Power Outlets: Diagnosis Chevrolet Silverado Classic 1500

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Hybrid Control Module (HCM)

Energy Storage Control Module (ESCM)

Starter/Generator Control Module (SGCM)

Scan Tool Data List (W/HP2)

Hybrid Control Module (HCM)

Energy Storage Control Module (ESCM)

Starter/Generator Control Module (SGCM)

Scan Tool Data List (W/O HP2)

Powertrain Control Module (PCM)

PCM - Diesel Engines

Circuit Description

The auxiliary power outlet (APO) switch controls the operation of the hybrid control module (HCM) APO state manager. The APO state manager commands one of 3 states from the starter generator control module (SGCM) (APO Off, APO Normal, APO Continuous). The APO switch is a momentary button, its output signal an input to an HCM analogue channel. Five volts are supplied to the switch and the returned voltage is measured relative to HCM signal ground to determine the switch state. A resistor network in the switch circuitry ensures that shorted high and low states can be diagnosed successfully. There are 2 valid voltage ranges of the return signal, one representing switch open, the other representing switch closed. If the voltage is lower than a threshold, a short low is indicated. Similarly, if the voltage is greater than the short high threshold, a short high is indicated.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC B3654 Electrical Power Take Off Control Switch Circuit
2. DTC B3655 Electrical Power Take Off Control Switch Circuit Low
3. DTC B3656 Electrical Power Take Off Control Switch Circuit High

Conditions for Running the DTC

1. The ignition is ON.
2. The APO switch is requested ON.

Conditions for Setting the DTC

1. If voltage is lower than a calibrated value, a short low is indicated.
2. If the voltage is greater than a calibrated value the short high is indicated.
3. This DTC is run every 100 ms.

Action Taken When the DTC Sets

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

Conditions for Clearing the DTC

1. The Conditions for Setting the DTC are no longer present.
2. A history DTC will clear after 40 malfunction-free ignition cycles.
3. The HCM receives the clear code command from the scan tool.

DTC B3654, B3655 or B3656

The starter generator control module (SGCM) uses the interlock circuit to monitor the plugs and connectors for hybrid system function. The interlock indicates the state of the connectors in the 120 voltage circuits. In the SGCM, the primary side of the transformer is connected to a low frequency oscillator circuit. When the loop is complete, the shorted secondary reduces the oscillator voltage, and a comparator senses this as a good and complete interlock loop. If the loop is open, the oscillator amplitude increases and the comparator senses this as a problem.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0A0A High Voltage System Interlock Circuit

The ignition is ON.

1. All conditions met for the vehicle to enter normal or continuous modes.
2. The SGCM run time greater than 5 seconds.

1. The SGCM will record the operating conditions presents when the DTC set as Failure Records data only.
2. The malfunction indicator lamp (MIL) will not illuminate.

1. The Conditions for Setting the DTC are no longer present.
2. A history DTC will clear after 40 malfunction free ignition cycles.
3. The SGCM receives the clear code command from the scan tool.

Diagnostic Aids

Ensure that all connectors are connected properly.

DTC P0A0A

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-277883-S07139257572008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-277883-S33769936482008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-277883-S17347055992008012100000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Testing

1. With the ignition OFF, Isolate the APO circuit that is inoperative by disconnecting the 120-volt harness (orange) from the energy storage box (ESB) and the SGCM.
2. With a DMM, independently test the APO phase A (hot) and the APO neutral circuits for an open. Also, test the same circuits for a short between each other. Refer to «Cigar Lighter/Power Outlet Schematics»(ref-277866-S05459571472008012100000) .
3. Test the APO ground circuits for any shorts. As the circuits are normally open.

1. If a defective circuit is found, repair as necessary.
2. If no trouble found with the APO circuits, replace the appropriate APO receptacles.