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Brian, Auto Service Technician
Category: Ford
Satisfied Customers: 1227
Experience:  5 years Ford Technical Hotline/Service Engineer. 2005 Ford Master Cert. Automotive Technology degree
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fixing hyper flashing on turn lamps

Resolved Question:

2001 Mercury Gran Marquis LS, 4.6L
LED''s bulbs replacing filament OEM
Submitted: 8 years ago.
Category: Ford
Expert:  Brian replied 8 years ago.
The LED lights are such low resistance, that the flasher reacts by rapid-flashing. You will need to add some resistance to the circuit. Most places that sell LED's on the internet offer load resistors that can be added to make the circuit more like the original bulb resistance so the flasher will see the proper amount of current flow.

Here is an example from


One LOAD Resistor is required for each turn signal bulb

6 Ohm, 50 Watt resistors can be connected across the turn signal bulbs to simulate the load of a regular filament bulb (2 Amp load). This will solve LED related turn signal problems such as hyper flashing or burnt out bulb indications. Resistor measures 1.96L x .64W x .60H inches, leads are 12 inches long.
Kit Includes gel filled moisture resistant splice taps.

CONNECTION INSTRUCTIONS: Using included splice taps, connect one wire to ground and the other wire to the turn/brake hot wire. Splice taps allow for installation without cutting your turn signal wires.

We also offer 25 Ohm, 25 Watt Load Resistor kits which can be used with LED side marker lights (194/168 type) to prevent bulb-out indicators from turning on.

InstallationBuy Now

load resistor kit

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Customer: replied 8 years ago.
I'm told that resistors produce excesive heat, resistor need to be in flat contact with car's metal to cool resistor, if this is thrue I would like better to work with a NO-LOAD ELECTRONIC FLASHER DIRECTLY IN THE LCM. the question is; which part number will do the trick?.
Customer: replied 8 years ago.
Do I expect answer to this one? or your work is done already?
Expert:  Brian replied 8 years ago.
I misstated that LED's have low resistance, I meant to say they have low current flow. The lighting control module does not have a separately replaceable flasher. It is already an electronic flasher, but it is designed to work with a certain amount of load (the original bulbs).

I don't know of any way to modify the LCM to work with LED bulbs, but if you found some electrical engineering guru who could reverse engineer and modify the circuitry, maybe you could do it.

Otherwise you would have to completely bypass the LCM, and that would require a good bit of rewiring.

Here are some diagrams to show the stock setup:

To get the no-load flasher installed, you would have to cut the two wires in this diagram labeled flasher power input and flasher output, and connect them to the aftermarket no-load flasher instead. Then you would have a third ground wire on your aftermarket flasher to connect to ground somewhere under the dash or add it to a pre-existing ground point. Make sure to tape off the cut ends so they don't short out and damage your LCM. I don't know how the LCM will respond to this modification, you may get codes as a result. There could be unexpected results. But it should work the LED's.

The LCM is located under the dash, to the right of the steering column. It has three connectors on it.

Here is a page with a lot of info about Ford LCM's:
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