Question about Tow/Haul Mode & Fast Idle

[jelag]

So I'm wondering if there is a pin on the ECM that switches when the tow haul button is pressed? I'd like to wire in a electric fan with a relay to come on when the tow/haul switch is pressed.... of course this can be either a "to ground signal" or a "+12vdc" signal to power a relay.....

Is there still a fast idle ability on these engines... and if so how do you invoke that feature...

Thanks guys..

 

[SnoKing]

Idle-Up Feature — Automatic Transmission Only
The driver-controlled high idle speed feature will help
increase cylinder temperatures and provide additional
cab heat, however, excessive idling may still cause the
exhaust aftertreatment system to not properly regenerate.
Extended periods of idle time should be avoided.
The Idle-Up feature uses the speed control switches to
increase engine idle speed and quickly warm the vehicle’s
interior.
1. With the transmission in PARK, the parking brake
applied, and the engine running, press the speed
control switch to the ON position, then press the SET
switch.
2. The engine RPM will go up to 1100 RPM. To increase
the RPM, press and hold the ACCEL/RESUME switch
and the idle speed will increase to approximately 1500
RPM. To decrease the RPM, press and hold the DECEL
switch and the idle speed will decrease to approximately
1100 RPM.
3. To cancel the Idle–Up feature, either press the CANCEL
switch, press the ON/OFF switch, or press the
brake pedal.

 

[SnoKing]

So I'm wondering if there is a pin on the ECM that switches when the tow haul button is pressed? I'd like to wire in a electric fan with a relay to come on when the tow/haul switch is pressed.... of course this can be either a "to ground signal" or a "+12vdc" signal to power a relay.....


Thanks guys..

What is the fan for? SNOKING

 

[jelag]

Snoking.... I'm a little worried about the temperature of the transmission as I pull my 5er across the mountains here in the Pacific Northwest... I have 2 choices 1) wire in a thermo switch in the oil line to start an aux fan.... or 2) see if there is a location on the ECM plug that might do the same thing..

As a former PacBrake distributor I'm aware of several ports on the ECM for other items... like the connections to allow the ECM turn on/off the exhaust brake.... etc... We know the ECM sends the dash information to the gauges... so it just seems natural that they might have the same port/connection on the ECM....

BTW - thanks for the info on setting the fast idle...

 

[SnoKing]

Snoking.... I'm a little worried about the temperature of the transmission as I pull my 5er across the mountains here in the Pacific Northwest... I have 2 choices 1) wire in a thermo switch in the oil line to start an aux fan.... or 2) see if there is a location on the ECM plug that might do the same thing..

As a former PacBrake distributor I'm aware of several ports on the ECM for other items... like the connections to allow the ECM turn on/off the exhaust brake.... etc... We know the ECM sends the dash information to the gauges... so it just seems natural that they might have the same port/connection on the ECM....

BTW - thanks for the info on setting the fast idle...

I think most here will say that you are worried about a non issue.

 

[sag2]

The factory fan on your truck will pull twice as much air than any aftermarket fan you can buy, even if you add the electric to the OEM.

 

[Jim W]

Install a AL Mag-Hytec pan and a temp probe in the pan with gage. I have a 2500, 2008 Mega Cab with the 68RFE and 3:73 gearing with 17" tires pulling a 34RL Cedar Creek. I have weighed this combination and I am below 21,000 LBS, but not by much. Last year we cross the Rockies going through the Eisenhower Tunnel on I70 traveling to UT. The trans mission temps never exceeded 190F. So I would not worry with a fourth gen truck pulling a 5er.

 

[EDankievitch]

There was a thread on here many years back about adding the Idle up feature on a manual transmission truck. I think you had to find a lead under the dash and add a switch or add it to the Emergency Break switch so the PCM would get the signal and allow Idle up to activate.

 

[jhenderson]

Fast idle is achieved by enabling the cruise then controlled with the resume / accelerate button. There was a pin in the ECM for fast idle on a manual truck that had to be put to permanent ground not to provide 12 volts to enable high idle.

 

[shorthorn]

how big of a 5er are you looking to pull? I would think as long as you are within your tow ratings and drive reasonably that there would be no need for additional cooling.

 

[Tinman]

I can't speak to 4th gen, but on my 06 there is a pin out on the ecm for the exhaust brake circuit. I don't need exhaust brake, but I did ground out the circuit with a switch which basically puts it in tow/haul mode and, most importantly, keep the torque convertor locked to 30mph in drive. I think it's pretty handy. I posted thread about it years ago.