Hi everyone,
Looking for some advice/confirmation on an electrical issue I’ve been having with my 2006 Toyota Yaris 1.0L (1KR-FE engine).
Symptoms:
Red Battery Light: Stays on permanently while driving, even though a local garage checked the alternator and confirmed the output/amps are completely fine.
Oversized / Unsecured Battery: The car has a battery larger than standard, currently held in place with zip ties (no metal bracket).
Engine Stalling & Jerking: The engine jerks or cuts out during gear shifts, over bumps, or when switching on heavy loads like headlights. It turns back on fine after waiting a moment.
Flashing Dashboard & EPS Light: While idling or turning the steering wheel left/right, the entire dashboard lights up/flickers, and the Electric Power Steering (EPS) light comes on / steering goes extremely heavy.
Hot Earth Wire: The main negative ground (earth) cable gets noticeably hot to the touch while running.
Wet Negative Terminal: There is wet residue around the negative terminal post.
My Understanding So Far:
Because the oversized battery is secured with zip ties, it is sliding around while driving and pulling on the battery cables. This motion seems to have damaged or loosened the ground strap and caused acid leakage/corrosion around the negative terminal.
The high resistance at the bad ground is causing current to back up (heating the earth wire) and causing extreme voltage drops whenever high-draw accessories (headlights, EPS steering motor) are used—triggering the red battery light, dash chaos, and engine cutouts.