i am posting this for a guy on pirate thread linky

Hey,

I'm in the final stages of swapping an LQ4 out of a 2007 Silverado 2500 into my old YJ. I have an NV4500 in it and so I had the computer re-programmed using whatever stock programming is used for a LQ4/NV4500 (minus VATS, Torque Mgt., etc.).

I've found a little difference in the physical wiring harness that has necessitated adding a wire to the PCM for the clutch position switch (that I'll have to install on the clutch pedal/linkage to get the cruise to work right). It's pin number 35, Gray Wire, circuit number 48, CPP Switch Signal (M/T) on C1 into the main PCM. (There wasn't a wire there because the donor truck was an AT, but there is now)

I have a couple of questions regarding this:

1. Is this a normally open switch that would connect the wire to +12V when the clutch gets pressed or a normally closed switch (like the TCC brake switch for the cruise control) that has +12V flowing through it all the time EXCEPT when the clutch is pressed?

2. Are there any other "gotchas" I'm missing when trying to get an A/T harness to function correctly with a manual transmission?


Thanks!
Jake

 

bump

 

The CPP has both a normally open circuit and a normally closed circuit in it. The normally closes circuit send 12v to the ECM at all times. As soon as you start to push the clutch, the normally closed ciruit opens removing the 12v from the ECM and disabling the cruise control. When the clutch is pressed all the way down, the normally open circuit is closed sending 12v to another pin on the ecm which will allow the vehicle to start.

 

thanks man

 

No problem

 

(I'm the guy who originally asked the question on the PBB)

Hmmmmmmmmm... Because of the plug it goes to (along with other cruise-related stuff), I'm guessing that the pin-out I found (pin number 35, Gray Wire, circuit number 48, CPP Switch Signal (M/T) on C1 at the main PCM) is the normally closed one that opens to tell the computer to kill the cruise when the clutch is pushed in and that some other (as-yet-unnamed) pin-out is used for the normally open starter interlock function...

Could the other one be the same pin-out that is used for the Neutral/Park starter interlock on the AT? Something different?


Thanks a lot for your help,
Jake Harsha

 

I would read through vanillagorilla t-56 swap thread. Not sure if its there tho?

link

 

Okay... been reading that thread closely and found this:

So if I'm reading this right, I had it backwards...I just have to run the TCC brake (normally closed) through both a switch at the brake and a switch the clutch as well (since it's normally closed breaking either one should release the Cruise Control) and leave the gray CPP clutch wire I discovered unhooked since I don't really care about preventing the Jeep from starting while in gear (it actually comes in quite handy at times to be able to do so).

Is this going to cause any driveability problems? (I'm thinking the PCM might return to idle more slowly to make sure it doesn't die when I push in the clutch suddenly under power or something like that...?)


Thanks,
Jake

 

I don't think so, I have the same setup (motor/trans) but from the factory, I take it offroad enough, and i've never had a any issues, but i don't have the clutch switch unhooked.

the factory starter is plenty strong enough to crank over what you have in 1st gear also, it moves my 6400lb truck without any issues.

What are you using for a clutch, and master/slave?

 

Clutch/pressure plate are out of a 2004 4.8/NV3500 truck. Not sure if this is true, but I was told that they use the same stock clutch and flywheel parts in the manual 4.8 as in the 6.0/NV4500. They said the 4.8 pieces are a damn sight easier to find (probably in better condition usually too) so that's why I went that route. Either way, I'm not too worried about it...any clutch sufficient to move a 5000-pound pickup should be fine in a little Jeep.

Clutch master cylinder is the stock 1987 Jeep Wrangler YJ. Bellhousing/Slave is 1992 3/4-ton Chevy (external slave)...same year as the transmission (6.34:1 granny low!).


Jake