Posted by ChuckRock on May 14, 2009

Here’s a small tip that I found out as I started upgrading the body on Terri’s new 86 Fiero Coupe. You don’t realize how much you miss a power deck lid release until you don’t have one. This is one of the easier upgrades you can do since GM takes the cheap way out and makes all of their cars with the wiring already in place, which is good for us. Again as with most modifications you can do this several ways:
Take a whole deck lid from a car with the release, which is good if you’re already changing the deck lid in an upgrade. Take the power release and latch off of a donor deck lid. Take just the power release solenoid and attach it to your deck lid. The first choice is the best, since you get the wiring harness that’s built into the deck lid. All you have to do is bolt up the deck lid and hook up the wiring. We’ll get into the wiring issue later. The second choice is to unbolt the whole latch assembly (2 10mm bolts) and switch it out with a power latch assembly. If you need to change the lock for some reason now is the time to do it. When the latch is removed all you have to do is remove the two Philips screws from the plate that’s behind the latch and pull out the plate, which holds in the lock cylinder. Pull the lock out through the latch side. The last choice is to take the solenoid itself and bolt it up to your existing latch. First you’ll have to pop out a small knockout plate on your latch and then bolt up the solenoid, which is only attached with one bolt. The wiring is the next thing. All Fieros should have a pigtail hanging out of a wiring harness below the right or left deck lid hinge. You hook this pigtail up to the harness coming out of either the left or right side of the deck lid (if it’s a power deck lid). I found that some 84’s and 85’s have a small one wire hook-up coming out of the left side and the 86’s on up seem to have a four wire plug coming out of the right side. If you don’t have a deck lid with a harness than you have to make one. The solenoids only need one wire that’s hot and the ground it gets from the latch when it contacts the body. In fact, some of the cars I’ve done with heavy spoilers or wings sometimes have needed a separate ground wired to it since it doesn’t always make contact properly. The switch is the easiest part since you just bolt up a release switch into the instrument cluster and hook up the wires, which are already there. The last thing is to find the pigtail under the dash, above your right knee. It should be a three-wire pigtail and you’ll need to plug in a relay.	Typical Decklid Release Switch
	Underdash-mounted Relay
	Solenoid Mounted on the Decklid Latch
On Terri’s Fiero, which we call Blackie, I actually did it two ways. First I had hooked up a non-power deck lid with a mustang spoiler. I took a solenoid I had, removed the knockout plate and bolted it to my old latch. Then I had to make a wire harness and used wiretaps to hook it into the pigtail. Next I just hooked up the switch and plugged in the relay. Because of the weight of the spoiler I had to hook up that separate ground wire I talked about. About a week later I got a knock off Fiero GT wing. I had an extra 85 GT deck lid so I bolted that up with the wing. This was a power deck lid but being an 85 it had the wire coming out of the left side, so I had to run that to the right side where my connector was. I had to swap out the locks so I could keep my key, but now I can open the deck lid with a push of a button! Keith and Terri

Posted under Electrical

Posted by ChuckRock on April 27, 2009

Torque Converter Lockup.

Why is TC locking important?

The biggest reasons are fuel economy and heat control. The TC is the car’s single biggest heat generating device besides the engine. The transmission will run significantly hotter if the TC doesn’t lock. Before listening to people that tell you it doesn’t matter read this article from Borg Warner. Borg Warner Tech Tips, Transmission Fluid. It will also increase heat load on the radiator since it also cools the transmission. That could lead to easier overheating if the cooling system isn’t 100%. With the TC locked there is almost no heat from the transmission.

You’ll also waste gas. Likely allot. One of the advantages of having a locking torque converter is that it allows the TC to be built with more “slip” which increases the torque multiplier effect. This increased multiplication translates into quicker launches but horrible fuel consumption. Once the transmission reaches top gear, the TC is locked eliminating the slip that is now just wasting fuel and making heat. This is why today’s automatic transmissions both perform better and get nearly the same fuel economy as a manual transmission would. To learn more about the locking TC, go hear–> Motor Magazine Back Issues, and select the May 1999 issue then go to the bottom of the next page that opens. If you have acrobat loaded just get this–> Motor Magazine Torque Converter Article PDF.

