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Home >> Acura >> 2025 >> MDX Base >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Body Electrical System - System Description - DTC Troubleshooting Index >> Tests >> Keyless Access System Check
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Keyless Access System Check

1. Connect the HDS to the DLC

2. Turn the vehicle to the ON mode.

3. On the HDS screen, at SYSTEM SELECTION MENU, enter ONE-PUSH START, then select KEYLESS ACCESS CONTROL UNIT or BACKUP CONTROL UNIT.

NOTE:

If the HDS does not communicate, check the body control module power, ground, K-line, and L-line connectors.

4. At KEYLESS ACCESS CONTROL UNIT, enter KEYLESS ACCESS SYSTEM INFORMATION, then select SYSTEM CHECK 1 or SYSTEM CHECK 2.

5. At BACKUP CONTROL UNIT, enter SYSTEM INFORMATION, then select SYSTEM CHECK. If the HDS displays NORMAL N-1, the immobilizer system is OK at this time, refer to the STATUS LOG. If the HDS displays any other messages, check as follows:

System Check 1 (Keyless Access Control Unit) 

System Check No. Possible cause Check items
A-1A-2A-3G-4
  • Keyless remote is mismatched
  • No communication between body control module and keyless remote
  • Keyless remote is not registered
  • Register the keyless remote
  • LF antenna test
  • Check antenna level with the HDS
B-1B-2G-1
  • PCM is not registered
  • No communication between body control module and PCM
  • Body control module is replaced
  • Register the PCM
  • Check PCM
  • Check for an open in the S-NET lines
  • Register the body control module
C-1C-2G-2G-3
  • Body control module is not registered
  • Body control module is replaced
  • Register the body control module
  • Check body control module
  • Check for an open in the S-NET lines
C-3C-4G-5
  • Body control module is replaced
  • Register the body control module
  • Check for an open or short in the IGN_TRX line

System Check 2 (Keyless Access Control Unit) 

System Check No. Possible cause Check items
D-1D-2D-3
  • S-NET line is open or short
  • No communication between body control module and PCM
  • Check for an open or short in the S-NET lines
  • Check body control module
  • Check PCM
D-4D-5 IGN_TRX line is open or short Check for an open or short in the IGN_TRX line

System Check (Backup Control Unit) 

System Check No. Possible cause Check items
A-1A-2A-3
  • Keyless remote is mismatched
  • Engine start/stop switch failure
  • Keyless remote is not registered
  • Register the keyless remote
  • Check engine start/stop switch
B-1B-2
  • PCM is replaced
  • Communication error between body control module and PCM
  • Register the PCM
  • Check PCM
System Check No. Possible cause Check items
C-1C-2 Body control module is replaced
  • Register the body control module
  • Check body control module
  • Check for an open in the S-NET lines
D-1D-2D-3
  • S-NET line is open or short
  • No communication between body control module and PCM
  • Check for an open or short in the S-NET lines
  • Check body control module
  • Check PCM
E-1E-2E-3E-4E-5
  • Body control module is not registered
  • PCM is not registered
  • Keyless remote is not registered
  • Register the body control module
  • Register the keyless remote
  • Register the PCM
F-1F-2F-3F-4F-5F-6 Special Mode Turn the vehicle to the ON mode and then select the OFF (LOCK) mode with a registered keyless remote