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Home >> Saturn >> 2007 >> Ion Red Line >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Data Communication System >> Diagnostic Information and Procedures >> Scan Tool Does Not Communicate with Class 2 Device >> Test Description

Test Description

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

  1. 2:  A partial loss of communication in the class 2 serial data circuit uses a different procedure than a total loss of communication of the class 2 serial data circuit.
  2. 4:  The following DTCs may be retrieved with a history status. These DTCs are not the cause of the present condition.
    • U1300
    • U1301
    • U1305
  3. 6:  A State of Health (SOH) DTC with a history status may be present along with a U1000 or U1255 with a current status. This indicates that the malfunction occurred when the ignition was on.
  4. 10:  Normal class 2 serial data communication cannot take place until the power mode master (PMM) module sends the appropriate power mode message. If the PMM does not send a wake-up message, other modules on the class 2 serial data circuit may not communicate.
  5. 12:  This step will isolate a wiring problem or a module malfunction.
  6. 13:  An open circuit at this point will cause a loss of communication with the vehicle.
  7. 14:  This step analyzes the specific branch circuit for a malfunction.
  8. 19:  If there are no current DTCs that begin with the letter "U", the communication concern has been repaired.
  9. 20:  The communication concern may have prevented diagnosis of the customer complaint.
Scan Tool Does Not Communicate with Class 2 Device

Step Action Yes No
Schematic Reference: Data Communication Schematics 
Connector End View Reference: Master Electrical Component List
1 Install a scan tool.
Does the scan tool power up?		 Go to Step 2  Go to Scan Tool Does Not Power Up 
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to communicate with each module on the class 2 serial data circuit. If using a Tech 2, obtain this information using the class 2 Message Monitor feature.
Does the scan tool communicate with any module on the class 2 serial data circuit?		 Go to Step 3  Go to Step 8 
3
  1. Select the Display DTCs function for each module. If using a Tech 2, use the class 2 DTC Check feature in order to determine which modules do have DTCs set.
  2. Record all of the displayed DTCs, the DTC status and the module which set the DTC.
Did you record any DTCs in the range of U1000 to U1305?		 Go to Step 4  Go to Step 7 
4  Are history DTCs U1300, U1301 or U1305 retrieved from any module? Go to Step 5  Go to Step 6 
5
IMPORTANT: Turn the ignition ON, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions.
Test the class 2 serial data circuit for an intermittent short to ground or an intermittent short to voltage. Refer to the following:Did you find and correct the condition?		 Go to Step 18  Go to Step 6 
6  Are U1000 or U1255 the only DTCs displayed in the previously specified range? Go to DTC U1000 and U1255  Go to DTC U1001-U1254 
7 Diagnose the non communicating module by using the DTC U1001 - U1254 Lost Communications with XXX procedure for the module which is not communicating. The DTC U1001 - U1254 Lost Communications with XXX procedure will determine which module is not communicating. Refer to DTC U1001-U1254 .
Did you complete the action?		 Go to Diagnostic System Check - Vehicle -
8
  1. Turn the ignition OFF.
  2. Disconnect the scan tool from the data link connector (DLC).
  3. Inspect for poor connections and terminal tension at the DLC. 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 Test the ground circuits of the DLC for an open or high resistance. 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 10 
10 
  1. Isolate the power mode master (PMM) module from all other modules on the class 2 serial data circuit by backing out only the class 2 serial data terminals from the PMM harness connectors, except for the one class 2 serial data circuit that is routed to the DLC, pin 2. To identify which module is the PMM refer to Body Control System Description and Operation .
  2. Connect all of the PMM harness connectors with the extracted class 2 serial data circuit terminals.
  3. Turn the ignition ON, with the engine OFF.
  4. Attempt to communicate with the PMM.
Does the scan tool communicate with the PMM?		 Go to Step 12  Go to Step 11 
11
  1. Test the class 2 serial data circuits between the DLC and the PMM for the following conditions. Turn ON the ignition when testing for a short to voltage:
    • High resistance
    • Open
    • Short to ground
    • Short to voltage
  2. Test the following circuits of the PMM for an open or high resistance:
    • The battery positive voltage input circuits
    • The battery positive voltage output circuits
    • The ignition voltage input circuits
    • The ignition voltage output circuits
    • The switched battery positive voltage supply circuits
    • The ground circuits
Refer to Circuit Testing and Wiring Repairs .Did you find and correct the condition?		 Go to Step 18  Go to Step Step 17 
12  Perform the following for each class 2 serial data branch circuit, in order to determine if the concern is located within the class 2 serial data branch circuits or the modules connected to the class 2 bus:
  1. Turn the ignition OFF.
  2. One at a time, replace each terminal in the PMM harness connectors.
  3. Turn the ignition ON, with the engine OFF.
  4. Attempt to communicate with any module connected to the class 2 serial data branch circuit after reinstalling it's class 2 serial data terminal.
  5. Record which branch of the class 2 serial data circuit causes a loss of communication if one occurs in the above items.

Does the scan tool communicate with all modules connected to the class 2 serial data circuit after all the branch circuits have been reconnected?		 Go to Step 13  Go to Step 14 
13  Inspect for poor connections and terminal tension at the harness connector of the PMM harness connector that contains the discreet class 2 serial data circuit for the DLC.
Did you complete the action?		 Go to Step 18  -
14 
  1. Turn the ignition OFF.
  2. Using the record made in step 12, identify each module on that branch of the class 2 serial data circuit and disconnect there harness connectors containing the class 2 serial data circuits.
  3. Using the record made in step 12 again, test the branch circuits that caused a No Comm with class 2 for the following. Turn the ignition ON when testing for a short to voltage or short to ground.
Did you find and correct the problem?		 Go to Step 18  Go to Step 15 
15 The concern is a malfunctioning module on the class 2 serial data branch circuit recorded in step 12.
  1. Turn the ignition OFF.
  2. One at a time, starting with the first module on the malfunctioning class 2 serial data branch circuit closest to the PMM, start attaching modules back onto that branch circuit.
  3. Turn the ignition ON, with the engine OFF.
  4. Attempt to communicate with the reinstalled modules connected to the malfunctioning branch.
  5. Repeat items 1 through 4 attempting to lose communication. If communication is lost, record the last module reconnected proceed down the table and discontinue the repeating of items 1 through 4.

Does the scan tool communicate with all the modules connected to the class 2 serial data circuit?		 Go to Step 18  Go to Step 1 
16 Inspect for poor connections and terminal tension at the harness connector of the reconnected module that causes a loss of communication. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 18  Go to Step 17 
17 Replace the suspect module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 18  -
18
  1. Connect all of the modules.
  2. Connect all the connectors.
  3. Install a scan tool.
  4. Turn the ignition ON leaving the engine OFF.
    5. IMPORTANT: The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn off or disconnect the scan tool before you display DTCs.
  5. Wait for 10 seconds.
  6. Select the display DTCs function for each module. If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set.
  7. Record all of the displayed DTCs and the DTC status.
Did your record any DTCs which begin with a letter U and with a current status?		 Go to Step 20  Go to Step 19 
19  Did you record any DTCs which do not begin with a letter "U"? Go to Step 20  Go to Step 22 
20  Diagnose the DTCs as directed by the diagnostic procedures for the particular module or concern.
Did you complete the action?		 Go to Step 21  -
21 Did you diagnose all of the DTCs? Go to Step 22  Go to Step 20 
22 Clear the DTCs using the scan tool.
Did you complete the action?		 Go to Diagnostic System Check - Vehicle -
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