I just installed my 700-R4 about 3 months ago and ever since, my lockup has never worked properly. My biggest problem is that I'll be driving down the road and it locks up fine but the second I step off the gas it kicks out of lockup and when I step on the gas again, it kicks in again. That's WITHOUT touching the brake pedal at all. I know there are 3 wires on the lockup.. the dark green wire goes to the ECM, the tan/blk wire is a ground, and the purple wire goes to the brake switch and in turn goes to the fuse box. I understand that the lockup is supposed to kick off when you hit the brake, but my kicks off when I let off the gas, without touching the brake. I was thinking that maybe I hooked the connector up wrong into the transmission but I haven't had a chance to check it. My car originally had the 700-R4 and I swapped to the 350 turbo which doesn't use lockup and had that in my car for 2 years so I can't remember how the lockup connector is supposed to hook up. Anyone with ideas, opinions, things to check.. anything would be helpful. Thanks!

------------------
1986 Trans AM
305 TPI
Well over 200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear (2.77's....oh joy) :P
Completely Stock
Current Project: upgrade to a 355 TPI, 6" rods, 9.7:1 Compression, Stock TPI ported, 24#/hr LTI injectors (cleaned and flowmatched), Hedman Shorty Headers, 3" cat back exhaust with flowmater, SBC 993 heads completely redone and modified for 1.6 RR, Comp Cams XE262-14 TPI Cam, Ed Wright Fast Chip, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Box, Hypertech hot coil!!

[This message has been edited by 86TpiTransAm (edited September 06, 2001).]

 

I think it's supposed to unlock when you back all the way off the gas. All the cars I've driven with lock up TC's do it. It has something to do with lowering RPMs while coasting. I think it's annoying as hell.

 

Sounds normal to me. At high vacuum(no engine load) and low vacuum(fairly loaded engine) it unlocks. If you don't like it, make a manual switch.


------------------
350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro


[This message has been edited by 82camaro (edited September 07, 2001).]

 

Yeah.. it is annoying as ****. I don't like it a bit. I heard that it's supposed to "cycle" in and out like that but I sure as hell don't remember my first 700R4 doing that. And I've also had a few people tell me that it's NOT normal and that the only time the lockup should kick off is when you hit the brake (hence the reason the purple wire from the lockup goes to the brake switch). Another thing really annoying is that my lockup kicks in TOO soon and I have the detent cable and everything properly adjusted. I plan on fixing that with a switch wired into the Dark Green ECM wire so that when the switch is off the ECM can't tell the lockup to kick in. It shouldn't cause an SES light either because I had the lockup completely unhooked, for obvious reasons, when I had the 350 turbo in there and never got an SES light.

------------------
1986 Trans AM
305 TPI
Well over 200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear (2.77's....oh joy) :P
Completely Stock
Current Project: upgrade to a 355 TPI, 6" rods, 9.7:1 Compression, Stock TPI ported, 24#/hr LTI injectors (cleaned and flowmatched), Hedman Shorty Headers, 3" cat back exhaust with flowmater, SBC 993 heads completely redone and modified for 1.6 RR, Comp Cams XE262-14 TPI Cam, Ed Wright Fast Chip, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Box, Hypertech hot coil!!

 

The PROM is programmed to unlock the converter at a specific TPS% threshold(rate of throttle position change in a pre-determined amount of time), at a specific road speed when decelerating, and accelerating. There is also a constant, in MPH, for when to lock and unlock the converter in high and low gears. For example:

TCC Unlock speed(Low Gears): 27 MPH
TCC Lock Speed(Low Gears): 28 MPH

This would mean that in 2nd or 3rd gear, as soon as you go over 28 MPH, the converter locks, and will stay locked until you go over the TPS% threshold of unlocking(programmed in the PROM), if the coolant temperature falls below the minimum enable temperature, if you go into high gear, or if you go under 27 MPH. The same applies for high gear, or Overdrive as most call it.

[This message has been edited by MJT (edited September 07, 2001).]

 

Now that's the best explanation so far. That makes perfect sense and explains exactly why mine kicks in and out like that. My VSS is not "functioning" right now so the ECM has no idea what speed I'm going. Question is... if the ECM uses speed to determine when to make the TC lockup and the ECM has no clue how fast I'm going, then how does my TC lockup work at all???

 

Yes that is an excellent explanation. If your VSS isn't working it shouldn't allow the TCC to work so I suspect you are saying that the speedo doesn't work and are assuming that the VSS isn't too right? Or are you saying that you watched with a scanner and saw no speed changes?

[This message has been edited by transfixleo (edited September 08, 2001).]

 

What I'm sayin' is that the driven gear that's supposed to be in the transmission and connected to the VSS is NOT THERE .... at all. The new tranny has the wrong drive gear and I couldn't get my driven gear to fit in there with it so I just put the VSS in the tranny without the driven gear until I get chance to buy the gears I need from GM and get the time to put them in. So basically, the VSS has no way of sending the speed to the ECM ... but the lockup still works.

 

I must have something wrong with my tranny then cause, when I programmed my PROM, I bumped the lockup around 40mph or something for 3rd & 4th gears. I do not think my car goes out of TCC until I slow past 37 mph. I can feel it release.

I might be wrong though. I will have to check next time I go for a spin.

JOhn

------------------
87 Formula Yellow/Black

5.1 TPI Automatic
Baer 12" brakes 4 wheels, KYB AGX Adjustable Shocks & struts, Custom Leather interior, WAAAY TOO MANY MODS TO LIST

87 Formula TPI (5 Speed) Yellow/Gray STOCK

1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)

83 Camaro (Parts)
83 T/A (parts)

http://www.3rdgenformula.com