Relays for Caterpillar E312C, E320C, E320B Excavators

Our company specializes in supplying a full range of relays for Caterpillar E312C, E320C, and E320B excavators. These relays are critical components in the excavator’s electronic control system, performing essential functions such as engine starting, preheating, timing, wiper control, heater control, and hydraulic solenoid valve actuation – all of which directly affect the machine’s starting performance and operational stability. Our product portfolio includes timer relays, starter relays, preheat relays, heater relays, wiper relays, and general‑purpose power relays.

Every model strictly adheres to original equipment manufacturer (OEM) specifications and has undergone rigorous electrical performance and reliability testing to ensure perfect compatibility with your equipment. We offer both genuine OEM parts and validated high‑quality alternative solutions. With ample stock on hand, we can respond quickly to your delivery requirements. In addition, our technical support team is available to assist you in verifying part numbers and confirming model compatibility, ensuring accurate selection every time. Choosing us means securing stable, long‑lasting electrical protection for your Caterpillar machinery.

Below are the common relay models, functions, and compatible machines for Caterpillar E312C, E320C, and E320B excavators.

Relays act as electrical "switches" in an excavator's system – they use a low‑current signal to control high‑current circuits, protecting the electronic control modules (ECMs). Many relays are interchangeable across these models.

**Common Relay Models and Functions**
Part Number	Type / Function	Applicable Models (E312C, E320C, E320B)	Remarks
104-3204: Timer Relay / Starter Relay	E320B, E320C	Controls engine starting circuit; common for 12V/24V systems
111-4870X: Starter Time Relay	E320B	Built‑in timing control to protect the starter motor; for 12V systems
125-1302: Heater Relay Switch	E320B, E320C	Controls heater circuits
163-6703 / 163-6703X: Time Relay	E312C, E320C	General‑purpose time relay
165-4026: Magnetic Relay Solenoid Valve	E312C, E320C	Used for precise hydraulic control; 12V/24V compatible
182-9403: Starter Relay	E312C	Controls current to engage the starter motor; for 12V systems
9X-8124: Preheat Relay	E320B, E320C	Used in engine pre‑heating systems
155-7042: Wiper Relay Controller	E320B, E320C	Controls cab wiper operation
161-3128: Safety Control Unit / Starter Relay	E312C	Specific to 312C and 318C models
SSA521A704A: General‑purpose Relay	E312C	24V, 10A, 4‑pin
082-5378: General‑purpose Relay	E320B	Used in power distribution centres