Starter Relay Mod Wiring - Correct 4-Pin Relay Configuration

Electricalintermediate✓ OP Confirmed

Problem

When performing the starter relay mod on a 7MGTE Supra, the correct wiring configuration for the 4-prong relay is unclear due to conflicting information between video tutorials and forum posts regarding which pins go to battery vs starter.

Confusion over correct relay pin assignments (30 vs 87 to battery)Uncertainty about where to source the trigger signal (pin 86)Starter relay mod not working due to incorrect wiring

Root Cause

The stock starter circuit suffers from voltage drop through aging wiring and connectors. The starter relay mod bypasses this by adding a dedicated relay that provides full battery voltage directly to the starter solenoid, but conflicting wiring diagrams online cause installation confusion.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted July 2021 on SupraForums.com