Paz8 Posted October 22, 2006 Share Posted October 22, 2006 Running a 700r4 in my ZX, just got it on the road, before installing the trans I modified the lock-up TC to single wire operation were it will lock up in OD only. My question is this, by using the fourth gear pressure switch to lock the TC does it lock up at the same time the trans shifts into OD? I drove Camaro"s years ago and seem to remember that the trans would shift into fourth gear and then I could feel the TC lock up after that. I know that the single wire mod is working because the first time it tried to lock up it blew a 10 amp fuse, I just can't feel it lock up. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 23, 2006 Share Posted October 23, 2006 Blew a fuse, uh? How do you have it wired? assume you are not using the ECM. The pressure switch is putting out a ground signal and the LU solenoid needs 12V. Only way I see that working is through a relay by running and splitting the 12V to the 30 and 86 relay terminals, running the 87 relay terminal to the LU solenoid and the ground from the pressure switch to the 85, using it as a trigger. What you are missing is the capability to unlock the converter but stay in 4th for a mild "downshift" when cruising rather that a downshift that is more than a normal 4-3. You also might end up lugging the engine if the 3-4 is done at a low RPM. Quote Link to comment Share on other sites More sharing options...
Paz8 Posted October 23, 2006 Author Share Posted October 23, 2006 No computer, installed a new N.O. 4th gear pressure switch (grounding type), +12-V runs through brake pedal switch, not brake light sw, seperate sw, to lockup sol. and then to pressure switch. Trans sat around for a while and I think the sol. may have been a little sluggish to blow fuse first time, had no fuse problems since. I installed BM shift kit and TV valve in the trans also, trans works perfect nice and crisp shifts. Still doesn't answer my ? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 23, 2006 Share Posted October 23, 2006 No computer, installed a new N.O. 4th gear pressure switch (grounding type), +12-V runs through brake pedal switch, not brake light sw, seperate sw, to lockup sol. and then to pressure switch. Hope I am not misreading what you are saying but here is how I interpret what you wrote. You are running 12V through a brake light switch, then to the LU solenoid and then to the pressure switch. If that is correct then you will blow a fuse every time you go into 4th because you are grounding the 12V source. As for your question, I guess I did not answer it directly. The ECM does not lock the converter exactly as the trans shifts into 4th because it uses more than just the 4th gear signal to determine when to LU. As a result, there are circumstances when you can unlock the converter and still stay in 4th when cruising. With your setup the LU will engage/disengage with 4th gear. Quote Link to comment Share on other sites More sharing options...
Paz8 Posted October 23, 2006 Author Share Posted October 23, 2006 Yea, the fourth gear pressure switch is self grounding, it's a simple series circuit, the LU sol has resistance, not a dead short to ground. The brake pedal sw opens the circuit when the TC is in lockup. I made my living for 30+ years by doing electrical/ electronics work, this is simple sh*t, no need to make it complicated. The trans is rewired at the valve body. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.