The 3L6306 (3L-6306) Caterpillar (CAT) Oil Pressure Switch monitors engine oil pressure and triggers a low-pressure alarm; it serves as a standard protective component for classic, older-model CAT equipment. I. Core Specifications (OEM Standard)

Table

Parameter Item | Detailed Specification

Part Type | Mechanical Oil Pressure Switch (Normally Open / Normally Closed)

Trigger Pressure | 55 kPa (8 psi) [Closes to trigger alarm]

Reset Pressure | 40 kPa (5.8 psi) [Opens to reset]

Electrical Interface | Screw Terminal

Mounting Thread | 1/4"-18 NPTF (American Dryseal Taper Pipe Thread)

Rated Current | 15A (Resistive Load)

Operating Voltage | Compatible with 12V/24V Systems

Operating Temperature | -40°C to 125°C

Protection Rating | IP65 (Dustproof and Splash-resistant)

Weight | Approx. 0.09 kg (0.20 lbs)

II. Applicable Models (Classic/Older Series)

Engines: 3306, 3306B, D320A, D330A, D333A

Articulated Trucks: D250B, D25C, D300B, D30C, D350C, D35C

Motor Graders: 12G, 14G, 140G, 16G

Track-Type Loaders: 977K, 983

Track-Type Tractors (Dozers): D9G, D9H

Scrapers: 627, 627B, 637, 637B, 637D, 639D, 657, 657B, 666, 666B

Off-Highway Trucks (Mining Trucks): 768C, 769C, 772B, 773B, 777, 777B, 784B, 785, 785B, 789, 789B, 793B

III. Replacements and Interchangeability

Direct OEM Interchange: CA3L6306

V. Fault Diagnosis and Self-Testing Alarm Light Constantly On: Oil pressure is normal, yet the alarm is active; this is typically caused by stuck internal contacts or a short circuit within the switch.

Alarm Light Off: Oil pressure is too low, yet no alarm is triggered; this is typically caused by an open circuit in the switch contacts or a sensor failure.

Self-Diagnostic Procedure:

Disconnect the connector plug and use a multimeter to measure the resistance across the switch terminals: the circuit should be closed (conductive) when the pressure is <55 kPa, and open (non-conductive) when the pressure is >40 kPa.

Inspect the terminals for signs of oxidation or looseness, and check the wiring harness for any damage.