Quote:
Originally Posted by 6T9GTO
I can remove the battery NEG cable and the motor shuts off.
Should I try a new regulator? The one on there looks pretty new, but I don't remeber when I put it on.
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Disconnecting the battery with the engine running is an EXCELLENT way to fry the diodes in the alternator. Disconnecting the cable creates a momentary voltage surge way above what the diodes are comfortable with.
DO NOT "try" a new regulator. Test first, replace parts second.
1. What is battery voltage with everything shut off. This is called "Open-Circuit" Voltage (OCV)--and it better be 12.6--12.7 or so. If low, charge battery.
2. What is charging voltage at the ALTERNATOR output terminal, fast-idle (1200--1700 rpm) Should be 13.5--15 volts. 14.2--14.5 preferred.
3. What is charging voltage at the BATTERY + terminal--same idle speed? Better be VERY close to voltage at the alternator. If not, wire harness has problems.
4. Engine off, disconnect 4-wire connector at regulator. Install jumper between #3 and "F" (#1) on the CONNECTOR, not the regulator itself. Start engine, check charging voltage. Should be 16+ volts, alternator will whine. Don't run engine more than needed to check voltage, alternator will get HOT. This is called "Full-Fielding" the alternator. The alternator will produce it's MAXIMUM power at that RPM.
If it doesn't charge when full-fielded, you've got a defective alternator or a defective wire harness. Check continuity from "F" at the harness connector to the wire of the same color at the two-wire plug on the alternator. Check continuity of the other wire in the two-wire plug on the alternator to #2 on the connector at the regulator.
If it charges when full-fielded, and didn't before--regulator is defective.
I STRONGLY suggest that if you find a defective alternator or defective regulator, that you install a newer 10- or 12-SI internally-regulated alternator instead. They put out way more power at idle and low engine speed than the older alternators; and they're inexpensive. You will need an alternator pigtail (about $6, maybe less) and two home-made jumper wires about three inches long.
I would not spend ten dollars to fix an old external-regulator charging system with original-style parts when the upgrade is so simple and cost-effective.
