Switch Condition Signal Circuit - Toyota 3VZ–FE Troubleshooting Manual

EG–412
DTC 51
CIRCUIT DESCRIPTION
Park/Neutral Position Switch Signal*
The ECM uses the signals from the park/neutral position switch to determine whether the transmission is in park
or neutral, or in some other position.
Air Conditioning Switch Signal
The ECM uses the output from the air conditioning switch to determine whether or not the air conditioning is
operating so that it can increase the idling speed of the engine if necessary.
Throttle Position Sensor IDL Signal
The IDL contacts are mounted in the throttle position sensor, and detects the idle condition.
Code No. Diagnostic Trouble Code Detecting Condition
1. 3 sec. or more after engine starts idle switch OFF
(IDL 1)
51 2. *Park/Neutral position switch OFF (PNP).
(Shift position in "R", "D", "2" or "1" position).
3. A/C switch ON.
*: Only vehicles with Electronic Controlled Transmission.
HINT: In this circuit, diagnosis can only be made in the test mode.
WIRING DIAGRAM
ENGINE TROUBLESHOOTING

Switch Condition Signal Circuit

– CIRCUIT INSPECTION
Throttle position sensor IDL circuit.
Accelerator pedal and cable
A/C switch circuit
ECM
Trouble Area