FILM-INFORMATION 3622106 - Caterpillar

Illustration 1 g01272867
Schematic for the tachometer circuit
Illustration 2 g01272878
Schematic for the tachometer circuit
Test Step 1. Inspect the Electrical Connectors and the Wiring
Illustration 3 g01152498
Terminal locations on the P1 connector
(P1-38) Tachometer+
(P1-39) Tachometer-
Thoroughly inspect ECM connector J1/P1 and the terminals for the tachometer. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Refer to Illustration 3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the terminals for the tachometer:
Check the allen head screw on each of the ECM connectors for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and wiring for abrasion and for pinch points from the tachometer