S10/T10 P/U 2WD V6-262 4.3L VIN W CPI (1992)
Manual Transmission Shift Light Circuit
Circuit Description:
The ECM uses information from the following inputs to control the shift light:
^
Coolant Temperature Sensor (CTS)
^
Throttle Position Sensor (TPS)
^
Vehicle Speed Sensor (VSS)
^
RPM
The ECM uses the measured rpm and the vehicle speed to calculate what gear the vehicle is in. It's this calculation that determines when the shift
light should be turned "ON".
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
1. This should not turn "ON" the shift light. If the light is "ON", there is a short to ground in CKT 456 wiring, or a fault in the ECM.
2. This should turn "ON" the shift light
3. This checks for an open in the shift light circuit, or a faulty ECM.
