My Torque Converter plug on the transmission has been unplugged since I bought the car. I don't ming it unplugged but is It bad to not have it plugged in? I have an 88 GT.

If you drive city streets in stop and go traffic it probably doesn't make much difference. If you drive on the interstate or other highways a lot then your gas mileage will be negatively affected and the trans will pay a price in extra wear due to the extra slippage and heat generated because the torque convertor is not locking up at those higher speeds.
Assuming your tranny is in otherwise good condition the fix is fairly simple and can be done easily. There are several past threads on here with good tips on the procedure.

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RickN
White 88GT 5spd
White 85GT Auto

You will get a little more wear and tear, and like he said use more gas. Automatics worked fine for 40 years without them. Think of it as a 4 speed that you always only use the first 3 gears.

If people actuall read their owners manuals, most even tell you to lock out overdrive gear in town driving. Most lock up around 45 right where your usually driving. Its better to stay in 3rd than to keep bouncing up and down between that and overdrive. My Magnum has a 5 spd auto and around city traffic I leave it locked into only 3rd. I leave the Corvette in ' D' and only in 'oD' when i get on freeway.

[This message has been edited by rogergarrison (edited 10-02-2004).]

The car has about 44,000 miles on it and I only put about 400 to 500 miles per year on it. I'm thinking best to leave it unplugged. I don't think that it's broken at all I just think the previouse owner didn't like it locking up and then un-locking all the time..

If you want better gas mileage, plug it in, that is if it is working. If it isn't working, it could cause your car to stall when you come to a stop.

There are three reasons that it may be unplugged...
The plug got knocked/fell off and no one noticed until now.
The plug was left off by someone doing previous service work.
The TCC had problems and someone left it unplugged on purpose.

I would plug it back in. If the TCC is acting up on TH125c it usually means the solenoid valve in the thransmission is bad. It's not teribly hard or expensive to fix. Plenty of Forum members have done it, including ones with only basic skills. You don't need to yank the trans to fix it. It's not an expert project but you do have to be a little careful or you'll have a leak from not sealing the side cover properly.

Older cars didn't have a TC lockup... That is true. But they also suffered both in performance and fuel economy. The TC had to be built to perform but was restricted from maximum perfromance by a need to have decent fuel economy and cut heat. The TC has always been the biggest heat source in the trans.

The TC clutch helps adress both problems. With the TC lockup, you can build the TC itself to provide more torque multiply, which also makes it "slip" more under other conditions. The TC clutch locks in high gear and does away with all the slip and the TC generated heat as well. The trans runs measurably cooler with the TC locked.

One a side note... When you are stuck parked in heavy traffic... put the car into neutral whenever you can. That will unload the TC and cut the heat it generates. The whole car will run at least a little cooler.

If you are only driving a few miles a year... I think I'd still plug it in and see if the thing is working or not. If it is working you really should leave it plugged in.

If you are having TCC problems right around lockup speed then you may want to look at the TCC delay product from Transmission Exchange Co. Some of the older ECM programming can make the TC shudder if you are hanging on the lockup speed. This is supposed to help stop that and isn't very dificult to install.

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The only thing George Orwell got wrong was the year...

The Ogre's Fiero Cave (It's also at the top of every forum page...)

quote Originally posted by black Fiero SE: I'm thinking best to leave it unplugged. I don't think that it's broken at all I just think the previouse owner didn't like it locking up and then un-locking all the time..

I beg to disagree and don't think it's a good idea. Under normal conditions you willl not notice it in operation as it is only a 2 - 300 drop in RPM.
Personally, I would repair it as I would anything else that would be not functioning in any car.

I would plug it in and see if broken also. While the cars may be different but, my '85GT automatic with 100K miles transitions smoothly from lock to unlock, it doesn't exhibit any hunting at any speed. Sometimes the engine lugs a little when the TC is locked at slower speeds but that if needed extra gas pedal unlocks it quickly.

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RickN
White 88GT 5spd
White 85GT Auto

OK.. I take everyones advice and try plugging it in. Like I said, When I bought the car the guy had it unplugged and said he only did it because he didn't like it kicking down on the highway. He said pontiac told him it would be about $300.00 to remove the TCC from the transmission and cheaper to just un-plug it if you don't like the performance with it on there.

Is this somthing I can plug in with out having to get under the car? Where is the port that I plug it into located? I can see the plug but havn't looked for the port yet..

It's accessible from the top. The connector is located straight down below the inlet to the throttlebody on the upper front side of the transmission housing.

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RickN
White 88GT 5spd
White 85GT Auto

The previous owner is apparently a twit. Plug it back in. It's easy to reach from the top on the front side of the transmission. The plug is Green if I remember right.

I'm going to try plugging it in and see if I notice a difference. Let me play the devils advocate for a moment..... Why would you want it plugged in other than to save a couple of miles per gallon? The most negative thing I hear people saying is the transmission heat however if you running 3000 RPM's with it unplugged and 2800 RPMs with it plugged in your still with in the engine / transmission operating zone.... Not being an expert , wouldn't it be fair to say that the reason Pontiac installed that feature was to give the car better gas mileage but a side effect is the transmission runs slightly cooler because it is run about 200 RPMs below where it would be at with out it installed??

It also would seem to me that by not using this feature it would allow for a quicker engine / transmission response ?

Again I'm just playing the other side of the coin. So far I have read 1/2 and 1/2 .... Some people say plug it in or your transmission is not going to last as long while others are saying leave it unplugged as it only serves to save gas???

Everything is relative. The extra wear is not going to show up tomorrow, next week, or maybe even next year. The Fiero automatic transmission got used in a lot of cars and I believe even mini-vans, the Fiero has to be one of lighter applications of that transmission. Again, I would say that in most city driving it won't make any difference but, the issue is not just a few hundred RPMs but that the unlocked TC is a pump putting work into a fluid. That work creates heat. When the TC locks up it quits adding so much heat to the system.
As to response, if the transmission is adjusted properly, the TCC should not hinder the performance of the transmission. Just today I was pulling onto the interstate. I was going up the on ramp with the TCC locked, then at the top of the ramp, traffic required that I pick up the pace and with more throttle the lock disengaged, then with additional throttle the trans downshifted for increase accelaration, all done smoothly and predictably as required.

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RickN
White 88GT 5spd
White 85GT Auto

I would plug it in and make sure it works. If it does not work I would fix it. It is an easy, cheap fix. It will save wear on your transmission and save you a little gas.

I posted transmission tips recently, here you go.

Just installed a new TCC solenoid and third gear switch in the automatic transmission.
Here are some specific part numbers and tips that I learned along the way that will help you out.
I have a 87 GT with V-6 and automatic transmission.
The job took me about 5 hours but I took breaks to run to the auto parts store and coffee breaks.
I could have cut the time in half if I had known about these little tips, tools and parts.
Anyone with basic shade tree mechanical skills can do this job and hopefully those folks who are thinking about doing this themselves will find this little write up quickly in the search feature.

Through GM Parts Direct
Part # 8643710 3rd gear switch is $3.14
Part # 8689901 is the valve solenoid at $20.91

Through auto parts store;
Felpro valve body gasket # TOS 18661 at $7.73
Two quarts of transmission fluid.
Torx bit # 30 ( I purchased a nice 12 bit set for $13.99)
Trouble mirror
Shop towels
Brake clean spray

Jack up car, use a jack stand and remove left rear tire, remove rubber tar skirting.
From the top, remove air cleaner to throttle body tube, transmission hose bracket 15MM and your ground wire 15MM.

"Tip",,,,,,,,,,Remove the retaining clip from the transmission shift cable bracket then put the car into 1st gear and pull the cable up and out of the bracket so you have room to pull the cover out later.

Remove the 13MM bolts on the valve body cover from the top and through the wheel well. The lowest two 13MM bolts you need a small 1/4 drive 13MM or a box wrench to fit into the tight space.
The cover is removed out the top. Have a shallow baking pan or a pile of old "throw away" towels under to catch fluid which is only about a quart.
Solenoid is removed with # 30 torx, I worked from below the frame with a couple of extensions. 3rd gear switch is removed gently with a pair of channel lock pliers.
Note the position of the solenoid connections and remove.

"Tip",,,,,,,,, This is where your trouble mirror comes into play. The connector is just out of view so work from the top standing in the truck, use a small screwdriver to release the retaining clip from the top of the solenoid connector and the connector will pull out.

"Tip",,,,,,,,,,Remove the transmission banjo cable from the throttle body and just let it rest. This will lower the position of both the cable and the lever inside of the transmission and will afford you much more room to re-install the solenoid connector. I took me an hour trying to trying to get that connector back on until I "discovered" this tip. With the cable and lever out of the way, it takes only a couple of minutes to connect it while using the mirror.

I reused the old plastic long wire sleeve on the new solenoid as it did not come with it from GM Direct.
Clean up the pan and the gasket mounting surface with shop towels and brake clean and prepare to reinstall cover.
"
Tip",,,,,,,,,, I threaded a couple of bolts through the gasket to hold it in place against the cover while I positioned it for final installation.

I couldn't get a torque wrench into the tight spaces so I guessed by hand and I also used a small 1/4-inch drive ratchet wrench to help me from over tightening the bolts.
Basically that is it, reinstall everything, add some transmission fluid and double check the levels when hot.

