For 1990-2009 cars

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Data Link Connector Diagnostic System Check performed? | -- | Go to Step 2 | Go to Data Link Communications System Check
2 |

1. Connect the scan tool to another vehicle of the same model year in order to ensure proper operation of the scan tool.
2. Turn the ignition switch to RUN.
3. Attempt to establish communication with the vehicle.

Does the scan tool communicate with the vehicle?

--

Go to Step 4

Go to Step 3

3 | The scan tool may be malfunctioning. Refer to the scan tool instruction manual. 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 DLC and the scan tool OK?

--

Go to Step 6

Go to Step 5

5 | Repair the terminal contact at the DLC. Is the repair complete? | -- | Go to Data Link Communications System Check | --
6 |

1. Connect the scan tool.
2. Turn the ignition switch to RUN, with the engine OFF.

Does the scan tool turn ON?

--

Go to Step 12

Go to Step 7

7 | Inspect for voltage between DLC terminal 16 and the chassis ground. Is the voltage within the specified range? | 10-15 V | Go to Step 9 | Go to Step 8
8 | Repair the open or the short to ground in CKT 40 (ORN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
9 | Inspect for voltage between DLC terminal 16 and terminal 5. Is the voltage within the specified range? | 10-15 V | Go to Step 11 | Go to Step 10
10 | Repair the open in CKT 451 (BLK/WHT). Is the repair complete? | -- | Go to Data Link Communications System Check | --
11 | Repair the open in CKT 1250 (BLK) Is the repair complete? | -- | Go to Data Link Communications System Check | --
12 | Using a DMM, check for voltage from DLC terminal 9 to ground. Is the voltage within the specified range? | 10-15 V | Go to Step 15 | Go to Step 13
13 | Using a DMM, measure the resistance from DLC terminal 9 to ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 28 | Go to Step 14
14 | Repair the open in CKT 800 (TAN) between DLC terminal 9 and S226. Is the repair complete? | -- | Go to Data Link Communications System Check | --
15 |

1. Disconnect the EBTCM.
2. Inspect for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 17

Go to Step 16

16 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
17 |

1. Disconnect the PCM.
2. Inspect for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 19

Go to Step 18

18 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
19 |

1. Disconnect the heater and the A/C programmer.
2. Inspect for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 21

Go to Step 20

20 | Inspect for voltage from the heater and A/C programmer connector terminal E11 to ground. Is the voltage within the specified range? | 10-15 V | Go to Step 41 | Go to Step 42
21 |

1. Disconnect the transmission position decoder module.
2. Inspect for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 23

Go to Step 22

22 | Replace the transmission position decoder module. Is the repair complete? | -- | Go to Data Link Communications System Check | --
23 |

1. Disconnect the instrument cluster.
2. Inspect voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 25

Go to Step 24

24 | Replace the instrument cluster. Is the repair complete? | -- | Go to Data Link Communications System Check | --
25 |

1. Disconnect the SDM.
2. Inspect for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 27

Go to Step 26

26 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
27 | Repair the short to battery positive voltage (B+) in CKT 800 (TAN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
28 |

1. Disconnect the EBTCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 30

Go to Step 29

29 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
30 |

1. Disconnect the PCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 32

Go to Step 31

31 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
32 |

1. Disconnect the heater and A/C programmer.
2. Measure the resistance from DLC terminal 9 to ground.

Is resistance within the specified range?

