Hummer H3. Manual - part 4

DTC P0563

Circuit Description

The powertrain control module (PCM) continuously monitors that the system voltage stays within
the proper range. If the PCM detects an excessively high system voltage, DTC P0563 will set. A
high voltage condition may cause a stalling condition or other driveability concerns.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0563 System Voltage High

Conditions for Running the DTC

The engine run time is more than 20 seconds.

The engine is running above 1,200 RPM.

Vehicle speed is above 8 km/h (5 mph).

Conditions for Setting the DTC

The PCM senses the system voltage is above 19 volts.

All of the conditions are present for 5 seconds.

Action Taken When the DTC Sets

The PCM stores DTC P0563 in the PCM memory when the diagnostic runs and fails.

The PCM will record the operating conditions at the time the diagnostic fails. The PCM
stores this information in Failure Records.

The PCM disables most outputs.

The transmission defaults to a predetermined gear.

The torque converter clutch (TCC) operation is inhibited.

The instrument panel cluster (IPC) displays a message.

The malfunction indicator lamp (MIL) will not illuminate.

specified in the supporting text, if
applicable.

Does the DTC reset?

Go to Step 2 System OK

2006 Hummer H3

2006 ENGINE Engine Electrical - H3

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present.

A history DTC will clear after 40 malfunction free ignition cycles.

The PCM receives the clear code command from the scan tool.

DTC P0563

Step

Action

Values

Yes

Schematic Reference: Starting and Charging Schematics
Connector End View Reference: Engine Electrical Connector End Views

Did you perform the Diagnostic System
Check - Vehicle?

Go to Step 2

Go to

Diagnostic

System

Check -

Vehicle in

Vehicle DTC

Information

1. Turn OFF all the accessories.

2. Measure the battery voltage at the

battery using the DMM.

3. Operate the engine speed above

2,000 RPM.

Is the battery voltage less than the
specified value?

19 V

Go to Step 4 Go to Step 3

Replace the generator. Refer to Generator
Replacement.
Is the action complete?

Go to Step 5

Replace the powertrain control module
(PCM). Refer to Control Module
References in Computer/Integrating
Systems for replacement, setup, and
programming.
Did you compete the replacement?

Go to Step 5

1. Select the DTC option and the Clear

DTC Information option using the
scan tool.

2. Operate the vehicle within the

2006 Hummer H3

2006 ENGINE Engine Electrical - H3

DTC P0621

Circuit Description

The powertrain control module (PCM) uses the generator turn on signal circuit to control the
load of the generator on the engine. A high side driver in the PCM applies a voltage to the
voltage regulator. This signals the voltage regulator to turn the field circuit ON and OFF. When
the PCM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the
PCM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.

The PCM monitors the state of the generator turn on signal circuit. The PCM should detect a low
generator turn on signal circuit voltage when the key is ON and the engine is OFF, or when the
charging system malfunctions. With the engine running, the PCM should detect a high generator
turn on signal circuit. The PCM performs key ON and RUN tests to determine the status of the
generator turn on signal circuit. During the key ON test, if the PCM detects a high generator turn
on signal circuit voltage, DTC P0621 will set. DTC P0621 will also set if, during the RUN test,
the PCM detects a low generator turn on signal circuit. When the DTC sets, the PCM will send a
class 2 serial data message to the instrument panel cluster (IPC) to illuminate the charge indicator.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0621 Generator L-Terminal Circuit

Conditions for Running the DTC

The ignition is ON.

The engine speed is more than 1,000 RPM.

Conditions for Setting the DTC

The PCM detects the GEN L-Terminal active with the ignition ON.

The PCM detects the GEN L-Terminal inactive with the engine operating.

The above conditions are present for 6 seconds.

Conditions for Running the DTC as
specified in the supporting text, if
applicable.

Does the DTC reset?

Go to Step 2 System OK

2006 Hummer H3

2006 ENGINE Engine Electrical - H3

Action Taken When the DTC Sets

The PCM will record the operating conditions presents when the DTC set as Failure
Records data only.

The IPC displays a message.

The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present.

A history DTC will clear after 40 malfunction free ignition cycles.

The PCM receives the clear code command from the scan tool.

DTC P0621

Step

Action

Yes

Schematic Reference: Starting and Charging Schematics
Connector End View Reference: Engine Electrical Connector End Views

Did you perform the Diagnostic System Check -
Vehicle?

Go to Step 2

Go to

Diagnostic

System Check -

Vehicle in

Vehicle DTC

Information

1. Install a scan tool.

2. Start the engine.

3. With a scan tool, monitor the DTC

information for DTC P0621 in Engine
Controls.

Does the scan tool indicate that DTC P0621 has
passed?

Go to Testing

for

Intermittent

Conditions and

Poor

Connections in

Wiring Systems

Go to Step 3

Test the generator turn on signal circuit for a short
or open. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 6

Go to Step 4

Inspect for poor connections at the harness
connector of the powertrain control module
(PCM). Refer to Connector Repairs in Wiring

2006 Hummer H3

2006 ENGINE Engine Electrical - H3

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