Engine Control - SFI System

2AZ-FE ENGINE CONTROL: SFI SYSTEM: P0500: Vehicle Speed Sensor "A"

DTC P0500 - Vehicle Speed Sensor "A"

DESCRIPTION

The speed sensors detect the wheel speed and send the appropriate signals to the skid control ECU. The skid control ECU converts these wheel speed signals into a 4-pulse signal and outputs it to the ECM via the combination meter. The ECM determines the vehicle speed based on the frequency of these pulse signals.









MONITOR DESCRIPTION

Automatic Transaxle Models:
The ECM assumes that the vehicle is being driven when the vehicle speed sensor signal is being transmitted by the combination meter. If there is no signal from the combination meter, despite the ECM detecting the speed signal from the speed sensor NC, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and sets the DTC.
Manual Transaxle Models:
The ECM assumes that the vehicle is being driven when the indicated engine speed is more than 2,000 rpm and the engine load calculated by the ECM is more than a certain level or the idle fuel-cut operation* is being executed. If there is no signal from the vehicle speed sensor, despite these conditions being met, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and sets the DTC.
*: Idle fuel-cut is executed when the throttle valve is fully closed and engine speed is over 2800 rpm.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

M/T Models, Case 1





M/T Models, Case 2





A/T Models





TYPICAL MALFUNCTION THRESHOLDS





WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE

1. READ VALUE USING TECHSTREAM (VEHICLE SPEED)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Vehicle Speed.
(e) Drive the vehicle.
(f) Read the value displayed on the Techstream.
OK:
Vehicle speeds displayed on the tester and speedometer display are equal.
NG -- CHECK HARNESS AND CONNECTOR (ECM - COMBINATION METER)
OK -- CHECK FOR INTERMITTENT PROBLEMS
2. CHECK HARNESS AND CONNECTOR (ECM - COMBINATION METER)




(a) Disconnect the ECM connector.
(b) Disconnect the combination meter connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):





(d) Reconnect the ECM connector.
(e) Reconnect the combination meter connector.
NG -- CHECK HARNESS AND CONNECTOR (ECM - INSTRUMENT PANEL JUNCTION BLOCK)
OK -- Continue to next step.
3. CHECK COMBINATION METER ASSEMBLY (SPD SIGNAL WAVEFORM)




(a) Check the output waveform.
(1) Remove the combination meter assembly with the connector(s) still connected.
(2) Connect an oscilloscope to terminals E46-36 (+S) and body ground.
(3) Turn the ignition switch to ON.
(4) Turn the wheel slowly.
(5) Check the signal waveform according to the condition(s) in the table below.






OK:
The waveform is displayed as shown in the illustration.
HINT: When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

NG -- GO TO METER / GAUGE SYSTEM
OK -- REPLACE ECM
4. CHECK HARNESS AND CONNECTOR (ECM - INSTRUMENT PANEL JUNCTION BLOCK)
(a) Disconnect the ECM connector.




(b) Disconnect the instrument panel junction block connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):





(d) Reconnect the ECM connector.
(e) Reconnect the instrument panel junction block connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - INSTRUMENT PANEL JUNCTION BLOCK)
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK)