminal 2Q

• MIRROR 7.5 A fuse malfunction

• Open circuit in wiring harness between ACC relay terminal C and connectivity master unit (CMU) terminal 2Q

• Connectivity master unit (CMU) malfunction

Step

Inspection

Action

1

• Retrieve the PCM DTCs using the M-MDS.

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• Are any DTCs displayed?

Yes

Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

2

• Inspect the battery.

  (See BATTERY INSPECTION.)

• Is the battery normal?

Yes

Go to the next step.

No

Recharge or replace the battery, then go to Step 6.

(See BATTERY RECHARGING.)

(See BATTERY REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

3

• Inspect the generator.

  (See GENERATOR INSPECTION [SKYACTIV-G 2.0].)

• Is the generator normal?

Yes

Go to the next step.

No

Replace the generator, then go to Step 6.

(See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

4

• Switch the ignition off.

• Disconnect the negative battery cable.

  (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

• Disconnect the connectivity master unit (CMU) connector.

• Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.

• Is the connector normal?

Yes

Go to the next step.

No

Repair or replace the connector, then go to Step 6.

5

• Verify that the connectivity master unit (CMU) connector is disconnected.

• Connect the negative battery cable.

  (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

• Measure the voltage at connectivity master unit (CMU) terminal 2Q (wiring harness-side).

• Is the voltage B+?

Yes

Go to the next step.

No

Inspect the MIRROR 7.5 A fuse.

• If the fuse is blown:

• Refer to the wiring diagram and verify if there is a common connector between MIRROR 7.5 A fuse and connectivity master unit (CMU) terminal 2Q.

If there is a common connector:

• Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.

• Repair or replace the malfunctioning part.

If there is no common connector:

• Repair or replace the wiring harness which has a short to ground.

• Replace the fuse.

• If the fuse is damaged:

• Replace the fuse.

• If the fuse is normal:

• Refer to the wiring diagram and verify if there is a common connector between ACC relay terminal C and connectivity master unit (CMU) terminal 2Q.

If there is a common connector:

• Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.

• Repair or replace the malfunctioning part.

If there is no common connector:

• Repair or replace the wiring harness which has an open circuit.

Go to the next step.

6

• Always reconnect all disconnected connectors.

• Connect the negative battery cable.

  (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

• Clear the DTC for the connectivity master unit (CMU) using the M-MDS.

  (See CLEARING DTC [CONNECTIVITY MASTER UNIT].)

• Switch the ignition ON (engine off or on) and wait for 17 s or more.

• Retrieve the connectivity master unit (CMU) DTCs using the M-MDS.

  (See DTC INSPECTION [CONNECTIVITY MASTER UNIT].)

• Is the same DTC displayed?

Yes

Repeat the inspection from Step 1.

• If the malfunction recurs, replace the connectivity master unit (CMU).

  (See CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION.)

Go to the next step.

No

Go to the next step.

7

• Are any other DTCs displayed?

Yes

Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.

(See DTC TABLE [CONNECTIVITY MASTER UNIT].)

No

DTC troubleshooting completed.