On-Vehicle Output Test

1987 Chevrolet Suburban 1/2 Ton 2WD V8-379 6.2L DSLSECTION On-Vehicle Output Test

1. Connect ammeter in series at alternator output BAT terminal, then connect voltmeter and carbon pile across battery terminal. Ensure battery is fully charged.
2. Operate engine at moderate speed. With carbon pile turned Off, check voltage across battery terminals.
3. If voltmeter reads above 16 volts, repair (CS-144) only or replace alternator.
4. If voltmeter reads below 16 volts, proceed as follows:
a. With engine still running at moderate speed turn accessories On and load battery with carbon pile to obtain maximum amperage output. Maintain voltage above 13 volts.
b. If output is within 15 amps of rated output, alternator is satisfactory.
c. If output is not within 15 amps of rated output, alternator is defective and requires repair (CS-144 only) or replace alternator.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.