Hey guys,
My Camaro will lock its torque converter only for a few seconds after taking off on a highway onramp, then the torque converter will unlock and never return to locking again, until I take off on another onramp where it will do the same thing. I have noticed that my torque converter locks in D, but not OD. Could this be a bad VSS (Vehicle Speed Sensor)? I notice I have no lockup upon directly starting my car, but this is normal as 122 degress is the minimum temp for lockup, correct? But once I get the engine warmed, it should lock up if I am going over 50 at less than half throttle, which I do alot and it does not lock. Another thing that lead me to believe my VSS is going bad is the fact that in the summer's heat in 2002 my car would run VERY HOT because the engine fan would not turn on (It did when the A/C was on though, so it DOES have power when it wants it). I read that the VSS controls the TCC lockup (which is not functioning properly), as well as my electric fan control (which is not functioning properly), as well as a few other things, and my idle is a little on the rough side if that helps. Forgot to mention the funny side to this story, my speedometer still functions as it should. Let me know what you think so I can jack this car up if needed and grab that defective VSS off the tail of my 700-R4, thanks.

 

If the ECM was not getting VSS signals, you would generate an error code after about five minutes of driving. That's not to say that teh VSS signals are correct, but if the speedo is working correctly, the pulse coder is probably fine. If anything, I'd be looking more at the VSS buffer circuit for the ECM.

 

AHA, so it was that P.O.S. borg warner ECM module, what a POS!!!! 100 bux

 

Oh, that's right. A '92 should have an integrated buffer, not a "strap on" module like my '86. Before you condemn the ECM, see if you can your hands get a data scanner/logger to read the VSS signal via the data port. It might save you some headaches.

 

Another thing you can do is test the load side of the ECM for the TCC. Connect a test light to a positive voltage source (the lighter or fuse panel are handy) and ground the test lamp to terminal 'F' of the ALDL.



The test lamp should be on any time the ECM commands the TCC to lock. If the lamp goes on but the clutch doesn't lock, you may have a problem with the TCC relay, TCC electrical connector at the transmission, or the TCC servo/valving/clutch plate itself. If the clutch locks and unlocks in sync with the test lamp, teh ECM is commanding it to release for some reason (brake switch, etc.)

 

Vader, your posts are always helpful. I'm having a similar problem, except my TC won't lockup at all. My speedo doesn't work either, but this method should tell me if the ECM is working correctly.

 

F-One,

Your car should have a VSS mounted to the tailshaft of the transmission. Pulses generated by the VSS are buffered and split, sent to the ECM, speedometer head, and cruise control unit. I'm guessing the cruise doesn't work, either.

I'd check the VSS for pulse output with a test lamp or analog meter. If you have a strong signal, inspect the connections and wiring. Beyond that, the VSS buffer module may have a problem. IIRC, all 1227165 ECMs had the external "strap-on" modules as a VSS buffer.

 

Vader, you are correct, I do not have Cruise control either. Part of me really hopes that this is the cause of some major problems, but the rest of me knows that I very well COULD have a leak. But my car is so clean and rust free that you could almost eat off the underbody!

I'll check up on the VSS when I have the car up this weekend. Hopefully I'll have my new tranny mount. I broke it when I gave it some serious pedal for the first time. Good thing it was from a roll.

On a side note, if the VSS is bad, how much is a replacement unit?

 

The last time I replaced one was about 1994, and it was a $75.08 item. The plastic gear was another six bucks or so. I'm thinking they might be a little more by now.

 

i paid 65 for mine. get it from the dealership. all the other ones don't work.

 

let me ask this. When the TC locks what happenes and what happenes if its not funtioning properly?

Does it just jerk the car bad at certin speeds or what??? somethings going on with my tranny and im not sure what it is

 

When the TC locks your rpms will go down. It almost feels like the tranny is shifting into a phantom 5th gear. The car will also feel sluggish in 4th gear when the TC is locked.

Its great for the gas mileage.

 

so when the TC locks up its good and it should do it?

When im crusing at about 30Mph and let go of the gas and slightly push it again the engine revs up just a little like its going to go faster then back down and the car starts shaking really bad. its accelerating but its like im driving a stick and i put it in 4th when it should be in second so its making the engine rev way down for the speed im not doing. what would cause the tranny to do that? That cable off the throttle connector that goes to the tranny??? have no clue what it is and how to fix it ????

 

KPT,

What year/model is your car? Some earlier EFI engines have programmed lockup points that are too low. I had the same thing on my '86 TA. It used to lockup at 28 MPH. The factory replacement "upgrade" EPROM changed that to 41 MPH, and it made a great difference in performance. Of course, there were a lot of other changes in the programming to help that out, too.

 

Its a 86.

Is that lockup what might be causing that jerking feeling like its switching gears back and forth reall fast at around 30 MPH?? and how do i fix that problem.. you know how much it $$$ to do that eprom???

 

???

 

Hehe, I figured out why cruise control doesn't work.....it seems that the two wires leading to the harness are cut! That would explain that issue.