Hi all,

I went ahead and pulled the electrical connection for the Torque Convertor and drove around. The car is finally running correctly. The shifting smooth and
strong and no more pinging overload sound from my engine :D
yeee haaww.....
now I have to figure out why this plug isnt working.....
I took my car and got the emissions test done - it failed the NOX level ...I got a I got a 2903 and only 1047 is allowed :confused:
Please tell me this isnt related.

Thanks
Kevin

below is the original message.
Hi all,

someone please explain this Torgue Converter Lockup switch to me.
my trans has been acting funny and I think this lockup switch may be the problem.
Shifting is smooth while the car s warming up.
By the time the car warms up the car is shifting all the way through 1st, 2nd, and into drive
by the time I get to 20mph. Plus , it feels like it is constantly slightly shifting in and out until I get at faster speeds. Its just generally not shifting right.....but if I get on it a bit , it shifts much better.
Sometimes it pulls like crazy...smooth , strong.

The trans was rebuilt about 2 years ago.

I looked into the Modulator and it seems okay.

Something is just funky and i dont think the trans is bad.

Alot of times when Im going down the road at 20 or so , It feels like Im driving a stick shift car
and Im in 5 th gear..........weak, slow , chugging.

he car runs great when cold.

The only thing I can think of that has changed since the trans rebuild is the thermostat.
I replaced it with a 180 degree version in place of the 195 original.

This is just nuts. sometimes I will be driving and the engine has the too much load becasue the trans
is in drive at 20 mph.....ping ping ping goes my engine. then as I speed up ...Bang everything smooths out and off I go...smooth and strong.

I suppose I should just take it back to the place that rebuilt the trans and let them deal with it.

Thanks
Kevin


[Modified by ksems, 2:08 PM 3/14/2002]


[Modified by ksems, 2:09 PM 3/14/2002]

 

also , i have checked the fluid level.
it is perfect and a nice pink color...

what gives? :confused:

 

oh , for those that cant see the sig, my car is an 81 Automatic.....stock engine

 

If not wrong here, 350 TH don't have lock up switches. At least I don't thin mine does. Lock-up switches are usually found on Overdrives. I could be wrong.

 

It sounds like the converter is not unlocking when reaching lower speeds causing the jumps/bucking you describe. I think there is a switch under the brake pedal somewhere that could be worth checking. What happens when you come to a light or a stop sign? The engine doesn't stall does it?

 

stingy ------

yes my engine does TRY to stall sometimes....but only from a dead stop to 5 mph.

Howd you know that? :)

I can come to a stop and it chuggs a little at first, then I get to the next stop sign...not quite as bad.
Ive been trying to go easy from a dead stop.

By the way , i think Ive eliminated any spark problem as the problem was there before i replaced plugs,wire, ignition coil, blah blah blah

Thanks
Kevin


[Modified by ksems, 12:46 PM 3/11/2002]

 

Budman....maybe its the TH350c then.....

 

Believe the '81 has the "350C" which DOES have a lock up torque convertor, which is controled by the ECM(computer) which will lock up the torque convertor in both 2nd and 3rd gear. The ECM sends a signal to lock up the torque convertor, once the engine has warmed up (a thermostatic switch sends this signal to the ECM) which is sent electronically and is accomplished with the electrical connection you will find inside your 350C automatic transmission, if you remove the pan for an oil and filter change.

In an earlier I post I was involved in, I was told that some people unhooked this electrical connector to disable the torque convertor lock up to eliminate this annoying condition which you've described, which I also have to some extent in my '81. Guess unhooking the torque convertor lock up, doesn't do any harm, other than costing you some gas mileage.

 

81' and 82's used a TH350C which did have a lock-up.

Ad for the problem, I think the lock-up is controlled by your computer. There should be a electric plug going into the side of your trans. If you pull that plug, it should only prevent the convertor from locking up. Iwould pull that first to see if you still notice the problem and if it seems to go away, I would plug it back in and start checking sensors and wires going to the computer to find the cause.

 

gerry -

any harm in just unplugging it.

I already swapped out the computer as well, didnt solve it. Maybe its a wire from the computer...

also, does the thermostat have any direct relation ship to the converter switch?

Thanks all

Kevin

 

We've had plenty of cars come through the shop where I used to work with the stalling problem. Runs fine on the highway until you have to stop. The converter continues to stay locked and the engine can no longer hold the load so it stalls. Same thing as not pushing the clutch in on a standard transmission. When this happens I think the lockup solenoid becomes jammed or something and is unable to perform it's job of unlocking the converter. I don't know much about the TH350C transmission, but the problem I speak of is very common. I'm just not sure of the exact fix for it :)

 

Learn something everyday. :yesnod: Thanks. That tells you why I paid someone to rebuild my 700R. :)

 

No harm. It would be just like having a regular TH350. But lockup converters are a good thing, so i'd look into having the probem fixed. Uplug the switch as a temporary quick fix.

