Note. For circuit reference, see the appropriate WIRING DIAGRAMS article. For connector and terminal identification, see CONNECTOR IDENTIFICATION .
Circuit Description
Voltage is applied to engine speed output circuit by PCM. PCM creates VSS output signal by rapidly grounding this circuit through an internal switch called a driver. Driver operates at same rate as low resolution signal input. Other components on this circuit recognize voltage being pulled to ground as an indication of engine speed.
The primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage on control circuit should be low (near zero). When PCM is commanding a component off, voltage of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other that what is expected, fault line will change causing DTC to set.
DTC will set when following conditions are present
- DTCs P0117, P0118 or P1539 not set.
- Engine speed more than 600 RPM.
- PCM detects commanded state of driver and actual state do not match.
- Conditions met for 25.5 seconds.