I. Core Parameters and Specifications

Manufacturer Part Number: 318-1181 (3181181, CA3181181)

Replacement Models: 6V-2455, 189-5746

Official Name: Revolution Speed Sensor / Crankshaft Speed Sensor

Type: Magnetic-Electric (Passive); requires no external power supply and generates pulse signals via changes in magnetic flux.

Core Applications:

Monitors engine crankshaft / flywheel speed (RPM).

Provides crankshaft position signals to control fuel injection and ignition timing.

Used for engine overspeed protection, idle speed control, and fault diagnostics.

Electrical Characteristics:

3-pin waterproof connector (Signal +, Signal -, Shield / Ground).

Output: Sine wave / Square wave pulses (passive magnetic-electric signal).

Operating Voltage: Passive (requires no external power supply); compatible with 12V/24V systems.

Mechanical Parameters:

Thread: 5/8"-18 UNF (Standard engine sensor interface).

Thread Length: 59.5 mm (2.34 in).

Total Length: 82.68 mm (3.26 in).

Wire Length: 150 mm (5.91 in).

Material: Stainless steel housing; IP67 protection rating.

Operating Temperature: -40°C to 125°C.

Measurement Range: 0 – 8000 RPM (Covers the full operating speed range of heavy-duty Cat engines).

Accuracy: ±1 RPM (High-resolution pulse output).

II. Compatible Engines (Most Comprehensive List)

Diesel Engines (Mainstream Models)

3126B, 3406C, 3408, 3408B/C, 3412, 3412C

3508, 3508C, 3512, 3512B/C, 3516, 3516B/C/E C12, C15, C18, 3606, 3608, 3612, 3616

Gas Engines (G Series)

G3406, G3412, G3508, G3512, G3516, G3520C/E

III. Compatible Equipment (Full Model Coverage)

Excavators (Most Common)

312C, 315C, 320B/C, 322B/C, 325B/C, 330B/C, 336D, 365B, 375L

312D2, 320D2, 329D, M325D

Mining Trucks / Construction Vehicles

773B, 777B, 785C, 789C, 793D

Articulated Trucks: 725C, 730, 735, 740, D400E II

Other Equipment

Dozers: D8N, D9N, D10N

  Loaders: 966G, 980G, 988G

Pavers: AP-1000B, AP-1055B, BG-240C/260C

Telehandlers: TH220B–TH580B (Full Series)

IV. Fault Symptoms and Diagnosis

Typical Symptoms

Engine fails to start / Difficult starting (No speed signal; ECM does not inject fuel)

Unstable idle, poor acceleration, significant RPM fluctuations

ECM reports fault codes: P0335 (Crankshaft Position Sensor Fault), P0336 (Abnormal Speed Signal)

Engine stalls while driving, loss of power (Loss of speed signal)

Sensor coil short circuit / open circuit, dirty magnetic tip, excessive air gap

Quick Check

Resistance Test: Measure the **Signal +** and **Signal -** pins on the 3-pin connector Internal Resistance: Normal range 800–1500 Ω (typical value for magnetic coils).

AC Voltage Test: Measure the signal output during startup; a pulsed AC voltage of 0.5–5 V should be present.

Gap Inspection: The clearance between the sensor and the flywheel ring gear should be 0.8–1.5 mm; an excessive gap will result in a weak signal.

Substitution Test: Replace the unit with a 6V-2455 or 189-5746 to verify whether the fault is resolved.

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