Here are two links that I found that have nice descriptions and instructions on this job.
The Fiero TCC (Transmission Lockup) Solenoid by Chuck Kichline
TCC troubleshooting and repair by Oliver Scholz

It is not a bad job at all, just tedious, just keep thinking to yourself that you are saving between $400.00 and $600.00 to the transmission shop. You are also extending the life of the transmission as well as improving your gas mileage.
One last "Tip" for you; clean the transmission case cover and the area around it real well with a can of engine cleaner a day or two before you do the work. You don't want dirt or debris getting into the transmission and it is always much easier to work with clean parts.
Best wishes and good luck to you on your repairs.
jetman

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jetman
Silver 86 SE 2M6 4-speed, with "check wallet light" and "hockey withdraw pains"

Nice write jetman!

quote Originally posted by jetman: ...It took me an hour trying to trying to get that connector back on until I "discovered" this tip. With the cable and lever out of the way, it takes only a couple of minutes to connect it while using the mirror...

Yes, excellant write-up.

If I could offer one other thing on this subject. If I had to do this again I would not worry about getting a TCC solenoid with the connector as many had suggested. The job would have gone much faster if I had just cut the wires and spliced them instead of trying to disconnect and reconnect the solenoid connector.
However, If you really want to use the connector, I discovered that the solenoid connector actually connects to a "pass-thru" connector that clips into the transmission housing. You can depress the latch clips inside the transmission housing (after removing the valve body cover) and pull the pass-thru out forward of the tranny housing a couple of inches. There's enough wire that once pulled out you can actually "see" the connector, to plug the TCC solenoid back in. The pass-thru connector is a plastic connector with o-rings on the OD that seal against the tranny wall. It is also the connector that the original loose external TCC wire was supposed to be connected to.

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RickN
White 88GT 5spd
White 85GT Auto

quote Originally posted by black Fiero SE: Why would you want it plugged in other than to save a couple of miles per gallon? The most negative thing I hear people saying is the transmission heat however if you running 3000 RPM's with it unplugged and 2800 RPMs with it plugged in your still with in the engine / transmission operating zone....

The big item is heat..... As I stated above the TC is the biggest generator of heat in the trans. It is second only to the engine for the amount of heat generated. Locking the TC stops it churning the oil and stops it generating heat.

The transmission itself generates very little heat while cruising.

The difference in fuel consumption come in more if you do allot of highway driving... The more the TC is locked the more "free" miles you'll get compaired to a TC that is unlocked and slipping all the time. A difference of 2 MPG on a 10 galon tank is 20 miles more range between fillups.

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The only thing George Orwell got wrong was the year...

The Ogre's Fiero Cave (It's also at the top of every forum page...)

quote Originally posted by theogre: ...A difference of 2 MPG on a 10 galon tank is 20 miles more range between fillups.

When the TCC solenoid in my Formula died, 2 MPG is about what I lost.
I fixed it, not too long ago.

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Raydar
88 3.4 coupe...........

Coming soon...
88 Formula, presently under the knife.
Read Nealz Nuze!

OK... I plugged in the TCC today . The first thing I noticed was that my RPM gauge didn't work. It was at 0 (or as close to 0 as possable). I still took the car out for a test drive. I only got it going about 40 to 45 MPH and did not run it on the highway yet. I brought it back home and unplugged the TCC and started the car and the RPM gauge is back working again. Any Ideas whats going on with this? I would like to get everything working right. How is the TCC related to the RPM gauge ??

The ECM is connected to the dash. That's how it gets the speedometer feed.

However... The TC lock circuit runs off the gauge fuse.... If the TC lock system has a problem, there is a chance it could be pulling enough power to mess up the gauges and not automatically blow a fuse. An ohm meter might turn up a partial short inside the transmission. You should have an open (infinite ohms) circuit between the terminals on the trans case and the trans case itself. If you read any ohms then there is a problem inside the trans.

The gauges should have only a 10 amp fuse in the fuse box. Check and make sure some twit didn't shove a larger fuse in.

So If there is a short in the transmission case then replacing the TCC Solinoid (don't know how to spell it) should fix the problem? Is it possable that if I cleaned the TCC terminals that plug into the transmission this would do anything? I guess the TCC plug has been unplugged for some time. I'm thinking the person I bought the car from new that there was a problem with the TCC thats why they unplugged it. The person was telling me when I bought it that they unplugged it because they didn't like the lower RPMs on the highway and that Pontiac quoted him around $200.00 to take the TCC out of the car but I am thinking he had a problem with it and they wanted $200.00 to fix it??