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Diagnostic Trouble Code: B0158
Diagnostic Trouble Code Name: Outside Air Temperature Sensor Circuit
Vehicle Make: Pontiac
Vehicle Model: G8 (VE)
Diagnostic Code Entered By: ZerOne
Diagnostic Code Entered On: Wed Oct 06, 2010 11:00 pm
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Please Note: The DTC Information provided has been randomly generated.
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Diagnostic Trouble Code Description:
Cooling Fan Relay 2 Control Circuit High Voltage
Possible Sensor Faults
ECM
Possible Related Diagnostic Trouble Codes
DTC P0480, P0481, P0691, P0692, P0693, or P0694
Circuit / System Description
The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
In low speed operation, the ECM applies ground to the coil side of the cooling fan low speed relay. This energizes the coil and applies voltage directly to the right cooling fan through the switch side of the low speed relay. The right cooling fan is connected in series to the left cooling fan through the de-energized series/parallel (S/P) cooling fan speed control relay. The series circuit operates both fans at low speed.
In high speed operation, the ECM applies a ground to the coil side of the cooling fan low speed relay, the S/P cooling fan speed control relay, and the cooling fan high speed relay. When energized, the high speed fan relay applies voltage directly to the left cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P speed control relay provide ignition voltage and a direct path to ground for the right cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.
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