TERMINALS OF ECU CHECK TIRE PRESSURE WARNING ECU AND RECEIVER
(a)
Disconnect the P21 tire pressure warning ECU and receiver connector and
measure the voltage or resistance on the wire harness side.
|
*a | Front view of wire harness connector
(to Tire Pressure Warning ECU and Receiver) | |
Terminal No. (Symbol) | Wiring Color |
Terminal Description | Condition |
Specified Condition | |
P21-1 (IG) - P21-12 (GND) |
R - W-B | IG power source |
Ignition switch ON | 10 to 16 V | |
P21-7 (+B) - P21-12 (GND) |
LG - W-B | Power supply (from battery) |
Always | 10 to 16 V | |
P21-9 (CANH) - P21-10 (CANL) |
SB - P | CAN communication line |
Ignition switch OFF | 54 to 69 Ω | |
P21-12 (GND) - Body ground |
W-B - Body ground | Ground |
Always | Below 1 Ω |
(b) Connect the P21 tire pressure warning ECU and receiver connector. (c)
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. HINT: Measure the values on the wire harness side while the connector is connected.
|
*a | Component with harness connected
(Tire Pressure Warning ECU and Receiver) |
- | - | |
Terminal No. (Symbol) | Wiring Color |
Terminal Description | Condition |
Specified Condition | |
P21-3 (CLSW) - P21-12 (GND) |
W - W-B | Tire pressure warning reset switch |
- Ignition switch ON
- Tire pressure warning reset switch on
| Below 1.5 V |
- Ignition switch ON
- Tire pressure warning reset switch off
| 8 to 15 V | |
P21-4 (RDA) - P21-12 (GND) |
GR - W-B | Output signals |
Ignition switch ON | Pulse generation (see waveform 1) | |
P21-5 (PRG) - P21-12 (GND) |
L - W-B | Input signals |
Ignition switch ON | Pulse generation (see waveform 1) |
(d) Using an oscilloscope, check waveform 1.
Waveform 1: |
Item | Contents | |
Terminal | P21-4 (RDA) - P21-12 (GND)
P21-5 (PRG) - P21-12 (GND) | |
Tool setting | 5 V/DIV, 5 ms./DIV. | |
Vehicle condition | Ignition switch ON |
HINT: 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. | 