0-5 ohms

Go to Step 34

Go to Step 33

33 | Measure the resistance from the heater and A/C programmer connector terminal E11 and ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 43 | Go to Step 42
34 |

1. Disconnect the transmission position decoder module.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 36

Go to Step 35

35 | Replace the transmission position decoder module. Is the repair complete? | -- | Go to Data Link Communications System Check | --
36 |

1. Disconnect the instrument cluster.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 38

Go to Step 37

37 | Replace the instrument cluster. Is the repair complete? | -- | Go to Data Link Communications System Check | --
38 |

1. Disconnect the SDM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 40

Go to Step 39

39 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
40 | Repair the short to ground in CKT 800 (TAN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
41 | Repair the short to battery positive voltage (B+) in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --
42 | Replace the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --
43 | Repair the short to ground in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Data Link Connector System Check performed? | -- | Go to Step 2 | Go to Data Link Communications System Check
2 |

1. Connect the scan tool to another vehicle of the same model year in order to ensure proper operation of the scan tool.
2. Turn the ignition switch to RUN.
3. Attempt to establish communication with the vehicle.

Does the scan tool communicate with the vehicle?

--

Go to Step 4

Go to Step 3

3 | The scan tool may be malfunctioning. Refer to the scan tool instruction manual. 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 the scan tool connections are clean and tight.

Is the terminal contact between the DLC and the scan tool OK?

--

Go to Step 6

Go to Step 5

5 | Repair the terminal contact at the DLC. Is the repair complete? | -- | Go to Data Link Communications System Check | --
6 |

1. Connect the scan tool.
2. Turn the ignition switch to RUN, with the engine OFF.

Will the scan tool turn ON?

--

Go to Step 12

Go to Step 7

7 | Inspect for voltage between DLC terminal 16 and chassis ground. Is the voltage within the specified range? | 10-15 V | Go to Step 9 | Go to Step 8
8 | Repair the open or the short to ground in CKT 40 (ORN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
9 | Inspect for voltage between DLC terminal 16 and terminal 5. Is the voltage within the specified range? | 10-15 V | Go to Step 11 | Go to Step 10
10 | Repair the open in CKT 451 (BLK/WHT). Is the repair complete? | -- | Go to Data Link Communications System Check | --
11 | Repair the open in CKT 1250 (BLK) Is the repair complete? | -- | Go to Data Link Communications System Check | --
12 | Using a DMM, check for voltage from DLC terminal 9 to ground. Is the voltage within the specified range? | 10-15 V | Go to Step 15 | Go to Step 13
13 | Measure the resistance from DLC terminal 9 to ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 26 | Go to Step 14
14 | Repair the open in CKT 800 (TAN) between DLC terminal 9 and S226. Is the repair complete? | -- | Go to Data Link Communications System Check | --
15 |

1. Disconnect the EBTCM.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 17

Go to Step 16

16 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
17 |

1. Disconnect the PCM.
2. Measure for voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 19

Go to Step 18

18 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
19 |

1. Disconnect the heater and A/C programmer.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 21

Go to Step 20

20 | Measure the voltage from the heater and A/C programmer connector terminal C11 and ground. Is the voltage within the specified range? | 10-15 V | Go to Step 37 | Go to Step 38
21 |

1. Disconnect the SDM.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 23

Go to Step 22

22 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
23 |

1. Disconnect the shift select switch.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 25

Go to Step 24

24 | Replace the shift select switch. Is the repair complete? | -- | Go to Data Link Communications System Check | --
25 | Repair the short to battery positive voltage (B+) in CKT 800 (TAN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
26 |

1. Disconnect the EBTCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 28

Go to Step 27

27 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
28 |

1. Disconnect the PCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 30

Go to Step 29

29 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
30 |

1. Disconnect the heater and A/C programmer.
2. Measure the resistance from DLC terminal 9 to ground.

Is resistance within the specified range?

0-5 ohms

Go to Step 32

Go to Step 31

31 | Measure the resistance from the heater and A/C programmer connector C11 to ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 39 | Go to Step 38
32 |

1. Disconnect the SDM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 34

Go to Step 33

33 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
34 |

1. Disconnect the shift select switch.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

--

Go to Step 36

Go to Step 35

35 | Replace the shift select switch. Is the repair complete? | -- | Go to Data Link Communications System Check | --
36 | Repair the short to ground in CKT 800 (TAN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
37 | Repair the short to battery positive voltage (B+) in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --
38 | Replace the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --
39 | Repair the short to ground in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Data Link Connector System Check performed? | -- | Go to Step 2 | Go to Data Link Communications System Check
2 |

1. Connect the scan tool to another vehicle of the same model year in order to ensure proper operation of the scan tool.
2. Turn the ignition switch to RUN.
3. Attempt to establish communication with the vehicle.

