High Idle Install Question

[TLA]

Last night, I was hooking up my OD Lockout, and thought it was a really good time to hook up high idle and 2nd Alt. Uncovered ECM, unhooked C1 - Holy S??t - how do you get to the terminals? Any help would be much apreciated. I have checked all the old posts I can find.
Thanks, Tom

[dmaxster]

maybe this will help... smile.gif Here are some tips.....
Disclaimer, this was e-mailed to me from third party members. It could be incomplete.

Do it at your own risk!!
On the ECM (PCM) your looking at Connector C1 the only way to find this terminal is to take all of them off and hold the ECM up looking in the center of it for the letters (A, B, C, D)your going to install a terminal-w/wire (GM#12084913) in socket #71, run that wire through the firewall to a toggle switch (Plain On/Off toggle is fine).. Place the toggle switch wherever you like.. Then you run another wire from ignition power back to the toggle switch..

Start truck up, turn toggle switch on will get you 870Rpm
hit the Set switch on the cruise will give you 1250rpm
hit the Resume button will give you 1800rpm..

** NOTE: If switch is left on while driving Poor drivability will result..***

I haven't done the work yet.. I did have a few minutes last night to asess how and what needed to be done.. I removed the TCM (Wires still attached) then removed the cover over the ECM and rotated the ECM so I could see what was what.. It's not that dificult to do, but PLEASE if you have any fears don't attempt it yourself.. Have a Professional do it..

THE MANUAL STATES TO DISCONNECT THE BATTERY BEFORE DOING ANY WORK ON THE ECM!!!!
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Found the ECM after looking through the Helms manuals for about 30 minutes. For those of us who are DMAX challenged, the ECM is located at the front of the engine compartment on the driver's side (DS), just to the left of the battery and lower than the battery (left/right defined as standing in front of the truck and looking into the engine bay).

The black plastic cover comes off by releasing two tabs, one near the top edge of the cover located rearward, and the second is on the front lower edge which is hard to get to (and see). I released the top rearward tab first by reaching between the battery and the radiator hose, and pressing very hard. The front lower tab then released easily. The ECM plastic cover is a tight fit, but will come out with some slight bending. There was one plastic wire loom clip attached to the cover which needs to be released so the cover can be removed.

You will then be able to see the two 80 pin connectors. The BLUE connector faces the passenger side (PS) of the truck (BLUE is marked on that side of the ECM). The connectors themselves ARE NOT BLUE or RED in color - at least on my truck. There is a small RED area on the top of the DS connector, so I assume this is the RED one. I could not see the other end of the PS connector to verify a BLUE mark on it - but as stated above the ECM case is marked BLUE on that side.

There is a small bolt in the middle of each of the connectors which appears to hold the connectors to the ECM.

I did not go any further at this point since I do not yet have the proper terminal (GM part #12084913 from previous posts).

Can anyone clarify what "ignition power" means? I am assuming it means a source of 12V with the key "ON", but would like to confirm that before making an expensive mistake.

Throughout the Helm's manuals it would appear that the term PCM is used on the gassers, and ECM for the DMAX - , and this may cause some confusion. Please correct me if I am wrong on this.

ON EDIT: The BLUE connector should be the ECM C1 connector, the one to add the terminal/wire at position 71.

Guys this fast idle thing is easy. No need to wait on an "Offcial" article. Just buy the little terminal from GM, a SPST toggle switch, about 20' of 18ga wire, some dielectic grease, terminals to attach the wires to the switch (I use switches with screw terminals, but whatever floats your boat) and a way to get the +12 vdc ignition power to the switch (I used a T-Tap and a Spade terminal and found 12 vdc ignition power in the power distribution center under the dash on the DS).

1)DISCONNECT BOTH BATTERIES!

2) Take your GM terminal and attach enough 18ga wire to reach the location where you plan to mount your switch. Be sure this connection doesn't have excess solder because it will not fit in the hole if it does.

3) Remove the TCM from the radiator's plastic shroud and set it aside.

4) Remove the cover from the ECM. It has two plastic tabs holding it on, just pull the cover away from these tabs and it will come off. You will have to remove two wire clamps from the cover in order to get it out of the way.

5) Unhook the metal clip holding the ECM in. It just pops off. Then push the two plastic tabs that hold the ECM up and push it out. The ECM should now be loose.

6) Manipulate the wiring so you can turn the ECM with the wires facing up. Their should be two groups of wires. In between these two groups on the ECM's casting their are letters and arrows pointing to 4 differnt sections on the ECM. Find C1. Remove the bolt securing the connections on the side that includes C1. (You must remove that entire side, You can not remove just section C1)

7) Grease the GM terminal with dielectric grease and insert it into position 71 on the C1 Connector. Push it far enough down and you will feel the lock engage. Pull back slightly to see if it's locked. (The rubber seal stays in, just poke some thing through it to make a hole for the terminal)

8) Reinstall the connectors on the ECM being careful to keep the connectors square with the ECM as you tighten the bolts to the correct torque as stated on the connectors.

