DTC 51 - Switch Signal: Procedures:

To check throttle position sensor or circuit, see DTC 41. To check A/C switch signal, see following illustrations.

DTC 51 SWITCH SIGNAL TROUBLE

Terminals	Trouble	Condition	STD Voltage
A/C-E1	No Voltage	Air conditioning ON	8-14V

Fig 1: DTC 51 - Schematic

Fig 2: DTC 51 - Diagnostic Flowchart