July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Probable Causes:

A/C Switch or Switch Circuit
Accelerator Pedal or Cable
Neutral/Start Switch or Switch Circuit
Throttle Position Sensor IDL Circuit
ECU

NOTE: To check A/C switch signal, use the following procedure.

CODE 51/TEST NO. 9-SWITCH SIGNAL TROUBLE

Terminal	Trouble	Condition	STD Voltage
A/C-E1	No Voltage	Air Conditioning ON	8-14V

Fig 1: Code 51/Test No. 9 Schematic Switch Signal

G91G17695

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Code 51/Test No. 9 Flow Chart Switch Signal

G91H17696

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002