Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Alternator System Testing
Many different models of test equipment are available for testing the voltage and current output of the various alternators systems. Connect and operate the equipment in accordance with the manufacturers instructions.
If voltage or current output of the complete system is below specifications, by-pass the voltage regulator and test the alternator alone. If output is still below specifications, the alternator is at fault. If the output rises to specifications when the regulator is bypassed, the regulator is at fault.
On the common regulators several methods of bypassing can be used for testing. On regulators with plug-in connectors, remove the harness from the regulator and plug a jumper adapter into the harness plug.
On Chrysler Corp. vehicles with open terminal regulators, disconnect the ignition and field wires and connect them together with a jumper lead.
On 1968 Delco-Remy alternators with integral regulators, attach a jumper wire between the regulator heat sink and the alternator frame.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.