5.3 with TH400 harness questions.

Been building a harness for a 5.3 in a 1969 chevy shortwide the past few nights.
About to pin the connectors and have a few questions.

Owner is using a TH400 and will not be using a VSS. I've explained the issues with not using one and he'll add one later maybe but not now.

I figured I would simply program as a manual (I warned him of possible idle issues with this).
while repinning however I came across the CPP and got to thinking.

If it's programmed as a manual,it would not be able to control TCC lockup right?

The harness is hasn't been totally wrapped yet,so if I need to add something now is the time.

How has everyone else dealt with convertor lockup,programming,pinning etc.. for a TH400?
I know nothing of the TH400 at all,I have changed a few camaro's over to manual after they swapped but it was a quick program and never heard from again as I remember.

Unless it's a later TH400 with a lock up ther's notjing to worry about. If it is a later TH400 (TH400C if I'm not mistaken), then you will need to either add a VSS or go with a vacuum set-up to control the lock up.

i wouldn't do the conversion without a VSS, I wouldn't have given that option.

After I proved the internet wrong about running without VSS... I'd never do it again, not even on the old 7747 which is the easiest. Which usually get used in Off Roaders and rock crawler so no E trans or even TCC, but it does help stable idle which is something really needed it the off road case.. Just to many quirks and dual tables ETC... to tune out. ARG!

There is still the kick down which is electric off throttle usually at gas pedal. Dave W is the one to talk to about that. It does look for VSS or? For certain speed before it can be active? Not sure how to on newer OBDII stuff but here's some info on what he did with 16197427 PCM.

http://www.gearhead-efi.com/Fuel-Inj...With-Turbo-400

Mark just brought up a good point, what ECM are you using? You may HAVE to use a VSS so that the proper tables are being used while driving down the road.

I think one option to eliminate the VSS ('0411 PCM) would be to raise the Abuse Mode Enable RPM's to maximum, or ZERO out the Abuse Mode Disable Speed. Might be a good idea to raise the p/n rev limiter to maximum.

I'm confused about the TH400 having a lockup torque converter. I can't remember a make / model / year that the TH400 had a lockup torque converter. I've been thinking the TH400 needs a kick down / passing gear switch to change gears from 3rd gear to 2nd gear.

http://www.gearhead-efi.com/Fuel-Inj...ections!/page4 post 56 I shows how I installed an accelerator mounted kick down switch on an '8747 ECM to '7427 PCM upgrade.

Maybe I got this all wrong about a TH400 not having a lockup torque converter and needing a kick down switch??

dave w

Sorry, It just came to me, it was a TH350C, that had a lock up converter.

I might have been thinking of a switch pitch converter that I believe was available in the TH400.

I'm pretty sure a VSS will be added at a later date,I wasn't really consulted before this guy bought a crapton of parts.The 400 was thrown in last minute,I am putting VSS in the harness and will be keeping an eye out for the needed parts. But for the moment it won't be using it.
Also forgot to mention I'm using an 0411 and wiring/bin for 2001 5.3 with case ground sensors.
Haven't so much as turned on the computer yet other than that stuff.

I should clarify I was assuming the TH400 had a lockup convertor,I know nothing about them.
Here's how this project has been the past week.


I was called saturday to see if they could drop it off sunday and have everything ready for a show saturday.
As this stuff generally goes,they ended up dropping the truck off late wednesday night while I was gone looking at another truck that will be dropped off when that one is done.
Got home about midnight and didn't even look at it,thursday I pulled the harness from the back of the truck and started stripping it. Thursday night I start plugging stuff in to route the wiring and stuff ain't plugging in.
Keep in mind I've barely even walked around the truck or messed with it short of under the hood.
So friday I start looking for the missing injector harness and another correct harness to pull from. A buddy stops in with a complete 2005 model harness.
Now I was just told it was a 2001 5.3 with a 400 trans can you wire it by saturday for a show.
I knew it got to my shop late because they primed it to enter in the under construction category,but didn't think he would be driving.
Buddy and I start checking out the truck,and I began to realize how rough it was.
It had no transmission,no headers or exhaust,no headlights,taillights,driveshaft. No door handles,but actuators installed-no switches in sight. Original dash,guages,interior stuff with random wiring laying around. ZEX nitrous kit is in the bed,next to a fuel cell(not bolted) no fuel pump or lines in sight.
Cam box in the cab with .614/.617 lift,TB is 75mm,heads ports had work done,topend was 2004+ stuff imstead of 2001.
I could go on and on,but moral was it was the day before the show...
I asked him to stop by to answer some questions about locations of stuff and he thought he would be driving it the next day.


So,I broke it to him that without 5-6 experienced hands there was no way this truck was driving anywhere in the next 24hrs.
I also convinced him to let me do the rest of the wiring on the truck,mainly cause the idea of them hacking into my harness for the nitrous drove me nuts.


But I also now need to tune a damn cammed 5.3,I've really only ever done the easy stuff and there was no way I was tuning that cam in 1 day.
I'll be putting up a thread on that one by itself.


Anyway,that's what i'm dealing with.


I'll do some checking on the Th400 convertor,I'm still waiting on the tailshaft info from him so I can start checking sheds/shops for one that is compatible.
If it is the small shaft than I can use 4l60/700r4 stuff I understand,so hoping VSS won't even be an issue.
If it doesn't have TCC than that would be gravy right now to not worry about.


Thanks guys.