Product Description
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)
| Year Range | Engine | Chassis |
|---|---|---|
| 1994–1998 | 5.9L 12-Valve (6BT) | Ram 2500/3500 |
| 1998.5–2002 | 5.9L 24-Valve ISB (VP44) | Ram 2500/3500 |
Industrial/Off-Highway: B3.9/B5.9 family (BS3 era). Verify by ESN before ordering.
Compatibility Notes:
- Built around the Denso-style OSGR 13-tooth, 12V, ~2.7 kW layout used on B-Series engines.
- For 2003+ common-rail applications, confirm the correct later starter P/N 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.
