203-6749 (2036749) — 24V Compact Electromagnetic Relay / General Purpose Control Relay (Relay GP). Commonly used to control low-to-medium current circuits such as fans, windshield wipers, lights, glow plugs, and solenoid valves. I. Core Specifications

Part Number: 203-6749 (CAT OEM: 2036749)

Type: General-purpose Electromagnetic Control Relay (Non-starter, medium-current type)

Coil Voltage: 24V DC (Standard for heavy machinery)

Contact Current: Approx. 20–30A (Medium load)

Pins: 4-pin / 5-pin (Common configuration: 4-pin; 2 coil terminals + 2 normally open contacts)

Housing: Square black casing with mounting tab; standard blade-terminal style

Function: Uses a low-current signal to control the switching (ON/OFF) of medium-power circuits (fans, wipers, lights, pre-heaters, solenoid valves)

II. Applicable Models (Common)

Excavators: 320C / 320D / 323D / 325D / 330C / 336D / 345D

Wheel Loaders: 950H / 962H / 966H

Engines: C6.4 / C7 / C9 / C9.3

Dozers / Motor Graders: D6N / 12M, 140M, etc.

III. Distinction from High-Current Relays (175-2306)

203-6749 (Control Relay)

Current: 20–30A

Applications: Fans, wipers, lights, pre-heaters, solenoid valves

Size: Compact; 4/5-pin blade terminals

175-2306 (Starter Relay)

Current: 80–100A

Applications: Starter motors, main power supply

Size: Large; round metal housing with heavy-duty screw terminals

V. Common Faults

Symptoms: Corresponding component fails to operate (fan does not spin, wipers do not move, lights do not turn on)

Diagnostics:

Measure the voltage across the coil terminals to verify a normal 24V supply

Listen for the audible "click" (engagement sound) when power is applied

Test contact continuity (contacts should conduct current when energized)