Tech Basics 1 Ford External Regulator Charging Systems COLUMN BY WESLEY GRUENINGER (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 vehicles use two similar charg- ing systems from 1963 until 1990. Although they both use the same parts, they are wired differently depending on whether they have a charge-light or only a charge-gauge. Figure I shows the components and how they are connect- ed for a charge-light system. Gauge- only systems will be discussed in the next section. Here’s a list of the compo- nents 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 diagnosing any charging problem. B Starter relay—isn’t part of the charging system, but serves as a connection 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 B+ stud and the volt- age regulator “A” terminal. This harness is a common problem area. The fusible link can be bad or it can be corroded away. The con- nection where the wire branches off to the “A” terminal of the volt- age regulator is also prone to cor- rosion. It’s not uncommon to find low voltage or no voltage at the “A” terminal. Opening the harness and repairing the connection is the fix here. E Ignition switch F Resistor—allows current to flow in case of bulb failure. Not used in vehicles without charge-light. G Indicator Light—bulb can fail. Not used in vehicles without charge-light. H Voltage regulator—must be properly grounded. Some vehicles have a ground wire from the alter- nator to a regulator mounting screw. If a ground wire isn’t there you should install one. Remember, these are older and usually rusty vehicles and you can’t count on body grounds being in good shape. Use dielectric grease on all connections. I Alternator—be sure to clean cor- rosion off the grounding areas where the alternator mounts. There are two styles of alternators—see Figure 2. On large case alternators with the “T” shaped plug it’s very common for the plug to corrode. On small case alternators that use the press-on connectors make sure they are clean and give them a little squeeze with a pliers to restore a tight fit. Use dielectric grease on all @9O000 Yellow/white G FIGURE 2 — Alternator styles and terminal positions ALTERNATOR STYLES Large case – terminals on side 70 Amp, 90 Amp, 100 Amp Small case – terminals on back 40 Amp to 65 Amp TERMINAL DESCRIPTION B+ Output to battery S % voltage output F Field current input G_ Ground