Test Description

The numbers below refer to the step numbers on the diagnostic table. See Fig 1 and Fig 2 .

1. 2
   
   This test checks if communications can be established between the scan tool and the body control module (BCM). If the scan tool cannot communicate with the BCM, refer to DIAGNOSTIC SYSTEM CHECK - THEFT DETERRENT .
2. 3
   
   This test checks for any opens in the serial data circuit between the powertrain control module (PCM) and the BCM. This also checks for any intermittent malfunctions associated with the serial data circuit.
3. 4
   
   This step is to determine if the condition that set DTC is still present. The engine must be cranked in order to set this DTC. If the condition is present, the engine will start and then stall, indicating the PCM is disabling fuel.
4. 7
   
   Use a scan tool to clear and check for any DTCs in all the modules connected to the Class 2 Serial Data circuit, such as the PCM, BCM, automatic temperature control (ATC), and body control module (BCM).
Fig 1: DTC P1626 Diagnostic Table (Steps 1-4)
Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC P1626 Diagnostic Table (Steps 5-9)
Courtesy of GENERAL MOTORS CORP.