LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2021 >> 6 Signature >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> On-Board Diagnostic - Front Body Control Module (FBCM) >> DTC U0338-09: Error Light Switch Signal Received From Start Stop Unit (FBCM) >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

DTC U0338:09 (FBCM) DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FRONT BODY CONTROL MODULE (FBCM) DTCs AGAIN
  • Clear the DTC for the front body control module (FBCM) using the MMDS. (See CLEARING DTC (FBCM) .)
  • Retrieve the front body control module (FBCM) DTCs using the MMDS. (See DTC INSPECTION (FBCM) .)
  • Is the same Pending DTC present?
Yes Go to the next step.
No Go to Step 6.
2 VERIFY START STOP UNIT DTCs Yes Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
(See DTC TABLE [START STOP UNIT] .)
No Go to the next step.
3 INSPECT LIGHT SWITCH Yes Go to the next step.
No Replace the light switch, then go to Step 5.
(See LIGHT SWITCH REMOVAL/INSTALLATION .)
4 PERFORM DTC INSPECTION AND VERIFY START STOP UNIT MALFUNCTION
  • Clear the DTC for the front body control module (FBCM) using the MMDS. (See CLEARING DTC (FBCM) .)
  • Retrieve the front body control module (FBCM) DTCs using the MMDS. (See DTC INSPECTION (FBCM) .)
  • Is the same Pending DTC present?
Yes Replace the start stop unit, then go to the next step.
(See START STOP UNIT REMOVAL/INSTALLATION .)
No Go to Step 6.
5 VERIFY THAT REPAIRS HAVE BEEN COMPLETED
  • Clear the DTC for the front body control module (FBCM) using the MMDS. (See CLEARING DTC (FBCM) .)
  • Retrieve the front body control module (FBCM) DTCs using the MMDS. (See DTC INSPECTION (FBCM) .)
  • Is the same Pending DTC present?
Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
6 VERIFY IF OTHER DTCs DISPLAYED
  • Are any other DTCs displayed?
Yes Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
(See DTC TABLE (FBCM) .)
No DTC troubleshooting completed.