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Gone but not forgotten
1,288 Posts
Discussion Starter #1 (Edited)
This is a new twist on the IAT mod that gives your Magnum engine a few more ponies. This mod was developed to fix the two issues that the standard permanent moving of the IAT causes; lower MPG, & clogging of the catalytic converter sooner.

Parts you will need to complete this mod:
Double-Pole-Single-Throw Switch
6 Foot of 3 conductor wire 20 gauge
New IAT Sensor
*Rubber grommet, simple way to install the IAT into the new location.
*IAT wiring harness pigtail
*K&N Air Filter Part # E-1100 Recommended for optimal HP gain with this mod.
*Heat Shrink tubing
*Optional but recommended for the professional/show look

Tools needed:
Drill and bits, unibit
Wire Strippers and wire cutter
Soldering Iron or Gun with solder
Zip Ties
Screw drivers as needed
Ratchet and sockets as needed
Heat gun or hair dryer (Do not recommend using lighter or matches near your engine)
Black electrical tape

Always disconnect the battery when doing any electrical work!

Here is the wiring diagram I designed:

Substitute the gray wire for the white wire listed below in the soldering instructions.

First pick a location as to where you want the switch and lights to be mounted. (I chose the electric mirror control location due to my van not having that option) Be sure that there are no obstacles behind where you plan on putting them and that they are in easy reach as you drive the vehicle. Once you are sure of where you want them then drill the hole the size of the switch.

The wire I used had 4 conductors (red, green, white, black and shielding) I cut the shielding and black wire off. On the switch I soldered the green to the up side of the switch so that when the switch is in the down position it would be using the original IAT sensor. Then the red wire I soldered to the lower terminal of the switch so that when the switch is flipped to the up side then the new IAT sensor will be working. I used the white wire to bring the PCM power from the harness to the switch.

Remove the air cleaner housing so that you can mount the new IAT sensor. I drilled mine into the snorkel and used a grommet to hold the sensor in place. Be sure not to over drill or the grommet will not fit snuggly with the sensor pushed into it.

I also used a dremel tool with a grinding stone to remove the burrs from inside the snorkel. Now mount the grommet and new IAT sensor.

Take the 3 conductor wire bundle and feed it through the Firewall, You can notch the Throttle Cable Boot or carefully drill a hole and use a wire grommet and push the wire through it.

INSIDE route the wire to the switch and be sure it will not get pinched or yanked, leave a about 6 inches extra to work with (more if you found a good but tricky place to mount your switch). In the engine bay route the wire along the firewall across the PCM and down towards the right side of the engine near the original harness. I brought mine behind the alternator.

If your new wiring has the shielding you can use it if you wish. If you choose to only attach one end of it, not both. I chose to connect mine to the alternator body ground terminal (see above pic). The shielding will stop most if not all electrical interference from ignition, alternator and such. THE SHIELDING IS NOT NEEDED FOR THIS MOD.

I looped my wire below the alternator and bought it up about 4 inches. I cut the original IAT harness. I then soldered the wiring as follows starting with the new wiring harness:
White wire to the Black with Red strip still attached to the original engine harness
Red wire to the new IAT sensor
Green wire to the old IAT sensor
I then took the Black with Blue strip wire (which ground to the vehicle) and connected it back to the old IAT harness and the new IAT negative wire.

I tested the connection back to the switch to be sure all was working well.
Test using a ohm meter/setting from the white wire to the green and red. It should indicate that the connection is good from the white to green when the switch is in the down (economy) position and nothing between red and white. Then test the white to red and it should work when in the up (power) position and should be no reading when connected to the green wire. On my new wiring harness it had a shielding wire I attached this to the alternator body ground.

After you have tested the system apply the heat shrink tubing and/or liquid electrical tape. For the factory finish look I applied electrical tape to the new wiring. You can even use convolute wiring cover for parts of the new wire for a really nice factory and show vehicle look.

Reattach the air cleaner and connect both the new and old IAT sensors.

Don't forget the K&N air filter for best performance with this MOD.

Reconnect the battery and test run the engine. Enjoy your new Switchable IAT MOD.

4 Wheel Power Disc Brakes
5,828 Posts
Good work. It should be a how-to article.
I'm glad someone took the bull by the horns and did this...I made a suggestion a few years ago (Power/Economy mode).

Seating for 12
1,893 Posts
Amazing write up. :)

This I'll have to do as well.

Make this a sticky once you have tried the mod out.

Gone but not forgotten
1,288 Posts
Discussion Starter #4
Did try it out this evening, family and I went for a test drive while going out to dinner. Not a great boost but trying it out at heavy take off throttle on the highway entrance ramp I did feel it kick in a little when I flipped the switch.:tup:

More tests to follow in the next few weeks.

Anyone doing this mod please post your results as well.
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