DTC

U0402:00

Abnormal message from transmission/transaxle

DETECTION CONDITION

• The DSC HU/CM received error signals from the transmission/transaxle for 1 s or more with the ignition switched ON (engine off or on).

FAIL-SAFE FUNCTION

• Illuminates the TCS/DSC indicator light and master warning light*¹.

• Inhibits the TCS, Hill Launch Assist (HLA), vehicle roll prevention function*², DSC, Mazda Radar Cruise Control (MRCC)*², and Smart City Brake Support (SCBS)*² controls.

*¹: Vehicles with Smart City Brake Support (SCBS).

*²: If equipped.

POSSIBLE CAUSE

• The transmission/transaxle could not send a normal signal temporarily (DTCs are stored in the TCM)

• transmission/transaxle malfunction

• DSC HU/CM malfunction

SYSTEM WIRING DIAGRAM

Not applicable

STEP

INSPECTION

ACTION

1

• Switch the ignition off.

• Verify DTCs for the TCM using the M-MDS.

  (See ON-BOARD DIAGNOSTIC SYSTEM DTC INSPECTION [FW6A-EL].)

• Is the DTC displayed?

Yes

Repair the malfunctioning part according to the applicable DTC troubleshooting.

(See ON-BOARD DIAGNOSTIC SYSTEM DTC TABLE [FW6A-EL].)

No

Go to the next step.

2

• Clear DTC for the DSC HU/CM using the M-MDS.

  (See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)].)

• Are the same DTCs present?

Yes

Repeat the inspection from Step 1.

If the malfunction recurs, replace the TCM, then go to the next step.

(See CONTROL VALVE BODY REMOVAL/INSTALLATION [FW6A-EL].)

No

Go to the next step.

3

• Are any other DTCs displayed?

Yes

Repair the malfunctioning part according to the applicable DTC troubleshooting.

(See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)].)

No

DTC troubleshooting completed.