Power and Grounding Considerations 4.2.2 ECU Battery (-) Connections The ECU requires four battery (-) connections to battery (-). These four ECU battery (-) input connections are made through pins J1- 61, 63, 65, and 69. All four of these pins should be connected directly to the negative terminal on the battery, not to the engine ground stud or any other ground location. These connections should be #14 AWG GXL wire. NOTE: For already installed Tier 3 and earlier applications, four un-switched positive battery connections and four ground connections are recommended but not required.
New installations, especially those with HEUI fuel systems, should be designed with all four un-switched positive battery connections. 4.2.3 Engine Ground Stud to Vehicle Battery Ground To ensure proper functioning of the vehicle and engine electrical systems, there must be a direct wire path from the engine ground stud to the battery negative post. A maximum of three ring terminals are to be connected to the engine ground stud to ensure ground connection integrity. More than three terminals can cause the stud to loosen too easily. Caterpillar recommends splicing like-size wires together as a method of reducing ring terminal congestion at the ground stud.
A connection routed to a main frame ground can also be made if the following guidelines are followed: 1.Connections to the frame must not be made with star washers. Star washers should not be counted on to remove paint from painted surfaces. Use flat washers for this connection, with the paint completely removed in this area. 2.Any paint must be completely removed from the frame rail at the point where the connection is made. Failure to do so reduces the effectiveness of the connection. 3.The ground path is not made through frame cross members. Bolted connections of frame cross members may not always provide required continuity for this critical connection.
4.Conductive grease or other methods used to reduce/eliminate the effect of corrosion on the frame rail connection. Caterpillar does not recommend a connection from the engine ground stud to the main frame rail at a connection point different than where the battery ground connection is made. A two-point frame rail connection method depends on frame rail connections. Manufacturing process control of frame rail connections is difficult to control. This multiple frame rail connection scheme is also more difficult to troubleshoot. 4.3 Air Starter Equipped Vehicles Refer to the guidelines for connection to the main frame ground in Engine Ground Stud to Vehicle Battery Ground (section 4.2.3).
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