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Test Description

WARNING: This page is about a different car, the 2007 Pontiac Solstice. 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. 2:  A partial malfunction in the high speed GMLAN serial data circuits uses a different procedure from a total malfunction of the high speed GMLAN data circuits. Refer to Data Link References  to identify which modules communicate on the high speed GMLAN serial data circuits.
  2. 3:  The DTC U2100 may be retrieved with a history status, but is not the cause of the present condition.
  3. 8:  Data link connector terminals 6 and 14 provide the connection to the GMLAN serial data high circuit and the GMLAN serial data low circuit respectively.
  4. 17:  The communication malfunction may have prevented diagnosis of the customer complaint.
Scan Tool Does Not Communicate with High Speed GMLAN Device

Step Action Yes No
Schematic Reference: Data Communication Schematics 
Connector End View Reference: Master Electrical Component List
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
IMPORTANT: Make sure the CANdi module is not malfunctioning. When functioning properly, the CANdi module LED will be flashing. In the event of a problem, the LED will be continually illuminated.
  1. Turn ON the ignition, with the engine OFF.
  2. Perform the Vehicle DTC Information function on the scan tool, under Computer/Integrating Systems.
Does the scan tool communicate with any module on the GMLAN serial data circuits?		 Go to Step 3  Go to Step 6 
3  Did you record any DTCs in the range of U2105 to U2177? Go to DTC U2105-U2199  Go to Step 4 
4 Did you record DTC U0001? Go to DTC U0001  Go to Step 5 
5
IMPORTANT: Turn ON the ignition, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions.
Test the high speed GMLAN serial data circuits for:
  • An intermittent short to ground
  • An intermittent short to voltage
  • An intermittent short between them
Refer to the following:Did you find and correct the condition?		 Go to Step 19  Go to Diagnostic Aids
6 Test the following circuits of the body control module (BCM) for an open or short to ground:
  • The battery positive voltage input circuits
  • The battery positive voltage output circuits
  • The ignition mode switch input circuits
  • The switched battery positive voltage circuits

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 16  Go to Step 7 
7 Test the ground circuits of the BCM for an open. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 16  Go to Step 8 
8 
  1. Turn OFF the ignition.
  2. Disconnect the scan tool from the data link connector (DLC).
  3. Inspect for poor connections at the DLC terminals 6 and 14. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Diagnostic System Check - Vehicle Go to Step 9 
9
  1. Disconnect the farthest module from the DLC that is connected to high speed GMLAN serial data circuits.
  2. Turn ON the ignition, with the engine OFF.
  3. Attempt to communicate with the BCM.
Does the scan tool communicate with the BCM?		 Go to Step 14  Go to Step 10 
10
  1. Turn OFF the ignition.
  2. Disconnect the farthest module from the DLC that is still connected to high speed GMLAN serial data circuits.
  3. Turn ON the ignition, with the engine OFF.
  4. Attempt to communicate with the BCM.
Does the scan tool communicate with the BCM?		 Go to Step 11  Go to Step 12 
11
IMPORTANT: There are two 120 ohms terminating resistors that connect between the (+) and (-) high speed GMLAN buss. Refer to Diagnostic Aids.
Test the high speed GMLAN (+) and (-) serial data circuits between the last 2 disconnected modules for:
  • A short to ground
  • A short to battery
  • A short between GMLAN (+) and GMLAN (-)-Refer to Diagnostic Aids.
Did you find and correct the condition?		 Go to Step 16  Go to Step 14 
12 Is the BCM the last module still connected to high speed GMLAN data circuits? Go to Step 13  Go to Step 10 
13
  1. Turn OFF the ignition.
  2. Disconnect the BCM.
  3. Test the high speed GMLAN serial data circuits between BCM and the previous disconnected module and between BCM and DLC for the following:
    • Short to ground
    • Short to battery
    • Short between high speed GMLAN (+) and high speed GMLAN (-)-Refer to Diagnostic Aids.
    • An open
Did you find and correct the condition?		 Go to Step 16  Go to Step 14 
14 Inspect for poor connections at the high speed GMLAN serial data circuits of the last disconnected module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 16  Go to Step 15 
15
IMPORTANT: Perform the module setup procedure if required.
Replace the last disconnected module. Refer to Control Module References for the appropriate repair instructions.Did you complete the replacement?		 Go to Step 16  -
16
  1. Reconnect all of the disconnected modules.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Wait for 10 seconds.

    The scan tool may require a power up reset before communication will occur due to a short on the high speed GMLAN serial data circuits. Turn OFF or disconnect the scan tool prior to performing this test.

  5. Select the Display DTCs function for each module.
  6. Record all of the displayed DTCs and the DTC status.
Did you record any DTCs which begin with a "U" and with a current status?		 Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 17 
17  Did you record any DTCs which do not begin with a "U"? Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 18 
18 Did you diagnose all of the DTCs? Go to Step 19  Go to Step 16 
19 Use the scan tool in order to clear the DTCs.
Did you complete the action?		 System OK -
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