Alternator & Regulator Test

1. First make sure you have a good battery, and alternator belt is tight and in good condition. Also make sure connections at alternator and main fuses are good. Next, check No. 2 (15 A) fuse in dash fuse box and No. 18 (20 A) fuse in main fuse box. (If blown, charge system light will come on even if system's working properly.)
2. Disconnect 4-P connector from alternator. With ignition switch on, there should be battery voltage between IG (BLK/YEL) terminal and body ground, and between S (YEL/BLU) terminal and body ground. See Fig 1 .
3. If there is battery voltage, go to next step. If there is no voltage, check for blown No. 2 (15 A) fuse in dash fuse box or No. 18 (20 A) fuse in main fuse box and/or an open in BLK/YEL wire between dash fuse box and voltage regulator, or YEL/BLU wire between main fuse box and voltage regulator.
   NOTE: Test use SUN VAT-40 (or equivalent). See Fig 2 .
   Fig 1: Identifying Alternator 4-P Connector

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   Fig 2: Identifying SUN VAT-40 Tester Components

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4. Following the illustrations instructions, connect SUN VAT-40 (or equivalent) and turn test selector switch to No. 1 position. See Fig 2 .
5. Attach positive tester cable and voltmeter positive lead to jump start terminal at main fuse box. See Fig 3 .
6. Attach negative tester cable and voltmeter negative lead to top of throttle body. See Fig 4 .
NOTE: The arrow points in opposite direction from alternator B terminal.
7. Attach inductive pick-up to B terminal at alternator. See Fig 5 and Fig 6 .
8. Start engine. Turn off all accessories, move selector switch to No. 2 position.
9. Raise engine speed to 2,000 RPM and hold (make sure cooling fans are off). Apply a "load" with carbon pile, so voltage drops to no less than 12 volts. Check maximum amperage reading and compare with chart. See Fig 7 . If amperage is "NORMAL" system is okay. Proceed to CHARGE SYSTEM LIGHT TEST  . If amperage is "ABNORMAL" go to next step.
   Fig 3: Connecting Positive Tester Cable & Voltmeter Positive Lead

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   Fig 4: Connecting Negative Tester Cable & Voltmeter Negative Lead

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   Fig 5: Connecting Inductive Pick-Up

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   Fig 6: Identifying Inductive Pick-Up Connection Direction

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   Fig 7: Output Current Vs. Engine Speed Chart

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10. Stop engine. Perform full field test by inserting full field tester lead into full field access hole at back of alternator. See Fig 8 .
11. Move test selector switch to No. 1 position.
12. Start engine and raise engine speed to 2,000 RPM and hold (make sure cooling fans are off).
CAUTION: The voltage will rise quickly when alternator is full fielded. Do not allow voltage to exceed 18 volts or damage to electrical system may result.
NOTE:
13. Switch field selector to "A (Ground)" position momentarily and check amperage reading. As an alternative, use a screwdriver and an ammeter to full field alternator. See Fig 9 . If amperage is within specification, replace regulator. If amperage is not within specification, replace alternator.

Fig 8: Performing Full Field Test

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Fig 9: Full Field Test Using Screwdriver

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