DTC U0420:00 [VEHICLE CONTROL MODULE (V/C-MODULE)]

id0102i0005500

System malfunction location

Error signal received from EPS control module

Detection condition

•  Communication error between EPS control module and vehicle control module (V/C-module)

Fail-safe

•  Inhibits the mazda radar cruise control (MRCC) system control

•  Inhibits the smart brake support (SBS) system control

•  Inhibits the distance recognition support system (DRSS) control

Possible cause

•  EPS control module malfunction

•  Vehicle control module (V/C-module) malfunction

System wiring diagram

•  Not applicable

System malfunction location	Error signal received from EPS control module
Detection condition	• Communication error between EPS control module and vehicle control module (V/C-module)
Fail-safe	• Inhibits the mazda radar cruise control (MRCC) system control • Inhibits the smart brake support (SBS) system control • Inhibits the distance recognition support system (DRSS) control
Possible cause	• EPS control module malfunction • Vehicle control module (V/C-module) malfunction
System wiring diagram	• Not applicable

Diagnostic Procedure

Step

Inspection

Action

1

PERFORM DTC INSPECTION FOR EPS CONTROL MODULE

•  Perform the EPS control module DTC inspection using the M-MDS.
(See ELECTRIC POWER STEERING (EPS) ON-BOARD DIAGNOSIS.)

•  Are any DTCs present?

Yes

Go to the applicable DTC inspection.

(See ELECTRIC POWER STEERING (EPS) ON-BOARD DIAGNOSIS.)

Then go to Step 3.

No

Go to the next step.

2

PERFORM DTC INSPECTION FOR VEHICLE CONTROL MODULE (V/C-MODULE)

•  Clear vehicle control module (V/C-module) DTCs using the M-MDS.
(See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].)

•  Switch the ignition ON (engine on).

•  Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS.
(See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].)

•  Is the same DTC present?

Yes

Replace the EPS control module, then go to the next step.

(See STEERING WHEEL AND COLUMN REMOVAL/INSTALLATION.)

No

Go to the next step.

3

VERIFY THAT REPAIRS HAVE BEEN COMPLETED

•  Clear vehicle control module (V/C-module) DTCs using the M-MDS.
(See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].)

•  Switch the ignition ON (engine on).

•  Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS.
(See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].)

•  Is the same DTC present?

Yes

Repeat the inspection from Step 1.

•  If the malfunction recurs, replace the vehicle control module (V/C-module).
(See VEHICLE CONTROL MODULE (V/C-MODULE) REMOVAL/INSTALLATION [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM].)

Go to the next step.

No

Go to the next step.

4

VERIFY THAT NO OTHER DTCs ARE PRESENT

•  Verify other DTCs displayed.

•  Are any other DTCs output?

Yes

Perform the corresponding DTC inspection.

No

DTC troubleshooting completed.

Step	Inspection		Action
1	PERFORM DTC INSPECTION FOR EPS CONTROL MODULE • Perform the EPS control module DTC inspection using the M-MDS. (See ELECTRIC POWER STEERING (EPS) ON-BOARD DIAGNOSIS.) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See ELECTRIC POWER STEERING (EPS) ON-BOARD DIAGNOSIS.) Then go to Step 3.
1		No	Go to the next step.
2	PERFORM DTC INSPECTION FOR VEHICLE CONTROL MODULE (V/C-MODULE) • Clear vehicle control module (V/C-module) DTCs using the M-MDS. (See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].) • Switch the ignition ON (engine on). • Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS. (See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].) • Is the same DTC present?	Yes	Replace the EPS control module, then go to the next step. (See STEERING WHEEL AND COLUMN REMOVAL/INSTALLATION.)
2		No	Go to the next step.
3	VERIFY THAT REPAIRS HAVE BEEN COMPLETED • Clear vehicle control module (V/C-module) DTCs using the M-MDS. (See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].) • Switch the ignition ON (engine on). • Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS. (See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].) • Is the same DTC present?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the vehicle control module (V/C-module). (See VEHICLE CONTROL MODULE (V/C-MODULE) REMOVAL/INSTALLATION [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM].) Go to the next step.
3		No	Go to the next step.
4	VERIFY THAT NO OTHER DTCs ARE PRESENT • Verify other DTCs displayed. • Are any other DTCs output?	Yes	Perform the corresponding DTC inspection.
4		No	DTC troubleshooting completed.