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Ignition Control Module (TFI) Re-location

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Old Dec 10, 2020 | 02:52 PM
  #1  
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Ignition Control Module (TFI) Re-location

After changing my distributor earlier this year it looks as though my TFI module is on the blink, even though it has heat sink paste on it. So I've been reading up on relocating the module away from the engine. I've read some threads and I'm inclined to buy a kit from McCully or FatFoxx.

I have a question related to the wiring from the newly relocated module to the existing main harness connector. I don't want to peel that harness back if I can avoid it.

Why not cut off the connector and splice wires to extend it out to the new location of the TFI module?
I do see that McCully offers a kit with a harness extension (made out of a gutted old TFI module) but the kit total price is $170.

I'm seeking input from anyone who has done this.

Thanks.
 
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Old Dec 10, 2020 | 03:16 PM
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You could cut and splice by soldering and heat shrink tubing the wires PLUS use shielded wiring, just like the factory. To cover over the spliced/soldered area use foil tape to bridge the gap and keep the shielding intact.
 
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Old Dec 10, 2020 | 05:35 PM
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Originally Posted by Gee150
After changing my distributor earlier this year it looks as though my TFI module is on the blink, even though it has heat sink paste on it. So I've been reading up on relocating the module away from the engine. I've read some threads and I'm inclined to buy a kit from McCully or FatFoxx.

I have a question related to the wiring from the newly relocated module to the existing main harness connector. I don't want to peel that harness back if I can avoid it.

Why not cut off the connector and splice wires to extend it out to the new location of the TFI module?
I do see that McCully offers a kit with a harness extension (made out of a gutted old TFI module) but the kit total price is $170.

I'm seeking input from anyone who has done this.

Thanks.
I just purchased the McCully kit. It should arrive tomorrow. The more expensive kit is $170, but they offer a cheaper mk2 kit for $65 (plus $10 shipping). I think the $170 conversion kit is better if you want to easily remove and replace the kit in the future.
McCully Racing Motors- Products


 
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Old Dec 10, 2020 | 05:51 PM
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Originally Posted by Gee150
I have a question related to the wiring from the newly relocated module to the existing main harness connector. I don't want to peel that harness back if I can avoid it.
I'm reading through the installation directions now, I see what you mean. I didn't realize the cheaper kit only includes one side of the harness. I'll see how it goes...
 
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Old Dec 10, 2020 | 06:05 PM
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Originally Posted by Gee150
After changing my distributor earlier this year it looks as though my TFI module is on the blink, even though it has heat sink paste on it. So I've been reading up on relocating the module away from the engine. I've read some threads and I'm inclined to buy a kit from McCully or FatFoxx.

I have a question related to the wiring from the newly relocated module to the existing main harness connector. I don't want to peel that harness back if I can avoid it.

Why not cut off the connector and splice wires to extend it out to the new location of the TFI module?
I do see that McCully offers a kit with a harness extension (made out of a gutted old TFI module) but the kit total price is $170.

I'm seeking input from anyone who has done this.

Thanks.
If you have the skill, a soldered connection would be better than the spade terminals offered on a harness extension. More connections, more places to fail. As previously mentioned by rla2005, using shielded cable and wrapping your splice would be optimal.
 
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Old Dec 10, 2020 | 09:03 PM
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Originally Posted by midwestbird
I'm reading through the installation directions now, I see what you mean. I didn't realize the cheaper kit only includes one side of the harness. I'll see how it goes...
This is what I see when comparing the kits:

The basic McCully kit provides no shielded harness wiring which would allow you total freedom to relocate the TFI. So you have to buy that if you need it.
You pay an extra $100 for the ready to go harness. The McCully TFI to Distributor cable already has connectors pre-installed.

The FatFoxx kits includes the necessary DIY harness wires.The FatFoxx kits have longer wiring than the McCully. Also the FatFoxx has front and side mount option kits.

Unless there's some fundamental difference in the quality I think the FatFoxx is the way to go unless you want the $170 McCully plug and play kit.

I still don't see the need to peel the harness back. It looks to me like cutting off the TFI connector and extending the harness is the way to go, but I may be overlooking something.

