C 1500 Yukon 2WD V8-4.8L VIN V (2000)
CIRCUIT DESCRIPTION
Use a properly functioning scan tool with the diagnostic tables in this system. DO NOT use the Clear Info function unless instructed by a diagnostic
procedure.
IMPORTANT: This vehicle, equipped with a Powertrain Control Module (PCM), utilizes an Electrically Erasable Programmable Read Only
Memory (EEPROM). Program the new PCM when the diagnostics call for replacement of the PCM. Refer to Powertrain Control Module (PCM)
Replacement. When the PCM or Body Control Module (BCM) is replaced the PCM Password Learn procedure must be performed. Refer to DTC
P1631 Theft Deterrent Start Enable Signal Not Correct. See: Testing and Inspection/Diagnostic Trouble Code Tests and Associated Procedures/P
Code Charts/P1631
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. An engine that just cranks and does not attempt to start indicates that the PCM is not powered-up.
5. This step is checking for a B+ supply to the Data Link Connector (DLC).
6. A ground must be available at both terminals for the scan tool to function properly.
9. A no start condition occurs when the fuses for the battery or ignition positive voltage circuits is open. The Malfunction Indicator Lamp (MIL) is
inoperative when the battery and ignition positive voltage circuit fuses open. Inspect the circuits for being grounded when either of these fuses
open.
12. The scan tool does not communicate when the C100 connector is open. The C100 connector is located under the underhood electrical center.
14. If the test lamp does not illuminate for a circuit, inspect the fuse for being open. If the fuse is open, inspect the circuit for a short to ground.
15. Inspect for an open ground circuit. Inspect G103 located on the right rear of the engine block for an open or for a poor connection.
16. Inspect for an open fuse that supplies the DLC. If the fuse is open, repair the grounded circuit.
