Test Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

2. A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit.
3. DTCs U1300, U1301, or U1305 may be retrieved with a history status. These DTCs are not the cause of the present condition.
6. A state of health DTC with a history status may be present along with a U1000 having a current status. This indicates the malfunction occurred when the ignition was ON.
7. Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
8. An open in the class 2 serial data circuit between the DLC and the modules will prevent the scan tool from communicating with any module.
9. This condition will not set a DTC. 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 wiring for a short, make sure there is not a module connected to the wire being tested. This test isolates the PCM class 2 serial data circuit.
10. This test isolates the PCM class 2 serial data circuit.
11. This test isolates the SDM class 2 serial data circuit.
12. This test isolates the VIU class 2 serial data circuit.
13. This test isolates the PK3 class 2 serial data circuit.
16. If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
17. The communication malfunction may have prevented diagnosis of the customer complaint.

Fig 1: Scan Tool Does Not Communicate With Class 2 Device (1 Of 2)
Courtesy of GENERAL MOTORS CORP.

Fig 2: Scan Tool Does Not Communicate With Class 2 Device (2 Of 2)
Courtesy of GENERAL MOTORS CORP.