Sensor I have been told. Need to know which one.

IDLE CONTROL SYSTEM (C-2)
IDLE AIR CONTROL (IAC) MOTOR
Disconnect harness connector to motor. Check resistance across IAC coil terminals "A" and "B" (coil "B") and "C" and "D" (coil "A"). See Fig. 5. Resistance should be 40-80 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace IAC motor.
Check resistance between IAC terminals "B" to "C" and "A" to "D". Resistance should be infinite. If resistance is not as specified, replace IAC motor.
NOTE:Additional testing of Idle Air Control (IAC) motor requires an IAC motor actuator and noid light, or a scan tool capable of cycling PCM output devices (General Motors Tech 1).

Fig. 5: IAC Motor Circuit (Typical)
Courtesy of GENERAL MOTORS CORP.