3412E Petroleum Engine Electrical System Caterpillar

Electrical System
1.1. Grounding Practices
2.1. Engine Electrical System

------ WARNING! ------

The connection of battery cables to a battery and the disconnection of battery cables from a battery may cause an explosion which may result in injury or death. The connection and the disconnection of other electrical equipment may also cause an explosion which may result in injury or death. The procedures for the connection and the disconnection of battery cables and other electrical equipment should only be performed in a nonexplosive atmosphere.


Grounding Practices

Proper grounding for the auxiliary electrical system and engine electrical systems is necessary for proper performance and reliability. Improper grounding will result in uncontrolled electrical circuit paths and unreliable electrical circuit paths.

Uncontrolled engine electrical circuit paths can result in damage to main bearings, crankshaft bearing journal surfaces, and aluminum components.

To ensure proper functioning of the equipment and engine electrical systems, an engine-to-frame ground strap with a direct path to the negative battery post must be used. This may be provided by way of a starting motor ground, a frame to starting motor ground, or a direct frame to engine ground.

An engine-to-frame ground strap must be used in order to connect the grounding stud of the engine to the frame of the frame and to the negative battery post.

The engine must have a wire ground to the battery.

Ground wires or ground straps should be combined at ground studs that are only for ground use. All of the grounds should be tight and free of corrosion.

All of the ground paths must be capable of carrying any likely current faults. An AWG #0 or larger wire is recommended for the grounding strap to the cylinder head.


When boost starting an engine, the instructions in Systems Operation, "Engine Starting" should be followed in order to properly start the engine.

This engine may be equipped with a 12 volt starting system or a 24 volt starting system. Only equal voltage for boost starting should be used. The use of a higher voltage will damage the electrical system.

The Electronic Control Module (ECM) must be disconnected at the "J1/P1" and "J2/P2" locations before welding on or near the engine.

The engine alternator should have a battery ground with a wire size that is capable of managing the full charging current of the alternator.

The engine has several input components which are electronic. These components require an operating voltage.

Unlike many electronic systems of the past, this engine is tolerant to common external sources of electrical noise. Buzzers that use electrical energy can cause disruptions in the power supply. If buzzers are used anywhere on the machine, the engine electronics should be powered directly from the battery system through a dedicated relay. The engine electronics should not be powered through a common power bus with any other keyswitch power.

Engine Electrical System

The electrical system has the following separate circuits:

  • Charging

  • Starting

  • Accessories with low amperage

Some of the electrical system components are used in more than one circuit. The following components are common in more than one circuit:

  • Battery or batteries

  • Circuit breakers

  • Battery cables

  • Ammeter

The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order to keep the battery at full charge.

The starting circuit is activated only when the start switch is activated.

The accessory circuit with the low amperage and the charging circuit are connected through the ammeter. The starting circuit is not connected through the ammeter.

Information System:

C11 and C13 Engines for Caterpillar Built Machines Fuel System - Prime
C11 and C13 Engines for Caterpillar Built Machines Cooling System
345D, 349D and 349D2 Excavators Hydraulic System Relief Valve (Main) - Test and Adjust - Heavy Lift
3412E Petroleum Engine Electronic Control System Components
3508B, 3512B and 3516B Generator Set Engines Camshaft - Install
3512B and 3516B Engines Camshaft - Remove
C-10 Petroleum Engine Fuel System Pressure - Test
349F and 352F Excavators Machine System Specifications Bucket Linkage - VB Family
C-10 Petroleum Engine Cooling System - Test
C-10 Petroleum Engine Cooling System - Check - Overheating
325D and 329D Excavators Hydraulic System Oil Filter (Return) - Replace
C-10 Petroleum Engine Inlet Manifold Pressure - Test
120M, 12M, 140M, 140, 150, 160M and 160 Motor Graders Power Train
3412E Petroleum Engine Battery - Test
C27 PET GEN SET Electric Power Generation and C27 KNOCKDOWN K Petroleum Power Train Package Fuel Related Components in Cold Weather
C32 Marine and Marine Generator Set Engines Air Inlet and Exhaust System
C0.5, C0.7, C0.7, C1.1/3011C, C1.5/3013C, C1.6 and C2.2/3024C/3024CT Industrial Engines and Engines for Caterpillar Built Machines Refill Capacities and Recommendations
C32 Marine and Marine Generator Set Engines Cooling System
325D and 329D Excavators Engine Starting with Auxiliary Start Receptacle - If Equipped
SR4 and SR4B Generators and Control Panels Maintenance Interval Schedule - Standard
SR4 and SR4B Generators and Control Panels Maintenance Interval Schedule - Standby
2004/11/01 New Injectors and New Flash Files are Now in Production {1290, 7620}
345C Excavator Hydraulic System Stick Drift Reduction Valve
C7 Engines for Caterpillar Built Machines Fuel Transfer Pump - Remove