DIY AEM F/IC Harness Resistor Mod
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Joined: Dec 2007
Posts: 2,603
From: South Florida
DIY AEM F/IC Harness Resistor Mod
For this DIY I actually included pics! lol. Actually the pics make it much more helpful since we'll be splicing/wiring 4 wires on a Boomslang harness.
Parts:
Boomslang harness for F/IC
Soldering Iron
(2) 2.2k ohm 1/2 watt resistors
Razor blade
Electrical tape
This mod is very easy. The trickiest part is stripping the wires. And some of you may ask, "if I don't have stuttering issues, can I do this anyway?" Yes you can! It won't hurt anything if you do the mod. So here we go..
Here's what the Boomslang harness looks like. We'll be soldering on the side where it plugs to the F/IC (black connectors). Notice there are two connectors - one is 24 pin and other is 22pin.
Here's the resistors you need. $0.99 for a pack of 5 - good deal! lol
Here's the pic comparison of the supplied F/IC harness (not used) vs the Boomslang (right side). We're looking at the 24pin. We'll be messing with the wires on the 9 and 10 pinouts.
Here's the other 22pin connector. We'll be messing with pinouts 8 and 19.
Pic of the two resistors needed - and my trusty blade.
These next two pics show how the wires were carefully stripped with the razor blade. Take your time on this.
Wires of pin 9 and 10 (Cam1 + / -)
Wires of pin 8 and 19 (Crnk1 + / -)
You now want to tin the bare wires. This means you want a coat of solder on the wires. Here's how they look:
Next you want to take the resistor and wrap the ends on each wire... and snip off the excess. Then solder the connection.
Now all you need to do is wrap this up with electrical tape and you're done!
This was a pretty quick mod.
Parts:
Boomslang harness for F/IC
Soldering Iron
(2) 2.2k ohm 1/2 watt resistors
Razor blade
Electrical tape
This mod is very easy. The trickiest part is stripping the wires. And some of you may ask, "if I don't have stuttering issues, can I do this anyway?" Yes you can! It won't hurt anything if you do the mod. So here we go..
Here's what the Boomslang harness looks like. We'll be soldering on the side where it plugs to the F/IC (black connectors). Notice there are two connectors - one is 24 pin and other is 22pin.
Here's the resistors you need. $0.99 for a pack of 5 - good deal! lol
Here's the pic comparison of the supplied F/IC harness (not used) vs the Boomslang (right side). We're looking at the 24pin. We'll be messing with the wires on the 9 and 10 pinouts.
Here's the other 22pin connector. We'll be messing with pinouts 8 and 19.
Pic of the two resistors needed - and my trusty blade.
These next two pics show how the wires were carefully stripped with the razor blade. Take your time on this.
Wires of pin 9 and 10 (Cam1 + / -)
Wires of pin 8 and 19 (Crnk1 + / -)
You now want to tin the bare wires. This means you want a coat of solder on the wires. Here's how they look:
Next you want to take the resistor and wrap the ends on each wire... and snip off the excess. Then solder the connection.
Now all you need to do is wrap this up with electrical tape and you're done!
This was a pretty quick mod.
......i dont have my laptop yet 
Thread Starter
Senior Member
SL Member
Joined: Dec 2007
Posts: 2,603
From: South Florida
This was intended for those who have the stuttering issue in higher rpms with the F/IC. It's happened on several TCs regardless of year. However, even if you don't have the issue, the mod won't negatively affect your tune.
whats happening is the VEHICLE creates a small amount of noise on the crank/cam sensor signal wiring - the fic interprets this as a timing pulse and outputs an additional timing pulse throwing the cars timing out of whack
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1UP Crew
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Joined: Dec 2004
Posts: 3,044
From: VA
Originally Posted by thendawg
whats happening is the VEHICLE creates a small amount of noise on the crank/cam sensor signal wiring - the fic interprets this as a timing pulse and outputs an additional timing pulse throwing the cars timing out of whack
Thanks for clearing that up...ive been trying to figure out what could be causing noise that ppl were talking about
Nice writeup B_real......glad to know if I every do this mod, I already have all the tools/parts needed thanks to school!,
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1UP Crew
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Joined: Dec 2004
Posts: 3,044
From: VA
Sorry if this is a threadjack but this is the most detailed thread I have seen on this on SL but Is this mod only for "noise" in the wires?
If the harness was getting noise, wouldnt you want to "shield" the wires since noise is like an interference, sort of like what could happen when you cross power wires with speaker wires when hooking up an amp... I see how the resistors could help with the voltage fluctuations in resisting to 2.2K ohms tho, just looking for more details to this mod.
and Excuse me if I sound like an idiot, im still learning this in school lol which is also why I want to learn more about this particular mod...
If the harness was getting noise, wouldnt you want to "shield" the wires since noise is like an interference, sort of like what could happen when you cross power wires with speaker wires when hooking up an amp... I see how the resistors could help with the voltage fluctuations in resisting to 2.2K ohms tho, just looking for more details to this mod.
and Excuse me if I sound like an idiot, im still learning this in school lol which is also why I want to learn more about this particular mod...
Thread Starter
Senior Member
SL Member
Joined: Dec 2007
Posts: 2,603
From: South Florida
Caveman,
From AEM's website:
From AEM's website:
Originally Posted by AEM FORUMS
We have seen a couple of vehicles, including an automatic Scion xB, that had erratic misfires (especially at high load) that would go away if you bypassed the cam or crank signals so they were not intercepted by the FIC. After measuring the signals with an oscilloscope, we could see that the signals were a bit noisy, and the FIC inputs were sensitive enough that they picked up noise and sent an extra cam pulse to the ECU. The solution was to install a 2k ohm resistor with one side connected to Crank MAGI(+) and the other side connected to Crank MAGI(-). Another 2k resistor installed with one side connected to Cam1 MAGI(+) and the other side connected to Cam1 MAGI(-).
