Usage:
3126B (7AS1-Up, 8YL1-Up) Truck Engines
Problem: The Injection Actuation Pressure Driver Test does not function properly in some versions of 3126B (7AS) Truck Engine software.
Symptom: There is a defect in the engine software for 3126B that will produce false results when running the Injection Actuation Pressure Driver test. This test is performed in procedure PC37 in Steps 5 and 7. The test requires the test lamp be connected and the drive test cycled on and off. The test lamp should go on and off. The driver test is always running so the test light is always on. This leads to ECM replacements. If the test light is on, DO NOT REPLACE THE ECM. Software versions affected are JUN98, OCT98, JAN99 and APR99.
Corrective Action: This defect is corrected in the JUN99 Software for 7AS Serial Numbers (Field Service Only) and JUL99 for 8YL Serial Numbers. This software was released to the Caterpillar Mailbox in August.