SUPPORT ASSEM. (R.H.) 3P1397 - Caterpillar

Illustration 1. Typical 24V starting circuit without a start relay.For Illustration 1 circuits, add a 3T2171 Relay Assembly and a 9F3099 Switch (Start Relay). See Illustration 3.
Illustration 2. Typical 24V starting circuit with a start relay.For Illustration 2 circuits that already contain the 9F3099 Switch or equivalent, add only a 3T2171 Relay Assembly. See Illustration 3.
Illustration 3. Typical 24V starting circuit with both the relay assembly and switch (start relay) added.With the correct modification, when the engine starts, the alternator (R) terminal causes the 3T2171 Relay Assembly to pull in and inhibit the 9F3099 Switch. This prevents actuation of the starter.