LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chevrolet >> 2006 >> Uplander Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 5 (Computer/Integrating Systems) >> Diagnostic Information and Procedures >> Power Mode Mismatch >> Test Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 6:  This step tests for battery voltage on the incorrect signal circuits.
  2. 7:  This step tests for no battery voltage on the required signal circuits.
  3. 8:  If any ignition switch parameters that should be inactive in the present ignition switch position are active, 2 ignition switch signal circuits may be shorted together.
  4. 9:  This step eliminates open circuits as the cause of the malfunction.
Power Mode Mismatch

Step Action Yes No
Schematic Reference: Body Control System Schematics 
Connector End View Reference: Computer/Integrating Systems Connector End Views  and Master Electrical Component List in Wiring Systems
IMPORTANT: Open the driver door and leave it open during this test. This will disable the retained accessory power (RAP) mode and eliminate this power mode from the power mode parameter list.
1
  1. Install a scan tool.
  2. Turn OFF the ignition.
  3. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
Does the displayed power mode parameter match the actual ignition switch position?		 Go to Step 2  Go to Step 6 
2
  1. Turn the ignition switch to the UNLOCK position.
  2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
Does the displayed power mode parameter match the actual ignition switch position?		 Go to Step 3  Go to Step 6 
3
  1. Turn the ignition switch to the RUN position, with the engine OFF.
  2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
Does the displayed power mode parameter match the actual ignition switch position?		 Go to Step 4  Go to Step 6 
4
IMPORTANT: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
  1. Turn the ignition switch to the CRANK position.
  2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
Does the displayed power mode parameter match the actual ignition switch position?		 Go to Step 5  Go to Step 6 
5
  1. Turn the ignition switch to the ACCY position.
  2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
Does the displayed power mode parameter match the actual ignition switch position?		 Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 6 
6 
IMPORTANT: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
  1. Turn OFF the ignition.
  2. Disconnect the power mode master (PMM).
  3. Hold the ignition switch in the position that indicated the incorrect power mode.
  4. With a DMM attached to a good ground, test all the PMM ignition switch inputs for positive voltage. Refer to Body Control System Description and Operation  for the state of the input circuits at a specified ignition switch position.
Is voltage present on only the inputs selected by the ignition switch position?		 Go to Step 7  Go to Step 8 
7 
IMPORTANT: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
  1. Hold the ignition switch in the position that indicated the incorrect power mode.
  2. With a DMM attached to a good ground, test the PMM ignition switch inputs for voltage. Refer to Body Control System Description and Operation .
Is voltage not present on only inputs specified for the ignition switch position?		 Go to Step 9  Go to Step 11 
8 
  1. Disconnect the ignition switch.
  2. Test the PMM ignition switch input circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. Test the PMM ignition switch circuits for a short between circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
9 
  1. Disconnect the ignition switch.
  2. Test the PMM ignition switch input circuits for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
10 Inspect for poor connections and terminal tension at the harness connector of the ignition switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 12 
11 Inspect for poor connections and terminal tension at the harness connector of the PMM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 13 
12 Replace the ignition switch. Refer to Ignition Switch Replacement in Steering Wheel and Column.
Did you complete the replacement?		 Go to Step 14  -
13 Replace the PMM. Refer to Control Module References  for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 14  -
14
  1. Reconnect all disconnected components.
  2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
  3. Cycle the ignition switch through all possible positions one at a time.
Does the displayed power mode parameter match the actual ignition switch position?		 System OK Go to Step 1 
scientia non olet · About LEMON Manuals