For 1990-2009 cars

## Scan Tool Does Not Communicate with UART Data Line Buick

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Data Link Communications System Check? | -- | Go to Step 2 | Go to Data Link Communications System Check
2 |

1. Connect the Scan Tool to another vehicle of the same model and year in order to ensure proper operation of the Scan Tool .
2. Turn the ignition switch to the RUN position.
3. Attempt to establish communication with the UART serial data line.

Does the Scan Tool communicate with the UART serial data line?

--

Go to Step 4

Go to Step 3

3 | The scan tool may be malfunctioning. Refer to the scan tool instruction manual in order to ensure that the Scan Tool is functioning. Does the Scan Tool operate properly? | -- | Go to Data Link Communications System Check | --
4 |

1. Connect the Scan Tool to the original vehicle.
2. Verify that the Scan Tool connections are clean and tight.

Is the terminal contact between the data link connector (DLC) Scan Tool OK?

--

Go to Step 6

Go to Step 5

5 | Repair the terminal contact between the Scan Tool and the DLC. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
6 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the electronic brake and traction control module (EBTCM).
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster using the Scan Tool .

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 7

Go to Step 8

7 | Replace the EBTCM. Refer to Electronic Brake and Traction Control Module Replacement in Antilock Brake System. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
8 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the heater and A/C programmer connector C2.
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 9

Go to Step 12

9 | Test CKT 800 (TAN) between the heater and A/C programmer connector C2, terminal C8, and the EBTCM connector terminal 23 for a short to ground or battery positive voltage (B+). Did you find the condition? | -- | Go to Step 10 | Go to Step 11
10 | Repair the short in CKT 800 (TAN). Did you complete the repair? | -- | Go to Data Link Communications System Check | --
11 | Replace the heater and A/C programmer. Refer to Programmer Replacement in HVAC System--Automatic. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
12 | Is the vehicle equipped with the cellular telephone module? | -- | Go to Step 13 | Go to Step 15
13 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the cellular telephone module.
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 14

Go to Step 15

14 | Replace the cellular telephone module. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
15 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 16

Go to Step 17

16 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement in SIR. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
17 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the powertrain control module (PCM).
3. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 18

Go to Step 19

18 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls--3.8L. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
19 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the instrument cluster connector C1.
3. Reconnect the PCM.
4. Turn the ignition switch to the ON position.
5. Attempt to establish communication with the PCM.

Does the Scan Tool communicate with the PCM?

--

Go to Step 21

Go to Step 20

20 | Repair the open, the short to ground, or the short to battery positive voltage (B+) in CKT 800 (TAN). Did you complete the repair? | -- | Go to Data Link Communications System Check | --
21 | Test CKT 800 (TAN) between the instrument cluster connector C1, terminal E11, and the EBTCM connector terminal 42 for a short to ground, or a short to battery positive voltage (B+). Did you find the condition? | -- | Go to Step 20 | Go to Step 22
22 | Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Did you complete the repair? | -- | Go to Data Link Communications System Check | --

## Scan Tool Does Not Communicate with UART Data Line Oldsmobile

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Data Link Communications System Check? | -- | Go to Step 2 | Go to Data Link Communications System Check
2 |

1. Connect the Scan Tool to another vehicle of the same model and year in order to ensure proper operation of the Scan Tool .
2. Turn the ignition switch to the RUN position.
3. Attempt to establish communication with the UART serial data line.

Does the Scan Tool communicate with the UART serial data line?

--

Go to Step 4

Go to Step 3

3 | The scan tool may be malfunctioning. Refer to the scan tool instruction manual in order to ensure that the Scan Tool is functioning. Does the Scan Tool operate properly? | -- | Go to Data Link Communications System Check | --
4 |

1. Connect the Scan Tool to the original vehicle.
2. Verify that the Scan Tool connections are clean and tight.

Is the terminal contact between the data link connector (DLC) and the Scan Tool OK?

--

Go to Step 6

Go to Step 5

5 | Repair the terminal contact between the Scan Tool and the DLC. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
6 |

1. Turn OFF the ignition.
2. Disconnect the electronic brake and traction control module (EBTCM).
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster using the Scan Tool .

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 7

Go to Step 8

7 | Replace the EBTCM. Refer to Electronic Brake and Traction Control Module Replacement in Antilock Brake System. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
8 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the heater and A/C programmer connector C2.
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 9

Go to Step 12

9 | Test CKT 800 (TAN) between the heater and A/C programmer connector C2, terminal C8, and the EBTCM connector terminal 23 for a short to ground or battery positive voltage (B+). Did you find the condition? | -- | Go to Step 10 | Go to Step 11
10 | Repair the short in CKT 800 (TAN). Did you complete the repair? | -- | Go to Data Link Communications System Check | --
11 | Replace the heater and A/C programmer. Refer to Programmer Replacement in HVAC Systems--Automatic. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
12 | Is the vehicle equipped with the cellular telephone module? | -- | Go to Step 13 | Go to Step 15
13 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the cellular telephone module.
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 14

Go to Step 15

14 | Replace the cellular telephone module. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
15 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
3. Turn the ignition switch to the RUN position.
4. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 16

Go to Step 17

16 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement in SIR. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
17 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the powertrain control module (PCM).
3. Attempt to establish communication with the instrument cluster.

Does the Scan Tool communicate with the instrument cluster?

--

Go to Step 18

Go to Step 19

18 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls--3.8L Did you complete the repair? | -- | Go to Data Link Communications System Check | --
19 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the heater and A/C control.
3. Reconnect the PCM.
4. Turn the ignition switch to the ON position.
5. Attempt to establish communication with the PCM.

Does the Scan Tool communicate with the PCM?

--

Go to Step 20

Go to Step 21

20 | Replace the heater and A/C control. Refer to Control Assembly Replacement in HVAC System--Automatic Did you complete the repair? | -- | Go to Data Link Communications System Check | --
21 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the instrument cluster connector C1.
3. Turn the ignition switch to the ON position.
4. Attempt to establish communication with the PCM.

Does the Scan Tool communicate with the PCM?

--

Go to Step 22

Go to Step 27

22 | Test CKT 1061 (ORN/BLK) for a short to ground, or battery positive voltage (B+) between the instrument cluster connector C1, terminal D8 and the DLC connector terminal 1. Did you find the condition? | -- | Go to Step 26 | Go to Step 23
23 | Test CKT 1061 (ORN/BLK) for a short to ground, or battery positive voltage (B+) between the instrument cluster connector C1, terminal C8 and the heater and A/C control connector terminal A3. Did you find the condition? | -- | Go to Step 26 | Go to Step 24
24 | Test CKT 800 (TAN) for a short to ground or battery positive voltage (B+) between the instrument cluster connector C1, terminal D9 and the EBTCM connector terminal 42. Did you find the condition? | -- | Go to Step 25 | Go to Step 26
25 | Repair the short to ground or battery positive voltage (B+) in CKT 800 (TAN). Did you complete the repair? | -- | Go to Data Link Communications System Check | --
26 | Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Did you complete the repair? | -- | Go to Data Link Communications System Check | --
27 | Repair the open, short to ground, or battery positive voltage (B+) in CKT 800 (TAN). Did you complete the repair? | -- | Go to Data Link Communications System Check | --
28 | Repair the short to ground or battery positive voltage (B+) in CKT 1061 (ORN/BLK). Did you complete the repair? | -- | Go to Data Link Communications System Check | --