 

stingy - thanks
what was the deal with the attempted stalling thing? ......that you asked...

kevin

 

The converter continues to stay locked and the engine can no longer hold the load so it stalls. Same thing as not pushing the clutch in on a standard transmission.

 

man thanks very much for the quick , and I believe right on the money , info.
I'll check the brake switch thing and also try unpluggin the trans connection it to see of the problem goes away.

I believe this IS my problem......

I may owe ya one !

kevin




[Modified by ksems, 1:11 PM 3/11/2002]

 

The thermostat may have a bearing on this. I know the convertor is not commanded to lock up until the engine reaches operating temp but I do not know what that temp is.

I am not well versed on the th350c since my '81 has a four speed. I do not think the problem is with a wire from the computer, but maybe a sensor going to the computer. Any ideas if you changed anything aboutthe same time the problem showed up?

Myself, I would probably unhook the lockup while driving the car normally while looking to find the problem. All the locking and unlocking you talk about can not be doing the convertor any good and is slightly shocking the drive line each time it locks.


added.....

Darn, I've been posting too much. With this post I hit 100! Guess I should keep my mouth shut
:eek:


[Modified by gerry c, 8:55 PM 3/11/2002]

 

You're lucky - my converter stopped locking up altogether!!
Don't unplug the connector at the gearbox as it's awkward to get to & easily broken. If you follow the wires up the side of the block, they come to another connector just behind the rear of the D. side valve cover. This one is easy to disconnect. Try disconnecting this & drive the car. If the problem still continues then you've ruled out the computer & electrics. The TCC brake pedal switch just cuts off the current that causes the solenoid to lock the converter. The temp sensor for the ECU is just to the right of the thermostat housing (should have 2 wires going to it) & may be worth checking.
:cheers:

 

Well, first I haven't the answer to his problem. But, my '80 also has the 350C with lockup converter and NO Computer.

Doesn't the solenoid that locks the converter work from vaccum & temp?

The temperature won't let it lock up until it reaches operating temp and the brake switch kills it if you apply the brakes, but I thought that the solenoid was vaccum actuated. When it reached a lower non-accelerating vaccum level it would then lock.

If I hadn't loaned my shop manual out I'd look it up. JIM

 

Jim,
From what I know the '80 used vacuum & temp for lockup as you say. The '81 had the "luxury" of the computer getting involved in it. The bottom line is that a current is passed through the solenoid via terminals A & D (I think) on the g/box connector to lock the converter.

From memory this is how my '81 should work:
12V is present at terminal A(?) on the g/box connector. This connector goes to the solenoid & the current return path comes out on terminal D(?), which is then connected to the EGR/TCC relay. When the relay "throws" this wire is then effectively earthed, allowing current to flow through the solenoid which will lock up the converter.
To "throw" the relay there is another 12v supply going to it via the TCC brake switch (brakes on, then no current reaches the relay). This 12v goes through the little solenoid in the relay & then goes off on it's merry way to the computer. When the computer is happy with the temperature & vehicle speed, is in closed loop & all the other things it wants, it will connect this 12v to earth. This lets the 12V from the TCC brake switch flow through the relay, causing it to "throw", which will then connect the 12V going through the TCC solenoid to earth (ground?), thus locking up the converter.
The wire from the EGR/TCC relay to the computer should be tan/black & there is a test point (922) on it somewhere (think it's on the ALDL connector - can't remember).
Worth checking that the EGR/TCC relay is behaving itself. If it is stuck in the "thrown" position then nothing the computer can do will turn off the lockup (only operation of the brake would - if the brake switch is adjusted correctly). My EGR/TCC relay was bad, so I ordered a new one, waited ages for it to be rowed across the Atlantic, paid a fortune in duty, fitted it and..... it still doesn't lock up :mad
I hope the above is how the '81 confuser system works (if I'm wrong then it would explain why I can't get my converter to lock!). I think "thrown" is the correct term for the relay (our analogue electronics engineer is always talking about "throwing" relays, but I daren't ask - I can't face a 2 hour lecture on relay design).
I don't know anything about the insides of auto trans, but many people have told me changing the oil & filter might solve it, as small amounts of dirt can really mess things up.
Hope some of the above ramblings help (it's woken me up trying to remember it all!). These lockup converters can drive you insane when they start playing up :(
One more thing - there is a test connector in the wire from the g/box to the EGR/TCC relay. This connector is under the d.side cover on the centre console, somewhere near the ashtray (which will be overflowing once you start trying to fathom out confusers & lockup converters!). You can connect a test light to this connector to work out what is going on. Can't remember the details, but I remember driving around at night with a stupid dim lightbulb tied around the drivers mirror & a flowchart taped to the dash! That's it, just thinking about TCC lockup has made me :mad :boxing so I'm outta here!
:cheers: