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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 939 (CRUISE CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESCRUISE CONTROL INOPERATIVE/MALFUNCTIONING (WITH THROTTLE ACTUATOR CONTROL)TEST DESCRIPTION
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Test Description

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Test Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2007 GMC Savana Special, 2007 GMC Savana Camper Special, 2007 GMC Savana, 2007 Chevrolet RV Cutaway, and 2007 Chevrolet Cutaway. 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. 8:  This step tests the center high mounted stop lamp (CHMSL) supply voltage/stop lamp supply voltage circuit for an open or for a high resistance between the stop lamp switch and the throttle actuator control (TAC) module.
  2. 9:  This step tests the cruise control set/coast switch signal circuit for an open or for a high resistance.
  3. 10:  This step tests the cruise control resume/accel switch signal circuit for an open or for a high resistance.
  4. 11:  This step tests the ignition 3 voltage circuit for an open, for a short to ground, or for a high resistance.
  5. 29:  The DTCs will set in the powertrain control module (PCM) when you perform this table.
Cruise Control Inoperative/Malfunctioning (With Throttle Actuator Control)

Step Action Yes No
Schematic Reference : Cruise Control Schematics 
Connector End View Reference: Cruise Control Connector End Views  or Powertrain Control Module Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Turn the cruise control On/Off switch OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter in the powertrain control module (PCM) Cruise Control Data data list.
Does the Cruise On/Off Switch parameter display Off?		 Go to Step 4  Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect C4 of the multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter.
Does the Cruise On/Off Switch parameter display Off?		 Go to Step 22  Go to Step 13 
4
  1. Turn the cruise control On/Off switch ON.
  2. With the scan tool, observe the Cruise On/Off Switch parameter.
Does the Cruise On/Off Switch parameter display On?		 Go to Step 5  Go to Step 11 
5
  1. With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM Cruise Control Data data list.
  2. Turn the cruise control On/Off switch ON.
  3. Press and hold the cruise control Set/Coast button.
Does the Cruise Set/Coast Switch parameter Display On?		 Go to Step 6  Go to Step 9 
6
  1. With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM Cruise Control Data data list.
  2. Press and hold the Resume/Accel switch.
Does the Cruise Resume/Accel. Switch parameter Display On?		 Go to Step 7  Go to Step 10 
7 Do the stop lamps operate properly? Go to Step 8  Go to Stop Lamps Inoperative
8 
  1. With the scan tool, observe the Stoplamp Pedal Switch parameter in the PCM Cruise Control Data data list.
  2. Depress and hold the brake pedal.
Does the Stoplamp Pedal Switch parameter Display Applied?		 Go to Diagnostic Aids Go to Step 21 
9 
  1. Turn OFF the ignition.
  2. Disconnect C4 of the multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a 3-amp fused jumper between the cruise control set/coast switch signal circuit and the ignition 3 voltage circuit.
  5. With the scan tool, observe the Cruise Set/Coast Switch parameter.
Does the Cruise Set/Coast Switch parameter Display On?		 Go to Step 22  Go to Step 19 
10 
  1. Turn OFF the ignition.
  2. Disconnect C4 of the multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a 3-amp fused jumper between the cruise control resume/accel switch signal circuit and the ignition 3 voltage circuit.
  5. With the scan tool, observe the Cruise Resume/Accel. Switch parameter.
Does the Cruise Resume/Accel. Switch parameter Display On?		 Go to Step 22  Go to Step 20 
11 
  1. Turn OFF the ignition.
  2. Disconnect C4 of the multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition 3 voltage circuit and a good ground.
Does the test lamp illuminate?		 Go to Step 12  Go to Step 15 
12
  1. Connect a 3-amp fused jumper between the ignition 3 voltage circuit and the cruise control on switch signal circuit.
  2. With the scan tool, observe the Cruise On/Off Switch parameter.
Does the Cruise On/Off Switch parameter display On?		 Go to Step 22  Go to Step 18 
13 Test the cruise control on switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 14 
14
  1. Turn OFF the ignition.
  2. Disconnect C1 of the throttle actuator control (TAC) module.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter.
Does the Cruise On/Off Switch parameter display On?		 Go to Step 24  Go to Step 23 
15 Test the cruise control set/coast switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 16 
16 Test the cruise control resume/accel switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 17 
17 Test the cruise control on switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 25 
18 Test the cruise control on switch signal circuit for the following:
  • An open
  • A high resistance
  • A short to ground

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 23 
19 Test the cruise control set/coast switch signal circuit for the following:
  • An open
  • A high resistance
  • A short to ground

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 23 
20 Test the cruise control resume/accel switch signal circuit for the following:
  • An open
  • A high resistance
  • A short to ground

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 23 
21 Test the center high mounted stop lamp (CHMSL) supply voltage/stop lamp supply voltage circuit for an open or a high resistance between the stop lamp switch and the TAC module. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 23 
22 Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 26 
23 Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 27 
24 Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 29  Go to Step 28 
25 Repair the following in the Ignition 3 voltage circuit:
  • An open
  • A high resistance
  • A short to ground

Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you complete the repair?		 Go to Step 29  -
26 Replace the multifunction switch. Refer to Turn Signal Multifunction Switch Replacement .
Did you complete the replacement?		 Go to Step 29  -
27 Replace the TAC module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 29  -
28 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 29  -
29 
  1. Use the scan tool in order to clear the PCM DTCs.
  2. Operate the vehicle within the conditions for cruise control operation.
Does the cruise control system operate properly?		 System OK Go to Step 2 
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
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