Thats right, finally a way to high idle your 03-04 truck manually. I tested and confirmed this method this morning on my 03.5. I would like some early 03s and 04s to try this and to confirm if it works for them also.
Once this is tested by some other members and confirmed, can a admin maybe sticky this, and let me know what needs to be done to get it added to wiki. I will take detailed pictures of my setup in couple days.

What you need:
-A single pole double throw switch that is On/On it will have 3 terminals
-Some butt connectors/spade connectors
-Some wire
-A 47k 1/4 watt resistor

The method: (Note: this envolves cutting wires on your engine harness, proceed at your own risk.)

1. Unplug the connector off your engine coolant sensor, it is located on top of the engine in the very front of it, it is a 2 wire connector.
2. Cut the tan wire with the black strip in the area of the plug, leaving enough wire to connect pieces to it, and to reconnect to itself if you ever have to.
3. Take a piece of wire butt connect/solder which ever one you prefer, to end of the tan wire that runs into the main wire harness, run this to your switch that you have mounted in your desired position and connect it to the center terminal on the switch.
4. Take another piece of wire and connect to the other end of the tan wire, the one going to the sensor plug, run this wire to your switch and connect to either of the remaining two terminals on the switch.
5. Splice another peice of wire in the red wire with the white stripe on your coolant sensor harness, run this wire to your switch. Connect the resistor to the end of this wire, and then connect it to the last terminal on the switch. Make sure to tape up the resistor, and protect this wire so it doesnt short out on anything.
6. Plug the harness back into the coolant sensor.
7. Start your engine and flip the switch, enjoy your manual high idle. The switch allows you to turn the high idle on, or let the sensor work normally. Note: This will cause your temperature gauge to read incorrectly while you are in high idle mode. This did not set any codes on my engine.

 

Nice work. So you just trick the engine into thinking it's cold and it will idle up to 1000rpm?

 

You sure it doesn't set any codes? The ecm also uses the temp reading from the air intake sensor for the high idle. Looking forward to your diagram.

 

All it is doing it make the engine think the coolant is colder than it is, which causes it to jump up 1000RPMs.

I tested it this morning and let it run in high idle for about 5 minutes and it never set a code, only time it set a code was when I completly disconnected the sensor.

 

Sounds great! I'll have to try it on my 03! I could use hight idle in the summer to cool down the inside of my truck! Hummmm? I'll try it and report back!

 

Image is now up.

 

I'm about to head out to the garage to change oil. Going to try the ground disconnect.

MikeyB

 

Let me know how that works for you Mikey, all it did for me was set a engine code, as it disconnects the sensor and cause the temp to read way over 250.

 

Tried it but my test leads are too large to fit into the connector housing. Will find smaller ones at work and try again.

MikeyB

 

Use a paper clip to stick in the connector and attach the leads to it.