Total Power Loss When Engaging Starter After Engine Wash - Corroded Ground Connections

Electricalbeginner✓ OP Confirmed

Problem

After washing the engine bay, the car loses all electrical power whenever the starter is engaged. Power can be temporarily restored by disconnecting and reconnecting the negative battery cable, but engaging the starter again kills all power. Battery shows 12 volts, all fuses appear OK, and the immobilizer was ruled out.

Total loss of electrical power when starter is engagedLights and accessories work normally until starter engagesPower can only be restored by disconnecting and reconnecting negative battery cableBattery shows 12 volts at terminalsFuses all appear functional

Root Cause

Corroded and dirty ground connections at the battery negative terminal and chassis/engine grounds. The high current draw of the starter motor exposed the poor ground connections, causing a voltage drop that effectively killed all electrical power. The engine wash likely worsened existing corrosion on the old ground connections.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted September 2021 on SupraForums.com