266-1478 (2661478) Caterpillar Rotary Throttle / Position Sensor (TPS). Compatible with heavy-duty Caterpillar equipment—including large wheel loaders, road rollers, pavers, and other construction machinery—this sensor detects the angle of the throttle actuator and outputs a PWM signal. I. Core Parameters and Specifications

OE Model: 266-1478 / 2661478 (Caterpillar Original Part Number)

Type: Rotary Position Sensor (Throttle Position Sensor / TPS)

Function: Detects the rotational angle of the throttle actuator and outputs a PWM signal to the ECM to control fuel injection volume and power output.

Electrical Interface: 3-pin waterproof connector (Standard Caterpillar heavy equipment interface)

Rotational Range: Approx. 72° (Same specifications as 266-1467)

Output Signal: PWM (Pulse Width Modulation)

Structure: Non-contact sensing (Shaftless design; highly durable)

Compatible Systems: Caterpillar Electronic Fuel Injection (EFI) Engine Control Systems (3126, 3406, C9, etc.)

II. Compatible Engines and Equipment Models (High-Frequency)

1. Compatible Engines

3054, 3116, 3126, 3176C, 3196, 3306, 3406, 3408, 3412, 3456, 3508, 3516

2. Compatible Equipment (Mainstream)

Wheel Loaders: 938G II, 950G II, 962G II, 966G II, 972G II, 980G II, 980H, 988G, 988H, 990H, 992G, 994F

Compactors: 814F, 815F, 816F, 824H, 825H, 826H, 834G, 836H, 844H

Pavers / Cold Planers: AP-1000B, AP-1055B, PM-201, PM-565

Motor Graders: 12K, 120K, 140K, 160K

III. Alternative Models and Suppliers

Table

Type Alternative Model Description

Original Part Number Match 2661478 Genuine Cat Part — Fully Interchangeable

V. Symptoms and Troubleshooting

Common Faults:

Unstable engine idle, lack of acceleration power, poor throttle response

Throttle actuator sticking or unresponsive

Fault Codes: P0122 / P0123 (Throttle Position Sensor Circuit Fault)

Troubleshooting Steps:

Check the 3-pin connector for looseness, corrosion, or water intrusion

Measure Power Supply: A 5V reference voltage should be present

Measure Signal: The PWM signal should vary linearly as the throttle is operated

Signal Abnormal → Replace Sensor; Signal Normal → Check Wiring or ECM