2018 Acura MDX BaseFACTORY OEM SERVICE PROCEDURE

Keyless Access System Check (2014 2015)

1. Connect the HDS to the data link connector (DLC) - Refer to: How to Troubleshoot the Body Electrical (2014 2015)

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 keyless access/TPMS control unit 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.

6. 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/TPMS Control Unit)Β 

System Check No. Possible cause Check items
A-1A-2A-3G-4
  • Keyless remote is mismatched
  • 2-way transceiver failure
  • LF interior antenna failure
  • Keyless remote is not registered
  • Keyless remote test
  • 2-way transceiver test
  • LF interior antenna test
  • Register the keyless remote
B-1B-2G-1
  • PCM is replaced
  • No communication between Keyless Access/TPMS Control Unit and PCM
  • Open in the IG1 line
  • Keyless Access/TPMS Control Unit is replaced
  • Register the PCM
  • Check PCM
  • Check harness
  • Register the Keyless Access/TPMS Control Unit
C-1C-2G-2G-3
  • MICU (Imoes unit) is replaced
  • Communication error between Keyless Access/TPMS Control Unit and MICU
  • Open in the IG1 SAFETY line
  • Keyless Access/TPMS Control Unit is replaced
  • Register the Keyless Access/TPMS Control Unit
  • Check MICU
  • Check harness
C-3C-4
  • Electric Steering Lock is replaced
  • Keyless Access/TPMS Control Unit is replaced
  • Register the Keyless Access/TPMS Control Unit
  • Register the Electric Steering Lock
  • Check for an open or short in the wire IGN TRX lines
G-5
  • Electric Steering Lock is replaced
  • Keyless Access/TPMS Control Unit is replaced
  • Register the Keyless Access/TPMS Control Unit
  • Register the Electric Steering Lock
  • Check for an open or short in the wire IGN TRX lines

System Check 2 (Keyless Access/TPMS Control Unit)Β 

System Check No. Possible cause Check items
D-1D-2D-3
  • S-NET line is short
  • No communication between Keyless Access/TPMS Control Unit and MICU (Imoes unit)
  • No communication between Keyless Access/TPMS Control Unit and PCM
  • Check harness
  • Check MICU
  • Check PCM
D-4D-5 IGN TRX line trouble Check IGN TRX line

System Check (Backup Control Unit)Β 

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 Keyless Access/TPMS Control Unit and PCM
  • Register the PCM
  • Check PCM
C-1C-2
  • MICU is replaced
  • Communication error between Keyless Access/TPMS Control Unit and MICU (Imoes unit)
  • Open in the IG1 line
  • Register the Keyless Access/TPMS Control Unit
  • Check MICU
  • Check harness
D-1D-2D-3
  • S-NET line is short
  • No communication between Keyless Access/TPMS Control Unit and MICU (Imoes unit)
  • No communication between Keyless Access/TPMS Control Unit and PCM
  • Check harness
  • Check MICU
  • Check PCM
E-1E-2E-3E-4E-5 Keyless Access/TPMS Control Unit is not registered Register the Keyless Access/TPMS Control Unit
F-1F-2F-3F-4F-5 Special Mode Turn the vehicle to the ON mode and then select the OFF (LOCK) mode with a registered keyless remote
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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