9) Reinstall the ECM paying special attention to the routing of the wires so that you do not pinch them. Make sure it is secured in its plastic tabs as well as by the metal tab. Reinstall the cover, wire clamps, and TCM.

10) Take the new wire, covered in wire loom of course, and route it into the cab. (I cut a hole in the existing rubber grommet in the dash and routed it through there, but if you like to drill holes. . .)

11) Attach the wire from the ECM to one side of the SPST toggle switch. Attach a seperate length of wire to the other side of the toggle.

12) Mount the toggle in an appropriate place.

13) Find a +12 vdc ignition controlled circuit. (I used the pink wire in the "12-Way Vanity" connector in the underdash electrical distribution center. This connector is the one in the bottom left corner of the block) Connect the wire from the toggle to this circuit with a T-Tap and spade or other method. I also installed a 2 amp mini fuse and holder between the toggle and +12 vdc ignition power source.

14) Reconnect both batteries.

15) Do not wear the switch out playing with the new toy.

Idle= 670rpm

Fast Idle On, Cruise Switch "ON"= 800 rpm

Fast Idle On, Cruise Switch "ON", Press "SET"= 1200 rpm

Fast Idle On, Cruise Switch "ON", Slide Switch to "RESUME"= 1800 rpm.

If a) the brake pedal is depresses, or b) you put the gear selector anywhere but "P" or "N", or c) you turn the cruise control switch "OFF" the engine will return to normal idle.

#12084913 GM Micro Pack terminal

[AKDmax]

Hey Tom,
Just installed the high idle myself. You have to take that little gray plactic cover off the top of C1. It's pretty easy to get off once you flip the whole thing over and can get to it. Find 71, poke a hole through the yellow seal and then install your pin, ensuring it's completely installed and locked. Snap the cap back on and reinstall the works. Good luck...

On edit: Dmaxster, you beat me by seconds!! It's way easy to do this!! the hardest part is getting to C1 and installing the pin. Everything else is simple. I ran my wire through the large rubber seal on the firewall similar to the "got gauges" article... I used an "add a circuit" with 3 amp fuse instead of the fuse tap. Also used a lighted switch I picked up at Radio Shack and installed it next to my brake controller. Took the power from the IGN1 fuse in the panel. EASY!!!

[ 09-08-2002: Message edited by: AKDmax ]</p>

[TLA]

Thanks guys!!!!!! I knew it was easier that it appeared, but at the end of the day, I just quit before I screwed it up.
Thanks again,
Tom

[Flyboy]

Just a note about the large grommet that goes through the firewall. If you un-tape the end of it, you can push the wires through with the existing wires. No need to punch a hole in the grommet. I put the wires for my DG-211 gauge that way. Tape it back up when you are done.

[dmaxstu]

To feed wires through the big grommet on the firewall I used the smallest plastic rope splicing fob I could find at the local ACE hardware store, grease it up good, push it through alongside the existing wires. Have a helper hold the new wire inside the fob while you pull the fob the rest of the way through and voila the wire has passed thru the firewall. Stu

[TLA]

Thanks to you all for the help - it gave me all I needed to get the job done. Everything works as advertised, and the whole under hood hook up took only 30 minutes. 'Just hate to use the "if it don't fit, force it" technique.
My only regret about this site is that I didn't join before I bought my truck.
Thanks, Tom

[lbrown]

Hey Guys,
Just a point of interest.. Ive done the high idle on two trucks now and the '02s do not have the 800 idle. With cruise on and the switch on, you have to push the set button twice to engage the high idle at 1200 rpm. Pushing the resume gives you the 1800 rpm. Anyone else run into this?

[dmaxster]

yup you have to reprogram it.....Kennedy had done it for me.....so I don't know what all is involved but it didn't take him long....

Kennedy had his scan tool along and he hooked up for some "road dyno" runs, comparing his truck's parameters with Idle_chatter's. Initial runs were in stock mode, but then Kennedy gave us a hole shot with the dynomite turned on. We were IMPRESSED!! Kennedy was helping dmaxter with his high idle settings, and that's when we found out that the pto speed setting somehow overrides the governor on the engine. For a few brief moments we had a Dmax turning better than 4,000 rpm while parked in the driveway. That was also impressive, if a little scary.


What Nels referred to was while programming the fast idle. I did Dmaxster's and for some reason it didn't take the entire program. Since the defaults are 6375rpm, that's where it was heading! I cut it off when it was climbing in the red approaching 4k so really no biggee, but if left go, I'm pretty sure that's where it would settle...

:cool: dmaxster

[TLA]

Mine does work the same as lbrown's. I don't need the 800rpm, so it works OK for me.