Cummins 3923129 — Genuine Crankshaft Position (Engine Speed) Sensor

MPN: 3923129  |  Also Known As: engine speed sensor, CKP sensor, crank sensor  |  Cross-Ref (ID): Mopar 4882763

Restore accurate RPM and crank position signals on your second-gen. The genuine Cummins 3923129 crankshaft position / engine speed sensor is the OE unit for 1997–1998 Ram 2500/3500 5.9L 12-valve applications that use the rectangular (square) 3-pin connector. It reads the damper at the front of the engine and feeds the ECM/PCM for idle quality, tachometer, charging strategy, and transmission logic.

Features & Benefits

• OE signal quality for stable idle, correct tach operation, and proper shifting (auto trans).
• Direct-fit sensor with factory connector and mounting pattern—no splicing.
• Durable pickup & housing for heat, vibration, and oil mist exposure near the damper.
• Fixes common symptoms: erratic/no tach, stalling, hard starts, or CKP-related DTCs (after wiring checks).
• Genuine Cummins part number for traceability and long service life.

Verified Fitment (Automotive)

Specifications

• Type: Inductive crankshaft position / engine speed sensor
• OE Part Number: 3923129
• Connector: 3-pin rectangular (square) plug
• Mounting: Front cover/damper area; reads damper teeth
• Quantity Required: 1 per engine

Often Paired With

• Early-style CKP (round plug): Cummins 3924432 (’94–early ’97)
• CKP pigtail/repair connector (if your connector is brittle or oil-soaked)
• Harmonic balancer (damper): Cummins 3924435 (inspect while servicing)

What’s In The Box

• (1) Genuine Cummins Crankshaft Position / Engine Speed Sensor (3923129)

Installation Tips

• Key-off; disconnect negative battery cable. Safely raise front if needed for access.
• Clean the mounting area near the damper; avoid metal debris on the pickup face.
• Route the harness away from moving belts; ensure secure connector engagement.
• After install, verify stable tach reading and clear any stored CKP codes.

FAQ

WILL THIS FIT MY 1997–1998 12-VALVE RAM?

Yes—3923129 is the OE CKP/engine speed sensor for 1997–1998 trucks that use the rectangular 3-pin connector.

HOW DO I KNOW WHICH SENSOR I NEED ON A 1997 TRUCK?

Check the connector: round = 3924432 (early style), rectangular = 3923129 (late ’97–’98).

WHERE IS THE SENSOR LOCATED?

At the front of the engine, reading the harmonic balancer/damper for crank position and RPM.

WHAT SYMPTOMS POINT TO A FAILING CKP?

Intermittent/no tach, stalling, hard starts, or CKP-related DTCs. Always inspect wiring and grounds first.

IS THIS A GENUINE CUMMINS PART?

Yes—OE Cummins 3923129 (cross-ref Mopar 4882763).