TFI IV Ignition Module Tests

[SC Car Dude]

Here is a diagram I made to teach people how to test their TFI IV Module (the one attached to the distributor) since failure of this part will cause dangerous, unexpected stalling (such as at an intersection, on the interstate, or driving through the ghetto at night.)

If you are not sure about the condition of yours please take a few minutes to disconnect it and test it. Better to replace it before you get t-boned or rear-ended than after, assuming you and your family and friends survive.

"TFI" stands for "Thick Film Ignition" but the "Thick" refers to a clear gel layer inside of the module which helps wick away heat from a circuit board, not the paste on the outside of the module. The metal side of the module requires a heat-conductive paste (such as Arctic Silver 5) and should be applied in as thin of a layer as possible while maintaining even coverage.

If you are able to it is best to relocate the TFI Module by taking it off the scorching-hot distributor and mounting it some place away from engine heat. This greatly increases the reliability, but requires a good bit of effort, materials, and competence; and guides on how to accomplish this are elsewhere on the internet so I won't describe the process here.

Testing the module is easy: You just check to see if it has power going to it, then check the terminals for the proper amount of resistance using an ohm-meter or a multi-meter. Knowing for sure the condition of your module will prevent you from wasting money on a new one because they are rather expensive.

Remember - just because your module tests okay right now doesn't mean it will be okay a year from now. Everything deteriorates with use, and the older your module is the more likely it is time for it to fail.

If this diagram helps just one person I will have accomplished my goal.
Study it carefully and good luck!

[phantom_smack]

And remember you get what you pay for in ignition parts

[SC Car Dude]

Exactly. Motorcraft is probably the best replacement, and is probably the most expensive.

[theoldwizard]

Originally Posted by SC Car Dude

"TFI" stands for "Thick Film Ignition" but the "Thick" refers to a clear gel layer inside of the module which helps wick away heat from a circuit board,

Nice guess but your are incorrect (I worked in Ford's Electronic Division just down the aisle from the folks who designed that part.) The gel simply seals the circuit board and electrical components from moisture.

Thick film refers to the "circuit board" (in this case it is actually ceramic) and the way the conductors are placed on the board (via a type of "ink"). Small resistors are actually "inked" on (different ink).

Heat from the main power transistor is transferred via a heat spreader slug out the backing plate as you correctly stated.

If you are able to it is best to relocate the TFI Module by taking it off the scorching-hot distributor and mounting it some place away from engine heat. This greatly increases the reliability, but requires a good bit of effort, materials, and competence; and guides on how to accomplish this are elsewhere on the internet so I won't describe the process here.

You can find TFI's mounted to a big aluminum heat sink that can be remotely mounted on a fender. Unfortunately then you need an extensions harness. These sometime show up on eBay.

If this diagram helps just one person I will have accomplished my goal.
Study it carefully and good luck!

I will only add that some model year had an issue with the rubber grommet between the PIP sensor inside the distributor and TFI. When this failed the PIP shorted out.

Also early TFI had a bad habit of destroying the E Core coil as they went south.

[mark v]

Sticky approved!

[SC Car Dude]

"Nice guess but your are incorrect"

I stand corrected. Thanks for the info.

[theoldwizard]

SC, I just noticed your avatar.

We "affectionately" called that gel "gorilla snot". I can not repeat what we called the thermal paste.

[kansasr]

Originally Posted by SC Car Dude

Here is a diagram I made to teach people how to test their TFI IV Module (the one attached to the distributor) since failure of this part will cause dangerous, unexpected stalling (such as at an intersection, on the interstate, or driving through the ghetto at night.)

If you are not sure about the condition of yours please take a few minutes to disconnect it and test it. Better to replace it before you get t-boned or rear-ended than after, assuming you and your family and friends survive.

"TFI" stands for "Thick Film Ignition" but the "Thick" refers to a clear gel layer inside of the module which helps wick away heat from a circuit board, not the paste on the outside of the module. The metal side of the module requires a heat-conductive paste (such as Arctic Silver 5) and should be applied in as thin of a layer as possible while maintaining even coverage.

If you are able to it is best to relocate the TFI Module by taking it off the scorching-hot distributor and mounting it some place away from engine heat. This greatly increases the reliability, but requires a good bit of effort, materials, and competence; and guides on how to accomplish this are elsewhere on the internet so I won't describe the process here.

Testing the module is easy: You just check to see if it has power going to it, then check the terminals for the proper amount of resistance using an ohm-meter or a multi-meter. Knowing for sure the condition of your module will prevent you from wasting money on a new one because they are rather expensive.

Remember - just because your module tests okay right now doesn't mean it will be okay a year from now. Everything deteriorates with use, and the older your module is the more likely it is time for it to fail.

If this diagram helps just one person I will have accomplished my goal.
Study it carefully and good luck!

Thanks for the Info on the ICM, I have a 1996 Bronco XLT 5.8 liter and am currently having issues concerning this System.
The bronco is intermittently stalling/shutting off with no warning, then not wanting to start, so on the advise of a tech I replaced the ICM what I got was a grey ICM, instead of the Black Motorcraft one. This changed things a bit but not completely.
The Black one was intermittently stalling and throwing P0320,
The Grey one was intermittently stalling and throwing P1351 and P1359, but not P0320.
Now from what I can see this is a real pain issue, some say the catalogs\books are wrong and instead of the Grey Model it has to be the Black one and as I can tell they are definitely different issues. I also have the FORD service manuals to reference.
I have changed the CKP(Chrankshaft Position Sensor), Distributor Cap, Rotor, Plug Wires and originally the ICM. Other then stated nothing has stopped the Stalling\Dieing.
I have cleaned all the connectors and still to help, any ideas would be helpful.
What is the problem with the different ICM's?

[theoldwizard]

The TFI system does not use a Crankshaft Position Sensor. It uses a PIP (Profile Ignition Pickup) Sensor inside the distributor.

[kansasr]

Ok so that was a waste but do you have any other idea's?