Tail/Parking/Instrument Lights Out - Cut Alternator Wires, Wrong Fuses, and Failed Integration Relay #2

Electricalintermediate✓ OP Confirmed

Problem

Tail lights, parking lights, license plate lights, and instrument panel lights were all out. No power was being supplied from the tail light relay. The tail light relay would not click/energize when the light stalk was turned on.

No tail lights, parking lights, license plate lights, or instrument illuminationNo power output from tail light relayTail light relay does not click when light stalk is turned onIncorrect amperage fuses installed throughout fuse box (30A in tail instead of 15A, 25A in mirror instead of 10A, 20A in dome instead of 7.5A)Two cut black wires found under engine bay fuse boxAlternator wired directly to battery bypassing engine fuse boxNo power at 1A connector terminal #3 at Junction Box #1Headlights do not auto-off when opening door after shutting off ignition

Root Cause

Three compounding issues caused by a previous owner: (1) Incorrect oversized fuses installed throughout the fuse box, risking wire damage. (2) Two black wires from the alternator to the engine fuse box were cut, and the alternator was wired directly to the battery, which eliminated the power feed to Junction Box #1 terminal 1A-3 that supplies the tail light relay, stop lights, rear defogger, mirror heaters, and dome light circuits. (3) The Integration Relay #2 module (auto-off lights module above driver's left knee) had failed internally and was not passing the ground signal from the light switch through to the tail light relay coil terminal #1, preventing the relay from energizing.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted October 2023 on SupraForums.com