LED Turn Signal Hyper-Flash Fix for 86.5-88 Supra - Flasher Adapter Harness

Electricalintermediate✓ OP Confirmed

Problem

After converting exterior lights to LED on a 1986.5-1988 Supra, the turn signals hyper-flash because the OEM thermal flasher relay detects the lower LED current draw as a bulb-out condition. Unlike 89-92 Supras, no aftermarket LED flasher is a direct plug-and-play replacement because the 86.5-88 models use a different, tighter pin spacing on Relay Box #5 (flasher part number 81980-16010).

Turn signals hyper-flash (blink rapidly) after LED bulb conversionBulb-out warning indicator on dashboard illuminated constantlyStock flasher relay may overheat or stop flashing entirely after prolonged use with LEDsHazard lights may miss beats or stop blinking if not all bulbs are connected

Root Cause

The 1986.5-1988 Supra uses a flasher relay with a narrower pin spacing in Relay Box #5 than the 1989-1992 models. No aftermarket LED flasher matches this pin configuration directly. The OEM flasher uses a current-sense resistor calibrated for incandescent bulbs (~2.2A per bulb), so the much lower LED current (~235mA per bulb) triggers the fast-flash bulb-out detection.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted April 2020 on SupraForums.com