Generator - Terminal Descriptions & Revised Wiring
89chevy31Number: 89-224-8A
Section: 8A
Date: July 1989
Subject: GENERATOR WIRING
Model and Year: 1987-89 ALL PASSENGER CARS AND TRUCKS WITH CS SERIES GENERATORS
TO: ALL CHEVROLET DEALERS
The new CS series generators (CS121, 130 and 144) have slightly different requirements for turning on the generator than the older SI models. The terminals in the four-way connector are used as follows:
"S" Terminal
This is the "sense" terminal. It is connected directly to a battery positive lead. It provides the generator with a battery reference voltage so that the regulator can determine the level of charging needed. Some vehicles do not have this lead connected because the generator also has an internal sense function which will operate if the lead is cut or broken.
"F/I" Terminal
The F/I terminal is the "field" terminal and is used to turn on the generator through an internal resistor. It is used on cars with gage clusters and is connected directly to an ignition feed (no external resistance is needed).
"L" Terminal
This is the "lamp" terminal. It is used to operate the I.P. telltale warning lamp, and also to turn on the generator. It is connected to the generator through the resistance of the lamp or a resistor. General Information on Generator Wiring - Page 2
Important: If this terminal is connected directly to either an ignition feed or a battery feed, without going through a resistor or a bulb, the regulator will eventually be destroyed.
Note 1: Some vehicles may have wires to both the "F/I" and 'L" terminals. Either
terminal will turn on the generator. In addition, some vehicles may have wires to both terminals, but only one will be connected on the other side of the bulkhead connector. This is done to commonize engine harnesses. Again, either wire will turn on the generator, and no power to one of the wires should not be considered a problem with the vehicle.
Note 2: The 1988 Camaro Car Service Manual is incorrect. It show's both the "F/
I" and "L" terminals connected, when only the "F/I" terminal is actually connected. The 1989 Camaro Service Manual is correct for both 1988 and 1989.
"P" Terminal
This terminal is not currently used on any application. It can be used to supply an engine speed output signal for a tachometer on diesel engines.