700r4 transmission compatible with 96 engine harness?

melothegoat · April 12, 2019

I recently put a new engine in my handme down 92 Sierra 1500. The "new" engine is from a 96 Tahoe which is an issue because the tahoe had a 4l60e. The engine harness is from the 96 so the connectors that go to the transmission are useless since the sierra has a 700r4. I want to know can this engine and transmission work properly together even. Also can the 700r4 tv cable work with the new vortec tbi. thanks for your time

Mikebtte · April 12, 2019

They changed the connector in 93 when they went to the 4L60 transmission. 700R4 is similar but not electric. You will need a Newer ECM to control the newer transmission.

You can make a 700R4 work with the Vortec but you will need to find an ECM from a manual transmission or program out the Auto Transmission setting.

You could also use your old TBI stuff on a vortec block, you would have to buy the TBI to vortec intake and everything would bolt up. Was the old engine 305 or 350 and is the new engine a 305 or 350?

melothegoat · April 12, 2019

1 hour ago, Mikebtte said:

They changed the connector in 93 when they went to the 4L60 transmission. 700R4 is similar but not electric. You will need a Newer ECM to control the newer transmission.

You can make a 700R4 work with the Vortec but you will need to find an ECM from a manual transmission or program out the Auto Transmission setting.

You could also use your old TBI stuff on a vortec block, you would have to buy the TBI to vortec intake and everything would bolt up. Was the old engine 305 or 350 and is the new engine a 305 or 350?

Thanks for the reply. The original engine was a 4.3l v6 the bolt patterns match so that's not a problem. The new engine is a 350. Why would I need to get a different ECM ? I got the one from the Tahoe would that not work. Also the transmission I want to use is the original 700R4.

Mikebtte · April 12, 2019

I was not aware you had the ECM from the 96, that would be the best. You can use the wiring and all from the 96. The 92 ECMs are different.

You could swap the EPROM to a manual transmission if needed. That will let it know what is going on with the shifting.

melothegoat · April 13, 2019

1 hour ago, Mikebtte said:

I was not aware you had the ECM from the 96, that would be the best. You can use the wiring and all from the 96. The 92 ECMs are different.

You could swap the EPROM to a manual transmission if needed. That will let it know what is going on with the shifting.

Thanks but the problem about the wiring harness I have right now is that it has the green transmission connector and the transmission is non electric so I can’t connect it. Will this effect the engine or transmission if that connection isn’t connected?

Mikebtte · April 13, 2019

That ecm gets all its speed data from the VSS on the transmission. So if you plan on using it ECM for speed info you will have to look into other speed sensor options. May be able to tie into the 700r4 sensor some how. I'll have to look up that info, it's been a while

melothegoat · April 13, 2019

12 minutes ago, Mikebtte said:

That ecm gets all its speed data from the VSS on the transmission. So if you plan on using it ECM for speed info you will have to look into other speed sensor options. May be able to tie into the 700r4 sensor some how. I'll have to look up that info, it's been a while

If you do look it up it would be very helpful and I’d appreciate it. Will the TV cable work with the newer vortec tbi setup since the vortec had cruise control instead of the tv cable to the transmission?