TIRE PRESSURE WARNING SYSTEM TERMINALS OF ECU

CHECK TIRE PRESSURE WARNING ECU AND RECEIVER

1. Measure the voltage and resistance according to the value(s) in the table below. If the result is not as specified, the ECU may have a malfunction.

   Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
   H28-1 (IG) - H28-12 (GND)	W - B	IG power source	Ignition switch ON	11 to 14 V
   H28-4 (BRDA) - H28-12 (GND)	R - B	Output signals	Ignition switch ON	Pulse generation (see waveform 1)
   H28-5 (BPRG) - H28-12 (GND)	P - B	Input signals	Ignition switch ON	Pulse generation (see waveform 1)
   H28-7 (+B) - H28-12 (GND)	Y-R - B	Power Supply	Always	11 to 14 V
   H28-12 (GND) - Body ground	B - Body ground	Ground	Always	Below 1 Ω

2. 

   Text in Illustration

   *a	Example
   *b	GND

   Using an oscilloscope, check waveform 1.

   Waveform 1:

   Item	Contents
   Terminal	H28-4 (BRDA) - H28-12 (GND) H28-5 (BPRG) - H28-12 (GND)
   Tool setting	5 V/DIV, 50 μs./DIV.
   Vehicle condition	Ignition switch ON

   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.