TIRE PRESSURE WARNING SYSTEM TERMINALS OF ECU


  1. CHECK TIRE PRESSURE WARNING ECU AND RECEIVER


    1. A005BDME01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Tire Pressure Warning ECU and Receiver)

      Disconnect the R42 tire pressure warning ECU and receiver connector and measure the voltage or resistance on the wire harness side.

      Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition
      R42-1 (IG) - R42-12 (GND) LG - W-B IG power source Power switch on (IG) 10 to 16 V
      R42-7 (+B) - R42-12 (GND) B - W-B Power supply (from auxiliary battery) Always 10 to 16 V
      R42-12 (GND) - Body ground W-B - Body ground Ground Always Below 1 Ω

    2. Connect the R42 tire pressure warning ECU and receiver connector.

    3. Measure the voltage and resistance according to the value(s) in the table below. If the result is not as specified, the ECU may be malfunctioning.

      Tech Tips

      Inspect the connectors from the back side while the connectors are connected.

      A005ACME01
      Text in Illustration
      *a

      Component with harness connected

      (Tire Pressure Warning ECU and Receiver)

      		 - -
      Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition
      R42-3 (CLSW) - R42-12 (GND) Y - W-B Tire pressure warning reset switch

      • Power switch on (IG)

      • Tire pressure warning reset switch on

      		 Below 1.5 V

      • Power switch on (IG)

      • Tire pressure warning reset switch off

      		 8 to 15 V
      R42-4 (RDA) - R42-12 (GND) GR - W-B Output signals Power switch on (IG) Pulse generation (see waveform 1)
      R42-5 (PRG) - R42-12 (GND) P - W-B Input signals Power switch on (IG) Pulse generation (see waveform 1)
    4. A005A1QE05
      Text in Illustration
      *a Example
      *b GND

      Using an oscilloscope, check waveform 1.

      Waveform 1:
      Item Contents
      Terminal

      R42-4 (RDA) - R42-12 (GND)

      R42-5 (PRG) - R42-12 (GND)
      Tool setting 5 V/DIV, 5 ms./DIV.
      Vehicle condition Power switch on (IG)

      Tech Tips

      The waveform shown in the illustration is an example. If the tester displays a waveform that alternates between high and low, where high is a voltage that is between the IG power source voltage and a voltage 2.2 V lower than the IG power source voltage, and where low is a voltage of between 0 and 1.2 V, the ECU can be judged normal.