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Test Description

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

  1. 6:  The class 2 serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the splice pack SP306 serial data circuits.
  2. 14:  This test isolates the splice pack SP205 serial data circuits.
  3. 20:  If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
  4. 21:  The communication malfunction may have prevented diagnosis of the customer complaint.
DTC U1300, U1301 or U1305 (5.3L)

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 Did you record U1300 or U1301, as current? Go to Step 4  Go to Step 3 
3
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 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 22  -
4
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Turn ON the ignition.
  4. Attempt to communicate with the body control module (BCM).
Does the scan tool communicate with BCM?		 Go to Step 18  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Reconnect the ECM.
  3. Disconnect the splice pack SP306.
  4. Turn ON the ignition, with the engine OFF.
  5. Retrieve the DTCs from the ECM.
Did you record U1300 or U1301, as current?		 Go to Step 8  Go to Step 6 
6  Repeat the following steps on the class 2 serial data circuits connected to the splice pack SP306 until the concern is located:
  1. Turn OFF the ignition.
  2. Using the correct terminal adapter, connect a jumper wire to the splice pack SP205 terminal of the splice pack SP306.
  3. Connect the other end of the jumper wire, using correct terminal adapter, to the terminal for the devices connected to splice pack SP306.
  4. Turn ON the ignition, with the engine OFF.
  5. Retrieve the DTCs from the ECM.

Did you record U1300 or U1301, as current?		 Go to Step 7  Go to Testing for Intermittent Conditions and Poor Connections
7
  1. Turn OFF the ignition.
  2. Disconnect the module that caused the DTC to be set.
  3. Test the class 2 serial data circuit between the splice pack SP306 and the respective module for a short to ground or a short to voltage. Turn ON the ignition, with the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 18 
8
  1. Turn OFF the ignition.
  2. Disconnect the splice pack SP205.
  3. Turn ON the ignition, with the engine OFF.
  4. Retrieve DTCs from ECM.
Did you record U1300 or U1301, as current?		 Go to Step 9  Go to Step 12 
9
  1. Turn OFF the ignition.
  2. Disconnect the theft deterrent control module (VTD), if equipped or disconnect the BCM, if not equipped with VTD.
  3. Turn ON the ignition, with the engine OFF.
  4. Retrieve DTCs from ECM.
Did you record U1300 or U1301, as current?		 Go to Step 11  Go to Step 10 
10
  1. Turn OFF the ignition.
  2. Test the class 2 serial data circuit between VTD, if equipped or BCM if not equipped with VTD and splice pack SP205 for a short to ground or a short to voltage. Refer to Circuit Testing andWiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 16 
11
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the class 2 serial data circuit between the ECM and VTD, if equipped or BCM if not equipped with VTD, for a short to ground or a short to voltage. Turn ON the ignition, with the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
  4. Test the class 2 serial data circuit between the ECM and splice pack SP306 for a short to ground or a short to voltage. Turn ON the ignition, with the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 16 
12
  1. Turn OFF the ignition.
  2. Using the correct terminal adapter, connect a jumper wire to the ECM terminal of the splice pack SP205.
  3. Connect the other end of the jumper wire, using correct terminal adapter, to the splice pack SP306 terminal of the splice pack SP205.
  4. Turn ON the ignition, with the engine OFF.
  5. Retrieve DTCs from ECM.
Did you record U1300 or U1301, as current?		 Go to Step 13  Go to Step 14 
13
  1. Turn OFF the ignition.
  2. Repair the short to ground or short to voltage in the class 2 serial data circuit between the splice pack SP205 and the splice pack SP306. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  -
14  Repeat the following steps on the class 2 serial data circuits connected to the splice pack SP205 until the concern is located:
  1. Turn OFF the ignition.
  2. Leave the jumper wire connected to the ECM terminal of the splice pack SP205.
  3. Connect the other end of the jumper wire, using correct terminal adapter, to the terminal for the devices connected to splice pack SP205.
  4. Turn ON the ignition, with the engine OFF.
  5. Retrieve DTCs from ECM.

Did you record U1300 or U1301, as current?		 Go to Step 15  Go to Testing for Intermittent Conditions and Poor Connections
15
  1. Turn OFF the ignition.
  2. Disconnect the module that caused the DTC to be set.
  3. Test the class 2 serial data circuit between the splice pack SP205 and the respective module for a short to ground or a short to voltage. Turn ON the ignition, with the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 18 
16 Inspect for poor connections at the class 2 serial data circuit of the VTD, if equipped or BCM, if not equipped with VTD. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 17 
17 Replace the VTD, if equipped or BCM, if not equipped with VTD. Refer to Control Module References for replacement, setup and programming.
Did you complete the replacement?		 Go to Step 20  -
18 Inspect for poor connections at the class 2 serial data circuit of the last disconnected module. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 19 
19 Replace the last disconnected module. Refer to Control Module References for replacement, setup and programming.
Did you complete the replacement?		 Go to Step 20  -
20 
  1. Reconnect all of the disconnected modules and splice packs.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Retrieve the DTCs.
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 21 
21  Did you record any DTCs which do not begin with a "U"? Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 22 
22 Use the scan tool in order to clear the DTCs.
Did you complete the action?		 System OK -
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