lt1 swap question
Thread Starter
Pro
Joined: Jun 2002
Posts: 662
Likes: 2
From: chatam nj
lt1 swap question
I have a 94 lt1 with wireharness(was mounted to a 6spd). I'm mounting it to 700r4. Question is, can I reuse the engine wireharness as a standalone since I'm mounting the motor to a 700r4? I'm hoping to not have to buy a wire harness to run the lt1.
Last edited by silvvette; Sep 21, 2015 at 06:58 AM.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
A TH700R4 will work all by itself but to control the lockup you'll need a pressure switch screwed into the 4th servo pressure tap and a 12-volt power source.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
Yes, you can. It will require some clean-up and re-working but it's possible.
You might be able to use the TCC lockup in the PCM by turning off most of the transmission diagnostics, but I'm not positive if it'd work or not. In older applications, the 700R4 used a feedback switch into the PCM so the PCM knew if it was in 3rd or 4th gear. But, the LT1 PCM knows the gear the 4L60e is in because it's in control of the transmission.
I would highly recommend switching to a 4L60e when you're so close. The electronic control gives much more precise control over the shifting and TCC lockup and it's easy to adjust the shift pattern or TCC lockup pattern when you don't like how it's working.
You might be able to use the TCC lockup in the PCM by turning off most of the transmission diagnostics, but I'm not positive if it'd work or not. In older applications, the 700R4 used a feedback switch into the PCM so the PCM knew if it was in 3rd or 4th gear. But, the LT1 PCM knows the gear the 4L60e is in because it's in control of the transmission.
I would highly recommend switching to a 4L60e when you're so close. The electronic control gives much more precise control over the shifting and TCC lockup and it's easy to adjust the shift pattern or TCC lockup pattern when you don't like how it's working.
Thread Starter
Pro
Joined: Jun 2002
Posts: 662
Likes: 2
From: chatam nj
Yes, I have the lockup completed. I wouldn't switch out the trans (yet unless I came across a 6spd) the 700r4 is rebuilt with about 5miles on it.
What 'cleanup' do you need to do to the harness? Is there a doc or a website that has a writeup on what steps to take?
What 'cleanup' do you need to do to the harness? Is there a doc or a website that has a writeup on what steps to take?
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
The harness has extra wires in it you don't need. You may also have to lengthen or shorten some wires so the harness will route how you want it to. Then, you have to add-in a fuel pump relay and some fuses for the power circuits. You may also want to add some relays for the switched EFI power so it's not running off the stock car harness.
Did you get a B, F or Y body harness? The B body has the PCM at the front and it's a pain to hide it.
Did you get a B, F or Y body harness? The B body has the PCM at the front and it's a pain to hide it.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
The 700 has a 4 pin square plug on the side skirt, one of the wires into it, is Red...that goes to a relay wired to the brake switch, use the stock switch, I had odd malfunctions traced to the damn aftermarket brake switch that opened another set of contacts....just get a 12 volt relay and open set of contacts removes 12 from the trans, unlocking the converter, no matter what when the brakes lights come on....yes the lockup is controlled by a 4th gear pressure switch, could even add a 3rd gear pressure switch if you want.....they ground the other end of the coil allowing pressure to the TCC......
As for the LT1 I have a highly modified LT1 induction on top of my L98 engine, and retained the HEI in back.....see pix at my site below.....
the intake is now RED, old pix.....
As for the LT1 I have a highly modified LT1 induction on top of my L98 engine, and retained the HEI in back.....see pix at my site below.....
the intake is now RED, old pix.....
Thread Starter
Pro
Joined: Jun 2002
Posts: 662
Likes: 2
From: chatam nj
Everything I have(harness, ecm, acc, motor etc) is a complete pullout from a 94 c4.
So, once I install the motor and a tach to the 700r4, I can reconnect the stock wireharness to the stock motor parts (accessories, sensors, option etc), the fine the power line from the harness (ground wire would also be attached) and connect to the c3 engine harness, and it should work?
I'm not concerned about the fuel pump or ecm positioning.
So, once I install the motor and a tach to the 700r4, I can reconnect the stock wireharness to the stock motor parts (accessories, sensors, option etc), the fine the power line from the harness (ground wire would also be attached) and connect to the c3 engine harness, and it should work?
I'm not concerned about the fuel pump or ecm positioning.
