Tech Basics 3 Honda/Toyota 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.) Honda/Toyota—Internal Fan Alternators— Charging Diagnostics Nippondenso Internal Fan alternators have been used on Hondas and Toyotas since the mid-eighties. Although there are many different mounting and pulley configurations, these alternators are virtually the same inside. The round socket on the back of the alternator has three terminals. These are: S – sense: The voltage regulator uses the S terminal to sense the battery voltage. It always has power whether Key-On or Key-Off IG – ignition: The /G terminal goes on and off with the ignition switch. It is the power input for the alternator. The alternator will not charge without power to the /G terminal. L – light: This terminal has several functions. eIt turns on the charge-indicator light when the key is in the “run” position. It supplies a path to ground for the charge-indicator light, making the bulb glow. ¢ After starting the engine, on carbu- reted cars, the L terminal becomes an output. It supplies power to the electric choke and creates the same voltage on both sides of the charge- indicator light. No electricity can flow through the filament and the bulb goes out. ¢ After starting the engine on fuel- injected cars, the L terminal simply goes “open”. Since the path to Quick test procedure 1. If carbureted, unplug the electric choke. 2. Remove the plug from the alternator. 3. Turn ignition key to “run” position. (engine off) 4. Use a test-light to test all three terminals in the car’s harness plug. Not the terminals on the alternator! 5. Use chart in Figure 3 to troubleshoot. Od0d000 SWITCH FUSIBLE-LINKS May be: Fusible wire, Maxi Fuse, PAL Fuse CHOKE HEATER IGNITION HOH CHARGE LIGHT @ TOYOTA LATE MODEL PLUG Od0d000 IGNITION SWITCH FUSIBLE-LINKS May be: Fusible wire, Maxi Fuse, PAL Fuse CHOKE HEATER © CHARGE LIGHT = = 4 PRONG PLUG (see text) Figure 2—Typical Honda Charging System ground is gone the charge-indicator light turns off. Honda Variations Honda has several variations of this charging system. °3 terminals 7 terminal — Some Civics have only JG and L terminals. The third is a D (dummy) terminal and is not connected to anything. Use the Quick Test Procedure to test only the JG and L.