Quick Links

MKIII Supras




Cygnus Tech

Groupama Saga

MKIII Supra Lamp Fail Module Bypass

This mod will allow you to bypass the troublesome lamp fail module (LFM).

If your side lights or brake lights have stopped working or your handbrake or yellow lamp fail light will not extinguish on the dash despite the brake fluid level being good and all bulbs OK in the light clusters, chances are your LFM has failed.

You may also want to remove this unit from circuit if you upgrade to LED lights or if the units been destroyed by leaking light seals.

The LFM is a small box - often blue - located below the drivers side light cluster when accessed through the flap in the trunk plastics.

You cannot simply just unplug this unit to clear the fault lights as, the stop and tail lights (stupidly) wire through it internally.  It usually fails due to water ingress from tired light seals or burns out due to the use of current shunts on the PCB.

To remove the unit from the circuit you will need to make the links detailed below at the LFM multi plug.  This will then allow you to remove the unit completely.  Only detailed wires need to be linked, all others can be ignored.


I strongly advise you do not use the “Scotchlock” type line taps to join the cables as they are extremely unreliable & provide a very poor connection.  Soldering & heat shrink is the best option.

LFM Bypass02

If your car is not fitted with a 3rd high mount brake light then you will not need to link the Red/White wire.

If you have an import car with the LED spoiler mounted brake light then, the Red/White wire is usually missing all together and the LED brake light taps into the stop light signal else where in the wiring loom before the LFM so, is usually unaffected by LFM issues & the red/white wire is missing. 

The same applies for other factory fit high mount brake lights, these can also tap into the brake light supply at different points so, do not appear at the LFM.

Full circuit diagrams of the lighting systems that pass through the LFM can be found here:  Stop lights  Tail lights

If you found this guide helpful or have a comment, please sign my Guest Book or use the Message Board.

If you found this guide helpful or have a comment, please sign my Guest Book or use the Message Board.