Lock-up Mod

[M.L.S.C.]

The IDI neither needs nor uses any input from the PCM to start and run, so I believe your no-start condition is caused by a bad contact in the engine harness - check those connectors inside the engine on the driver-side of the firewall, maybe you knocked something loose accidentally?

The other problem is caused by the PCM entering "limp-home" mode, essentially if you throw the switch on and lock the converter whenever the PCM commands it to be open this will be interpreted as an electrical failure and the PCM will switch to failure-management aka "limp-home" mode and you will only have 2nd and 4th unlocked. It's a hit or miss deal, some trucks don't do this but many do, so I guess that makes your situation sorta part of the norm. To avoid this when you want to manually control the lockup you need to have the PCM connection severed from the lockup solenoid harness and you need to feed the PCM a "dummy" signal. Stay tuned for a wiring diagram for this...

[chuckster57]

For the wiring diagram. My tranny is doing okay for now, lower temps and lower hills help.

[cre8ive]

WOWWWWWWWWW!!!!

Trying to find a single point failure that could cause these problems. After sleeping it over, decided it had to be one of the trans connectors. Got up this morning and reseated both connectors and went out for a drive....WOWWWWWWWWW!!!! This is how life should have been all along.

1. Trans shifted better than new.
2. Worked great with and without the GV Over/Under engaged.
3. Light comes on every time TC locks, automatically or manually with the switch.
4. TC Locks automatically at 10 mph on acceleration from stop.
5. Love, Love, Love the torque.
6. Engine was extremely cool (Below 'N' on gauge)
7. Trans ran extremely cool 140-150 degrees!

Can't wait to get 'er loaded up and see how she does on the next trip!

The only possible drawback I can see is the light (LED) stays on dimly when the key is off. It shouldn't draw enough current to drain the battery, but I'll monitor it over the next few days to see. If it does, I guess I'll disconnect that part of the mod, bit it's nice to be able to see when the TC is locked or unlocked both manually and automatically.

Thanks to everyone for their help... I still love my truck, even when she's not doing what she's supposed to.

Kevin

[Snotzalot]

>Got up this morning and reseated both connectors and went out for a drive..

I keep telling folks, pull the plugs and reinstall and all will be good. No one ever listens......

[Fozz]

It's a great mod! I just got back from a 400 mile trip, trans worked great. Never got above 200 (but I have two coolers up front), even on some hard pulls. I think I might have been close to Chuckster territory (central CA)? Paso Robles . A couple of long hard pulls on the northbound 101. Was nice having the engine braking coming back home. I also put in some lights, a red light when locked-up and a green light when 'normal'.

[M.L.S.C.]

A few days later, but I've been pretty busy here, so sorry for the delays:



When you cut the purple/yellow wire and extend it to the cab the end that comes from the transmission is marked in red in my diagram, and the end that goes to the PCM is in blue. Parts in gray are optional - red LED will light up when converter locks up, green LED comes on when you switch to factory PCM control.

[chuckster57]

Originally Posted by Fozz

It's a great mod! I just got back from a 400 mile trip, trans worked great. Never got above 200 (but I have two coolers up front), even on some hard pulls. I think I might have been close to Chuckster territory (central CA)? Paso Robles . A couple of long hard pulls on the northbound 101. Was nice having the engine braking coming back home. I also put in some lights, a red light when locked-up and a green light when 'normal'.

You were a little south of my area. I am up closer to Stockton/Sacramento.

M.L.S.C. Looks like I might do this mod when I get home and have access to my tools and stores that I know will have the stuff I need. A few posts back you said that I could just tap into the purple/yellow wire, but it might cause issues. I have decided that the other side of the country is not the place to find out the PCM puts it in limp mode, Thanks again for all your help.

[cre8ive]

I understand all of your drawing except the 'Green 12v to ground'.... shouldn't it be just 'to ground'?

[M.L.S.C.]

Yeah, it's a ground wire, I just labeled it "12V to ground" since that's a pic of the switch wiring and you gonna measure 12V at its terminal. Just run it to a good ground and you'll be fine. I highly suggest the switch be mounted on the shifter, makes the whole converter <-> OD button shuffle a whole lot easier