Example Installation of FatFoxx Kit:




McCully Kit - No Harness Wires:
36" TFI to Distributor Wire.





McCully Kit with Ready to go Harness Extension:

Picture does not show the 40"TFI to Distributor Wire but it is in the kit.



FatFoxx Kits:
Basic Kits 9'6" TFO to Distributor Wire.



Originally Posted by rla2005
You could cut and splice by soldering and heat shrink tubing the wires PLUS use shielded wiring, just like the factory. To cover over the spliced/soldered area use foil tape to bridge the gap and keep the shielding intact.
Yes. I used the term "splice" generically. Your comments are dead on.
 
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Old Dec 11, 2020 | 09:20 AM
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What is the shielding for, exactly? I extended mine using good old fashioned solder and heatshrink, but think the harness extender is the best way.
 
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Old Dec 11, 2020 | 10:13 AM
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I've got all the pieces/parts leftover from about 3 remote mount harnesses in the junk box & a 92 5.0 GT with the original set up.

Thought about doing the conversion, but might mock it up for the day the original 120K ICM kicks.
 
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Old Dec 11, 2020 | 01:11 PM
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Originally Posted by jackietreehorn
What is the shielding for, exactly? I extended mine using good old fashioned solder and heatshrink, but think the harness extender is the best way.
The shielding is there to prevent RF/electronic noise from interfering with the ignition signal wires. The longer the wire (read that as "antenna") the more susceptible the circuit is to electronic noise. It's the same reason why the coax (RG-59) that feeds your television has an outer shield. The shielding acts in both directions...external noise as well as any "noise" generated by the wires inside.

1992 F-Series



Notice the shielding is grounded only on one end.
 
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Old Dec 11, 2020 | 03:35 PM
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Originally Posted by rla2005
The shielding is there to prevent RF/electronic noise from interfering with the ignition signal wires. The longer the wire (read that as "antenna") the more susceptible the circuit is to electronic noise. It's the same reason why the coax (RG-59) that feeds your television has an outer shield. The shielding acts in both directions...external noise as well as any "noise" generated by the wires inside.



Notice the shielding is grounded only on one end.
That's an interesting diagram and different to the one in my 1991 EVTSM Manual. Agreed on Shielding. Sorry about image quality.









 
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Old Dec 11, 2020 | 03:38 PM
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Originally Posted by Gee150
That's an interesting diagram and different to the one in my 1991 EVTSM Manual. Agreed on Shielding. Sorry about image quality.

The diagram I posted is for a 1992 which was the first year the small block trucks got the remote mount ICM.
 
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Old Dec 11, 2020 | 04:17 PM
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Originally Posted by rla2005
The diagram I posted is for a 1992 which was the first year the small block trucks got the remote mount ICM.
Makes sense now.
 
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Old Dec 11, 2020 | 04:42 PM
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I see that McCully includes Arctic Silver 5 compound in their kit to use on the heatsink. Does anyone have any experience with this? It looks like I will install my new (under lifetime warranty) distributor and ICM as factory before I buy a remote mounting kit and get it installed. I don't want the truck to quit on me in the next few days. So I'll need to use a good compound and wipe off whatever is on the Carquest ICM.
 
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Old Dec 11, 2020 | 05:33 PM
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My ICM crapped out last weekend. A new one is in the mail and I figured now is the time to install a TFI relocation kit. I should have done my homework though. I ordered the mk2 McCully kit and -- like I said above -- it's on its way. I assumed it included everything I needed but was disappointed when the online instructions said I can have them build an extension harness, if needed. I too am not especially interested in tearing into my wiring harness. So, I emailed McCully to ask about making me an extension harness but he said he no longer builds them; I'd need to upgrade to the $170 mk3 kit. I'll probably just end up doing that but I want to first look the mk2 kit over when it arrives. I'll check out the fatfoxx video you posted too.
 
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Old Dec 11, 2020 | 06:56 PM
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I think using a gutted ICM module is an ugly fix. Especially for $100. But....easy if you like it.
 
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