Electrical Goes Dead

Step by step repair guide on how to fix an automotive electrical system that goes dead when the engine is cranked over. This article pertains to all vehicles.

Difficulty Scale: 3 of 10

Tools and Supplies Needed

  • Flashlight
  • Wire brush or battery cable and terminal cleaner
  • Protective eye wear and gloves

Step 1 - For electrical energy to flow all electrical connections must be secure and free from corrosion, this is especially true for high amperage draws such as an engine starter. When currant demands are low such as interior lights the circuit will work just fine, but when the ignition key is turned engaging the starter, the circuit shuts down due to heat, and then reconnects once cooled. This condition is common for the positive terminal and cable of the battery. Neutralize battery acid using baking soda and rinsing with water before work begins.  (Note: Record radio stations for re-entry once the battery is replaced. Neutralize any battery acid by sprinkling baking soda over the top and around the battery base, rinse with fresh water to remove any lingering acids.) (CAUTION: Never connect positive and negative terminals with a conductive object such as a wrench. Also, never connect the positive battery terminal to any body, chassis or engine parts.)

Battery Terminal Corrosion
Step 2
- Once the terminal and battery cable have been cleaned, use a small socket or wrench to loosen the cable end (key OFF.)

Loosen Battery Cable
Step 3 - After the battery cable end has been loosened, grasp the cable and twist to remove.

Battery Cable Removed
Step 4
- Next, using a wire brush or battery terminal and cable cleaner remove all corrosion by resurfacing both connection areas.

Clean Terminal and Cable End
Step 5 - Once the battery terminal and cable end have been cleaned reinstall the cable and tighten.

Tighten Battery Cable
Step 6
- After the repair is complete, recheck the problem and reinstall the terminal cover.

Reinstall Terminal Cover
Once the job is complete retest the system, many other battery issues can emerge such as dead battery over night, alternator charging or jump start problems. Once the engine is running check charging system to ensure proper operation.

Helpful Information

When an engine is cranked over it demands a high amount of amperage from the battery.  As the electrical demand is increased heat will develop inside the wire or connection. This heat will disconnect (short circuit) the electrical flow until the connection cools. Since the battery provides the main electrical power to the remainder of the vehicle (lights, dash, interior) all electricity is shut off.  Once the connection cools it can reconnect starting the process all over again.

The battery cable connection must be clean (free from corrosion) and tightly fastened to the terminal to allow the flow of electricity from the battery to the starter. Battery cable connections must be tight and not wiggle on the battery terminal. If the cable is loose remove it to clean, then re-tighten the cable with a wrench or socket wrench.

When a battery short circuits internally, it can cause a loss of power, and then regain the power a short time later. Inspect the battery of bulging it could have a warped plate that can short under certain conditions. This problem is rare but it does happen.

Note: Never crank an engine over when anyone is near the battery or engine. A battery is filled with explosive gasses that can ignite when extreme heat or a spark is present. A battery could have residual acid on the outside casing so use caution when handling a battery and the surrounding area. Use baking soda to neutralize any suspected acid residue before work begins.

Article first published