Car Randomly Dying After 5-15 Minutes of Driving - Faulty Alternator Despite Passing Bench Test

Electricalintermediate✓ OP Confirmed

Problem

1992 MK3 7MGTE automatic would randomly shut off after driving for 5-15 minutes. The car ran fine under normal conditions but would stall and refuse to restart, even with 12-13V showing at the battery. The alternator had been bench-tested at AutoZone and passed, the battery was confirmed to be charging, all fuses were good, and no shorts were found in the wiring harness.

Car randomly shuts off after 5-15 minutes of drivingRadio shuts off shortly before engine diesEngine just stops with no other warning signsBattery shows 12-13V but car refuses to turn over or engage starterCar will start again the next day and repeat the cycleRuns fine under normal conditions before dying

Root Cause

Faulty alternator that passed a bench test at AutoZone but failed under real-world operating conditions (likely an intermittent failure triggered by heat soak after 5-15 minutes of driving)

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted January 2025 on SupraForums.com