Operation and maintenance manual

QSB4.5 and QSB6.7 Alternator

Section A - Adjustment, Repair, and Replacement Page A-1

Alternator

General Information

Due to the number of different alternator brands and configurations, the following procedure has been generalized to

cover the most common configurations. Consult the alternator manufacturer for any information that is not covered in

this procedure.

Typical Delco™ Alternator Wiring System

Indicator (I) Terminal

The main function of the indicator (I) terminal is to indicate if the alternator is working correctly. Typically, an indicator

light is wired to this terminal. If the alternator is not charging properly, the light turns on. Another function of the

indicator (I) terminal is that it can be used to supply up to 1 ampere of output at system voltage.

Lamp (L) Terminal

Similar to the I terminal, the L terminal is used to indicate if the alternator is working correctly. The difference between

the L terminal and the I terminal is that the L terminal is a current sink only and can not be used to reduce turn on

speed.

Relay (R) Terminal

The function of the relay (R) terminal varies. It can supply up to 4 amperes of output at one-half nominal alternator

voltage to power items such as a tachometer or an hour meter.

One-Wire System

This is the simplest of the wiring systems because the only wires connected to the alternator are at the battery (BAT)

and ground terminals. (See the illustrations below.) Connecting to the R terminal, L terminal, and I terminal is optional.

Three-Wire System

This system requires more wiring because it has a battery (BAT) terminal, R terminal, two blade terminals identified as

number 1 and number 2, and a ground terminal. Typically, in the three-wire system, the number 1 blade terminal

serves as the I terminal. (See the illustrations below.) The advantage of the three-wire system is that it provides the

same features as the one-wire system, plus remote sense. By connecting the number 2 blade terminal to the battery's

positive (+) terminal, the voltage is both sensed and regulated at the battery, instead of at the alternator. This

eliminates the potential for voltage losses in the wiring from the alternator to the battery.

One Wire System, Typical Alternator (Delco-Remy™) with Combined Metri-Pack™ Connector

1 GRD* Ground

4 R* Charge indicator, automatic lockout

system, tachometer**

5 BAT Battery

7 L Lamp Terminal

*Not all alternators have this feature.

**Provides voltage pulses at about one-half system voltage at a frequency of one-tenth of alternator rpm.