BackInBlack86

i'm putting a '94 Caprice LT1 into my '92 C1500 shortbed. i have pretty much decided that i'm going to wire it myself. which would be better? integrating the LT1 harness into the stock C1500 wiring, or converting my stock LT1 harness to stand alone, and eliminating what i do not need of the stock TBI harness. is it worth the trouble to run the 4L60E with the LT1, or should i just stick with my 700R4 thats currently in the truck and use the 93 LT1 throttle cable bracket?

92rs85berlintta

iTrader: (1)

all you need to do pretty much is run power wires to the lt harness. I made a plug in and go for my 92 and it really was a waste of my time.

dbrunner2

Well, more than that...it'll need a vehicle speed sensor input from the tranny, VSS output to the dash, tach output, neutral safety switch, service engine light, relays for fuel pump, cooling fan, and smog pump, and VATS module input (I think I remembered everything...not sure, since I mated my LT1 to a T5, so there will be a few differences, plus it's been a few months).

I would recommend going with the 4L60E if possible, since it'll have the correct 40-tooth reluctor wheel and pickup for the VSS signal the computer needs (this can be a BIG pain in the neck to provide...I speak from experience here). Also, you won't need to reflash the PCM to explain to it that it no longer has an electronic automatic behind it.

BackInBlack86

no need for a smog pump, since the smog ***** arent in this area. will the VSS output of the 4L60E work with my existing speedo? the tach output is just for the ECM correct?

SES light i can make work with a regular indicator light, if not able to hook it to the existing light in the cluster. fuel pump and fan relays were a given.

BackInBlack86

also, i wont need to reflash my ECM to run a "manual trans", because i dont have an ECM. someone scabbed it from the car before i got to it. since i'm going to have to buy one anyways, i could just as easily but one for a manual trans car.

dbrunner2

The tach output is for the gauge cluster. As for the speedo, you connect the PCM to the VSS installed in the trans tailhousing, it interprets the 40-pulse-per-driveshaft-revolution signal, and generates a signal that the stock speedo can use (2000 pulses per mile I believe). This is assuming that the truck has an electric speedometer; if it's cable drive, things get much more complicated. It would probably be easier to put an electric speedo in than make things work with the cable drive.

92rs85berlintta

iTrader: (1)

For the speedo you dont need to have the vss hooked up to the lt1 pcm. I dont have mine hooked up and It will not make any difference in how it runs. If its cable leave it. If its electronic leave your stock ecm in the vehicle hooked up and it will be fine. Since the pcm will be under the hood theres no sence ripping the old one out and changing tail shaft speedo rings when the stock ecm still will work to tell you your speed. run your ses wire to your ses light get the pcm reprogrammed to remove the vats and it will be fine. Its really not the complicated.

Firebat

iTrader: (7)

The 4l60e vss and reluctor, if you use them with a 94-95 obdi LT1/700r4 combo will allow you to re-adjust the speedo just by reprogramming it. No need to change and figure out the speedo gears when changing the rear gears or have the speedo be off by changing sizes of the tires.

This is easy if you have a laptop and the tunercat program and the ability to program the pcm by yourself.

Otherwise might not be worth it.

dbrunner2

Provided you reflash the PCM to disable the electronic automatic option, the only things that will not work when it doesn't have a VSS input (that I can think of) are electric radiator fan shutoff at high speeds and the speed limiter (who needs it?). You can also disable the VSS diagnostic option so it doesn't throw a code and turn on the SES light.

Firebat

iTrader: (7)

My LT1-700R4 madz28.com tune has the automatic trans. option enabled. All the other things that could throw a tranny code are disabled though.

csmethie

ok so i just want to clarify from what i've read here. I'm planning to use a manual trans with my Lt1 and I want to keep my cable speedo. So i can eliminate the vss, and the only consequences would be the speed limiter is deleted,the coolant fan shut off at high speeds is deleted,and I will need to flash my ecu so i can disable the electronic trans,and to disable the vss diagnostic code.Please tell me if theres anything else to the best of your knowledge

Firebat

iTrader: (7)

I would recommend contacting a tuner, either madtuner or pcm4less and ask them just to make sure. I think that what you mentioned above is pretty much all of it though.