AIR SUSPENSION SYSTEM, Diagnostic DTC:C1751

DTC Code DTC Name
C1751 Compressor Relay Coil Malfunction

DESCRIPTION

The signal from the suspension control ECU turns on the AIR SUS relay, and then the height control compressor motor starts.

DTC No. DTC Detection Condition Trouble Area
C1751

When either of the following is detected:


  • With the AIR SUS relay not activated, an open signal of the AIR SUS relay is detected for 1 second or more.

  • With the AIR SUS relay activated, a short signal of the AIR SUS relay is detected 8 times successively.

  • AIR SUS relay

  • Wire harness or connector

  • Suspension control ECU

WIRING DIAGRAM

A01NGWUE03

INSPECTION PROCEDURE

Note


  • Before performing troubleshooting, inspect the connectors of related circuits.

  • If DTC C1782 (Power Source Voltage Malfunction) is output at the same time, perform troubleshooting for C1782 first Click here.

  • Before replacing the suspension control ECU, perform all of the following again: 1) symptom simulation Click here; 2) DTC inspection Click here; and 3) Intelligent tester inspection (Data List or Active Test) Click here. If no malfunctions are found in other areas, replace the suspension control ECU.

  • If the suspension control ECU is replaced, the vehicle height offset calibration and registration of vehicle identification information must be performed Click here and Click here

PROCEDURE


  1. INSPECT AIR SUS RELAY


    1. Turn the power switch off.

    2. A01NDCGE01

      Remove the AIR SUS relay from the engine room J/B.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      3 - 5 When battery voltage is not applied between terminals 1 and 2 10 kΩ or higher
      When battery voltage is applied between terminals 1 and 2 Below 1 Ω

    NG

    REPLACE AIR SUS RELAY

    OK

  2. CHECK HARNESS AND CONNECTOR (AIR SUS RELAY - ECU AND BODY GROUND)


    1. Disconnect the A54 ECU connector.

    2. Remove the AIR SUS relay from the engine room J/B.

      A01NHCRE03

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      A54-22 (RC) - J/B AIR SUS relay terminal 1 Always Below 1 Ω
      A54-22 (RC) - Body ground Always 10 kΩ or higher
      J/B AIR SUS relay terminal 2- Body ground Always Below 1 Ω
      Text in Illustration
      *1

      Component without relay

      (Engine Room J/B)

      		 *2

      Rear view of wire harness connector

      (to Suspension Control ECU)
      *3 AIR SUS relay - -
      Result
      Condition Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    B

    REPLACE SUSPENSION CONTROL ECU (for RHD) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE SUSPENSION CONTROL ECU (for LHD) Click here