TIRE PRESSURE WARNING SYSTEM TERMINALS OF ECU

CHECK TIRE PRESSURE WARNING ECU AND RECEIVER

1. 

   *A	for FMVSS138 Type
   *B	for ECE-R64 Type
   *a	Front view of wire harness connector (to Tire Pressure Warning ECU and Receiver)

   Disconnect the Q38 or Q36 tire pressure warning ECU and receiver connector and measure the voltage or resistance on the wire harness side.

   for FMVSS138 Type

   Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
   Q38-1 (IG) - Q38-12 (GND)	B - BR	IG power source	Power switch on (IG)	10 to 16 V
   Q38-7 (+B) - Q38-12 (GND)	G - BR	Power supply (from battery)	Always	10 to 16 V
   Q38-12 (GND) - Body ground	BR - Body ground	Ground	Always	Below 1 Ω

   for ECE-R64 Type

   Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
   Q36-1 (IG) - Q36-12 (GND)	Y - BR	IG power source	Power switch on (IG)	10 to 16 V
   Q36-12 (GND) - Body ground	BR - Body ground	Ground	Always	Below 1 Ω

2. Connect the Q38 or Q36 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

   Measure the values on the wire harness side while the connector is connected.

   

   *A	for FMVSS138 Type	*B	for ECE-R64 Type
   *a	Component with harness connected (Tire Pressure Warning ECU and Receiver)	-	-

   for FMVSS138 Type

   Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
   Q38-3 (CLSW) - Q38-12 (GND)	W - BR	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
   Q38-4 (RDA) - Q38-12 (GND)	B - BR	Output signals	Power switch on (IG)	Pulse generation (see waveform 1)
   Q38-5 (PRG) - Q38-12 (GND)	L - BR	Input signals	Power switch on (IG)	Pulse generation (see waveform 1)

   for ECE-R64 Type

   Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
   Q36-3 (CLSW) - Q36-12 (GND)	W - BR	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
   Q36-4 (RDA2) - Q36-12 (GND)	B - BR	Output signals	Power switch on (IG)	Pulse generation (see waveform 1)
   Q36-5 (PRG2) - Q36-12 (GND)	L - BR	Input signals	Power switch on (IG)	Pulse generation (see waveform 1)

4. 

   *a	Example
   *b	GND

   Using an oscilloscope, check waveform 1.

   Waveform 1:

   Item	Contents
   Terminal	Q38-4 (RDA) - Q38-12 (GND)*1 Q38-5 (PRG) - Q38-12 (GND)*1 Q36-4 (RDA2) - Q36-12 (GND)*2 Q36-5 (PRG2) - Q36-12 (GND)*2
   Tool setting	5 V/DIV, 5 ms./DIV.
   Vehicle condition	Power switch on (IG)

   
   

   • *1: for FMVSS138 Type

   • *2: for ECE-R64 Type

   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.