Does the scan tool communicate with the vehicle?

--

Go to Step 4

Go to Step 3

3 | The scan tool may be malfunctioning. Refer to the scan tool instruction manual. 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 the scan tool connections are clean and tight.

Is the terminal contact between the DLC and the scan tool OK?

--

Go to Step 6

Go to Step 5

5 | Repair the terminal contact at the DLC. Is the repair complete? | -- | Go to Data Link Communications System Check | --
6 |

1. Connect the scan tool.
2. Turn the ignition switch to RUN, with the engine off.

Does the scan tool turn on?

--

Go to Step 12

Go to Step 7

7 | Measure the voltage between DLC terminal 16 and chassis ground. Is the voltage within the specified range? | 10-15 V | Go to Step 9 | Go to Step 8
8 | Repair the open or the short to ground in CKT 40 (ORN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
9 | Measure the voltage between DLC terminal 16 and terminal 5. Is the voltage within the specified range? | 10-15 V | Go to Step 11 | Go to Step 10
10 | Repair the open in CKT 451 (BLK/WHT). Is the repair complete? | -- | Go to Data Link Communications System Check | --
11 | Repair the open in CKT 1250 (BLK) Is the repair complete? | -- | Go to Data Link Communications System Check | --
12 | Using a DMM, measure the voltage from DLC terminal 9 to ground. Is the voltage within the specified range? | 10-15 V | Go to Step 15 | Go to Step 13
13 | Using a DMM, measure the resistance from DLC terminal 9 to ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 24 | Go to Step 14
14 | Repair the open in CKT 800 (TAN) between DLC terminal 9 and S226. Is the repair complete? | -- | Go to Data Link Communications System Check | --
15 |

1. Disconnect the EBTCM.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 17

Go to Step 16

16 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
17 |

1. Disconnect the PCM.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 19

Go to Step 18

18 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
19 |

1. Disconnect the heater and A/C programmer.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 21

Go to Step 20

20 | Measure the voltage from the heater and A/C programmer connector terminal E11 to ground. Is the voltage within the specified range? | 10-15 V | Go to Step 34 | Go to Step 33
21 |

1. Disconnect the SDM.
2. Measure the voltage from DLC terminal 9 to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 23

Go to Step 22

22 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
23 | Repair the short to battery positive voltage (B+) in CKT 800 (TAN). Is the repair complete? | -- | Go to Data Link Communications System Check | --
24 |

1. Disconnect the EBTCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 26

Go to Step 25

25 | Replace the EBTCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
26 |

1. Disconnect the PCM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 28

Go to Step 27

27 | Replace the PCM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
28 |

1. Disconnect the heater and A/C programmer.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified?

0-5 ohms

Go to Step 30

Go to Step 29

29 | Measure the resistance from the heater and A/C programmer connector terminal E11 to ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 30 | Go to Step 29
30 |

1. Disconnect the SDM.
2. Measure the resistance from DLC terminal 9 to ground.

Is the resistance within the specified range?

0-5 ohms

Go to Step 32

Go to Step 31

31 | Replace the SDM. Is the repair complete? | -- | Go to Data Link Communications System Check | --
32 | Repair the short to ground in CKT 800 (TAN/BLK). Is the repair complete? | -- | Go to Data Link Communications System Check | --
33 | Replace the heater and A/C programmer. Is the repair complete? | -- | Refer to Data Link Communications System Check | --
34 | Repair the short to battery positive voltage in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --
35 | Repair the short to ground in CKT 800 (TAN) between the EBTCM and the heater and A/C programmer. Is the repair complete? | -- | Go to Data Link Communications System Check | --