Cummins 3935888 — Genuine Starter Motor for 5.9L B-Series/ISB

MPN: 3935888  |  Also Known As: starter, starting motor, OSGR starter  |  Cross-Refs (ID only): Cummins 3921682; Mopar 4741012, 4746639; Denso 228000-2292; Lester 17548

Genuine Cummins starter motor designed for reliable cold-cranking performance and long service life on B-Series 5.9L engines. Direct-fit OE replacement for 2nd-Gen Ram trucks; includes gear-reduction OSGR design for strong torque and efficient starts.

Features & Benefits

• OE-calibrated torque & engagement for fast, consistent starts.
• Gear-reduction (OSGR) architecture for high cranking power with lower current draw.
• Direct-fit replacement for 5.9L applications with factory connectors and mounting.
• Durable internals engineered for heavy-duty duty cycles and repeated heat soak.
• Backed by Cummins quality for fit, function, and longevity.

Verified Fitment (Automotive)

Industrial/Off-Highway: B3.9/B5.9 family (BS3 era). Verify by ESN before ordering.

Specifications

• Type: OSGR gear-reduction starter
• Voltage: 12V
• Power: ~2.7 kW
• Rotation: CW
• Tooth Count: 13-tooth pinion
• Mounting: 3-bolt pattern (Denso style)
• OE Part Number: 3935888 (alt. Cummins 3921682)
• Common Cross-Refs: Mopar 4741012 / 4746639; Denso 228000-2292; Lester 17548

Often Paired With

• Starter bolt kit: year-correct hardware to prevent loosening under vibration.
• Battery & cable refresh: Group 65 AGM batteries and upgraded ground/positive cables for best cranking voltage.
• Starter relay/solenoid circuit check: inspect/replace worn relays and corroded connectors.

What’s In The Box

• (1) Genuine Cummins Starter Motor (3935888)
• Mounting hardware not included (reuse or source correct bolts).

Installation Tips

• Load-test both batteries; clean and tighten all grounds and power lugs before install.
• Verify ring-gear condition and proper pinion engagement; replace worn parts as needed.
• Torque mounting fasteners to factory spec; recheck after initial heat cycles.
• Check starter relay and ignition switch circuits for voltage drop.

FAQ

WILL THIS FIT MY 1994–2002 5.9L CUMMINS RAM?

Yes—this OE-type starter is used on 1994–2002 5.9L (12V and 24V VP44) Ram 2500/3500. Always confirm by VIN/ESN.

IS THIS THE DENSO-STYLE GEAR-REDUCTION STARTER?

Yes—it’s the OSGR design (12V, ~2.7 kW, 13-tooth) commonly referenced as Denso 228000-2292 in cross-lists.

WHAT ARE COMMON CROSS-REFERENCE NUMBERS?

Cummins 3921682; Mopar 4741012/4746639; Denso 228000-2292; Lester 17548 (ID reference only).

DO I NEED NEW BOLTS OR A RELAY?

Hardware and relays are separate. We recommend new bolts and a quick relay/voltage-drop check during replacement.

WILL THIS WORK ON 2003+ COMMON-RAIL TRUCKS?

Those models typically use a different starter part number—confirm your VIN/ESN for correct fit.