TFI Ignition Module Failure

Page Revised: 10 May 2019


Article by
Eric Dess

The TFI ignition module controls the spark on your car's engine, but when it fails it can cause multiple problems. Things got so bad with TFI failures that there was a class action lawsuit in the early 2000s. As ominous as this sounds, take heart in knowing that the worst of the issue is resolved by now. Still, the TFI can fail just like any other electrical part. Here is important information that you need to know about the Ford TFI module.

What is a TFI module?
TFI stands for Thick Film Ignition. The module itself consists of some solid state electronic components suspended in a thick, clear electrolytic film, hence the name TFI.

What is the TFI module's function?
The TFI module (also known as a spark module) is necessary to control the spark output of the ignition system via the EEC (electronic engine control) computer. A signal from the TFI module is sent to the EEC and the computer then controls the spark to the spark plugs. It is a very necessary and vital component of the entire EEC-IV engine management system.

Where is the TFI module located?
Depending upon the engine configuration, the module is usually found on the distributor itself, on the front of the motor:

This module is located on the side of the distributor. Shown here is a 1986-88 Cougar 5.0 V8 engine.

TFI Module

On some cars, the module has been relocated to the front of the radiator core support and is surrounded by an aluminum heat sink. The module above is on a 1988 Cougar with the 3.8 V6 engine.

TFI Module

What is the problem with the modules?
Due to excessive heat from the engine, the module has been known to stop working or intermittently work, resulting in stalling or cutting out of power to the vehicle's ignition system. This situation has been known to cause stalling and accidents, although it is not clear whether any accidents resulted in serious injury or death.

What Ford vehicles are affected by this problem?
Any Ford vehicle with the EEC-IV engine system, from late-1983 through the mid-1990's, has a TFI spark module, including Cougars and Thunderbirds. Pre-1983 vehicles do not have this module. Vehicles with DIS (distributorless ignition system) also do not have a spark module.

I'm concerned. What should I do with my vehicle?
If you are concerned about your car's TFI module, the first thing you should do is have a qualified mechanic inspect it physically. This requires removal with a special tool. There are two Torx screws sunk into the module that hold it to the distributor (or heat sink). Once they are removed, the module unsnaps from its base, and then the wiring harness can be unhooked. On the top (grey) side is an inspection cover, under which is the thick film. There should be no seepage of film, nor should the film be dried up. Also, the plastic around the mounting screws should not be cracked at all. Any cracks will allow the module to pull away from its base, cutting out power and possibly hampering ignition. The module's halves should be flush and fitted tightly against one another. There should be no brownish discoloration at the harness end. Finally, there should be a generous spattering of dielectric grease (clear or white in color) on the metal backside of the module. This is to help promote electrical conductivity with the base. Upon replacement, the old grease should be wiped off and a new fresh coat applied, approximately 1/32 of an inch thick. Be sure to inspect all wiring around the module to make sure there are no breaks or pinholes that may short out the system. In an electrical test with an ohmmeter, the TFI module should be below 800 ohms or over 975 ohms. If the module falls between 800 and 975 ohms, it must be replaced.

Can I replace the part myself?
If you feel that you can do this yourself, the tool to remove the module is only a few dollars at any good auto parts store. Be sure to disconnect the vehicle's battery before attempting to remove this or any other electrical component of the car. Use a name brand TFI module to be sure you are getting a quality part. We highly recommend using a Motorcraft TFI if possible. The cost of the part itself should be anywhere from US $15-$50 for your vehicle. Keep in mind that there is no guarantee that the new part will be assembled better, or less prone to the problem, than the old module. However, a new module will at the very least provide more accurate information to the computer and is very inexpensive insurance.

Owners of vehicles with the TFI modules mounted on the radiator core probably will have fewer problems with excessive heat affecting the module. This is because of a large heat sink (dissipator) around the module itself, and the cooling effect of incoming air as you drive. However, it is still recommended that you have it inspected for other problems mentioned above.

Should you wish to relocate your distributor-mounted TFI to the front radiator core (or really, any other free spot that gets good airflow), it is possible to purchase a TFI relocation kit. It will come with a wiring harness extender, the heat sink, and all appropriate hardware and instructions. Some companies offering TFI relocation kits include MuCully Racing Motors and Fat Foxx. This is an excellent way to solve an issue that the factory never got right.