12200411 PCM swap for 1996 to 2000 GMT400 trucks

[EmeraldGreenVortec]

3rd Coast Z,
I'm getting my 0411 kit from Lextech soon, he put in tow/haul mode and included the wiring necessary. Would you mind explaining how you wired up your momentary switch to activate tow/haul mode?

 

[3rd Coast Z]

3rd Coast Z,
I'm getting my 0411 kit from Lextech soon, he put in tow/haul mode and included the wiring necessary. Would you mind explaining how you wired up your momentary switch to activate tow/haul mode?

I just ran the wire from the pcm through the firewall behind the dash. The momentary switch is the square one. It has two prongs on the back, one is for the wire from pcm and the other I just grounded to the framework behind the dash. It's really a straight forward install. I just took my drimmel and cut out the hole in one of my blank accessory panels.

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The momentary switch is just a spring loaded switch that doesn't stay "ON". It doesn't have to be anything special, this one came from a local electronics parts outlet.

 

[rmoreaux1]

I wired up my pcm last night and it fired right up. The crank re learn code came up immediately and this morning I wired up the trans wires even though the spreadsheet did not list them. I don't know if they are no longer needed but I pulled up all data and found the corresponding pins and pinned them anyway. The crank re learn did not go as planned. The truck was acting all weird and didn't want to rev up. It drove ok when going over to my buddy's shop but his scan tool had trouble performing the re learn. We tried it several times and each time it didn't want to work. We decided to do the relearn with HP tuners and every single line in the scan tool was greyed out. We recently upgraded to the beta release so we can tune my Camaro and it seems that the scan tool function is acting up. We tried again with his scan tool and after a few tries everything it finished the relearn. I currently have no engine codes but the truck doesn't like the starter tune at all. I am new to tuning and will be buying my own hp tuner outfit. The idle is super low and the fuel trims are pretty rich at idle also. The fueling in cruise is ok, not ideal but will work until my software comes in. All in all the swap is super easy. The only issue is the crank relearn took a few tries to make it work.

 

[Lextech]

I use that same tune on all of the 7.4s and they seem to run fine. Did you follow the EGR instructions?

 

[rmoreaux1]

Lextech, I did not do anything with the EGR except unhook the plug at the valve. I thought with the EGR function deleted in the tune that was all that was needed until I remove the EGR completely and install a block off plate, am I wrong on that one.

 

[Lextech]

The 0411 operates the EGR differently than the 96/97 trucks. Regardless of the tune, if the EGR valve is installed, it needs to be wired as per the instructions. The condition you are describing sounds like that issue.

Jeff

 

[GordonCustoms]

http://www.gmt400.com/forum/showthread.php?27572-0411-pcm&highlight=0411
In this thread I explaine how I modify and use a shift lever out of a Gmt800 with the tow / haul button on it and the PAC TR-7 module to get a light to come on and stay on with the push of the momentary ground button on the shift lever

 

[GordonCustoms]

Here's the finished tow/ haul light in my truck

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[Trav_69Stang]

Here's the finished tow/ haul light in my truck

I like how you did this. I went a different route and used a push button out if an express van the only thing I wish I had was an indicator light

 

[EmeraldGreenVortec]

completed the swap last night in about 2 hours taking my time. The truck runs great, idles great. Although this morning it threw a P0405 code for a low circuit on the EGR. I verified the correct wire position C2 pin 7 and spliced into the connector end of the pink EGR connector wire like the pin out sheet specified. Anyone ever had this problem?