For 1990-2009 cars

# GENERAL INFO. ON CS SERIES GENERATOR WIRING

1987-89 ALL MODELS WITH CS SERIES GENERATORS

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

This terminal is used for one of two purposes, depending on the model. First, on most models, the F/I terminal is the "field" terminal. It is used to turn on the generator thru 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 can also be used to turn on the generator. It is connected to the generator thru the resistance of the lamp or a resistor.

#### Important: If this terminal is connected directly to either an ignition feed or a battery feed, without going thru 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 F Car Service Manual is incorrect. It shows both the "F/I" and "L" terminals connected, when only the "F/I" terminal is actually connected. The 1989 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.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.