For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Install the scan tool. Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Inoperative in Data Link Communications
2 |

1. Turn On the ignition, with the engine OFF.
2. Attempt to establish communication with the radio.

Does the scan tool communicate with the radio?

Go to Step 3

Go to Step 4

3 | Select DTC Information for the radio. Does the scan tool display any current B-Type DTCs? | Go to DTC List | Go to Step 5
4 | Attempt to establish communications with the other modules connected to the Class 2 data link. (If using a Tech 2, the Class 2 Message Monitor feature can be used to obtain this information.) Are there any modules on the Class 2 data link which are communicating? | Go to Step 6 | Go to Scan Tool Does Not Communicate with Class 2 Data Line in Data Link Communications
5 | Does the scan tool display any current U-Type DTCs? | Go to Diagnostic Trouble Code (DTC) List in Data Link Communications | Go to Step 7
6 |

1. Remove and inspect the RADIO BATT GUARD fuse for an open.
2. Inspect and test the battery feed circuit at terminal F1 for proper voltage (11-13 V).
3. Make necessary repairs.

Did you find and correct any conditions?

Go to Step 2

Go to Step 8

7 | Does the scan tool display any history B-Type or U-Type DTCs? | Go to Step 9 | Go to Radio/Audio System Check
8 | Replace the radio. Is the replacement complete? | Go to Radio/Audio System Check | --
9 |

1. Review the appropriate DTC diagnostic table for the history DTC.
2. Review the diagnostic aids and the conditions for setting the DTC.

Did any DTC set as a current DTC, while attempting to locate the cause of the history DTC?

Go to the appropriate DTC List

Go to Radio/Audio System Check