Tech Basics 4 Ford 2G (IAR) Charging Systems (Editors Note: Many thanks to Wes Grueninger, a 28-year industry veteran, for sharing this series of technical articles he’s cre- ated as a way to protect his sanity and save time han- dling customers with elec- trical problems. “I’d rather hand a tech bulletin to a customer with a prob- lem than have to explain for the 9 millionth time in my rebuilding career how to test an electrical system.’ Well said, Wes. We hope this series will indeed protect the sanity of many of our readers. Look for more Tech Basics in upcoming issues of the Exchange.) Ford introduced the 2G alternator in 1984. The voltage regulator is attached to the rear housing. There are two dif- ferent wiring schemes used, which depend on whether the vehicle has a charge-light or only a charge-gauge. Figure I shows the components and wiring for a charge-light system. Gauge-only systems will be discussed in the next section. Here’s a list of the components as shown in Figure I and some common problems. You should read this list and familiarize yourself with the parts no matter which system you are troubleshooting. A Battery—should be fully charged and load tested before diag- nosing any charging problem B Starter relay— isn’t part of the charging system, but serves as a con- nection point for the fusible link and the positive battery cable. C Charging system fuse —located in the fuse box. It may also protect other dash warning lights and gauges. D Fusible link— protects the wire to the alternator BAT terminals and the voltage regulator A terminal. This har- ness is a common problem area. The fusible link can be bad or it can be cor- roded away. The connection where the wire branches off to the A terminal of the voltage regulator is also prone to corrosion which can cause low voltage or no voltage at the A terminal. Opening the harness and repairing the connection is the fix here. E Ignition switch Figure 1—Components of a typical 2G charging system with a charge-light KOEO current flow – Regulator grounds the “I” terminal – Regulator uses current from “A” terminal to energize the rotor “ White/black @®00000 Black/orange Figure 2—Charge-light system KOEO (key on, engine off) KOEO current flow – Alternator “STA” terminal produces « voltage output to electric choke heater and regulator “S” terminal. terminal and charge-light goes out. – Alternator-produced current flows from “BAT” terminals “ – Regulator opens to the battery. – Regulator controls alternator output. @®800080 F Resistor — allows current to flow in case of bulb failure. Not used in gauge-only vehicles. G Indicator Light— bulb can fail. Not used in gauge-only vehicles. H Voltage regulator and plug— Use dielectric grease on all connections. I Alternator—be sure to clean corrosion off the grounding areas where the alternator mounts. J Rectifier Plug—see section titled “Changing the Rectifier Plug”. K Electric choke—always check the routing of the choke wire. It’s common to find it melted to the exhaust manifold or snagged under a valve cover from the last valve cover gasket change. Charge-Light System— How it Works The system with a charge-light has two stages of operation. The first stage is KOEO (Key on, Engine off) During KOEO current flows from the battery © through the fuse ™ through the ignition switch © through the charge-light/resistor ™ to the volt- age regulator I terminal. What’s the resistor for? It’s there as a backup for the charge-light bulb. If the filament in the bulb breaks, current will bypass the bulb and still get to the I terminal on the voltage regulator. Without the resistor, a blown charge-light bulb could disable the charging system! As soon as the voltage regulator “sees” current at the I terminal, it directs current from the A terminal to the rotor which causes it to become an