Testing

TH125c has a locking torque converter system controlled by 4 electrical items. They are listed in the order of their location in the circuit. (Starting at the fuse end)

1. The Brake Pedal Switch. This switch opens to unlock the TC when you press the brake. It is on the brake pedal hardware.
2. The Third Gear Switch. This is inside the transmission. It closes only when the transmission is in third gear.
3. The Converter Lockup Solenoid. The device operates a valve that pressurizes a clutch and locks the converter.
4. The ECM. The ECM switch closes a connection to ground only when the car is doing a fairly constant speed above 35mph.

There are 2 tests for problems with the Torque Converter lockup system. These tests should BOTH be done before any shift problems are looked at. The first, and easy, test for TC lock is to press the brake while doing a constant speed over 35mph. (The test WILL NOT work if you are accelerating or slowing.) You only need press the pedal enough to activate a switch. (About 1/2″ ­ 3/4″) If the TC is working right you should see the tachometer jump up about 200RPM then drop again when you let off the brake.

The second TC test is to pull the TC lock’s electrical connector. It’s on the front of the transmission. Unplug it and see if you still have problems. The second test is very important if you are stalling when stopping the car or if the car bucks badly when slowing. There are known issues with the Torque Converter Lockup Control Solenoid. This device can hang the Torque Converter Clutch in the locked mode, usually when the transmission is hot.

If the second test stops the problems then the TC control solenoid likely needs to be replaced. This repair can be done with basic tools. It’s not hard just very time consuming. The Solenoid is under the side cover of the transmission. While replacing the solenoid it’s a good idea to replace the Third Gear Switch, which is next to it. Then you’ll have all new electrical parts in there. If you don’t see the RPM jump while doing the first test you may have a TCC apply problem. This could be electrical, TCC solenoid, TC clutch or hydraulic problems.

The test for the brake switch is in the Manual lockup section at the end of this page. The test for the Third gear switch is a bit different. If you watch ALDL terminal F with a voltmeter you’ll see it go to 12V when the TG switch closes but then you’ll see it drop again when the switch in the ECM closes. At this point you’ll be able to watch the ECM lock/unlock the TC depending on driving conditions. This only tells you that the electrical system is OK. You could still have a hung TC solenoid or other problems in the transmission.

Once the electrical problems are ruled out then it’s either solenoid hydraulic or the torque converter itself. Hydraulic or TC problems are beyond most people but if you do work on this yourself the best source of information on this is a GM document that covers the whole TC lockup system step by step. A very good general guide on this was provided to trainees at a GM seminar and is not part of the shop book. It is however on ALLdata. You may be able to get this from a friendly shop. I think ALLdataDIY.com may also have it.

Reading the TC ID Label There are different Torque Converters used with the various engine and transmission combinations. The V6 TC may not perform properly on an L4 and vise versa. I don’t think the 3T40 torque converters will work in the 4T60. (I don’t have any way to check.)

The ID label may still be on many converters, here’s how to read it. (The following TSB has been reduced to cover only 245mm units. The larger 298 mm units are used with inline transmissions.)

Torque Converter Identification
TRANSMISSION: GM All
BULLETIN: # 010 REVISED
SUBJECT: Torque Converters
DATE: September 1990
GM Torque Converter I.D.

The 245 mm dia torque converter I.D. code works the same way as the 298 mm converters, but with different meanings.

The first digit of a 245 mm converter refers to the application.

F = Front wheel drive
H = Rear wheel drive (except THM 180’s)
S = THM 180

The second digit is the “K” factor. The chart shows the “K” factor for each code along with the stall speed. Note: Multiply the “K” factor by 11.6438 to get the stall speed of a 245 mm torque converter.

CODE   K FACTOR       STALL SPEED
A      240            2795
B      220            2560
C      205            2385
D      180            2095
E      160            1860
F      148            1720
G      140            1630
H      130            1514
J      177            2061
K      237            2760
L      163            1897
M      131            1525
N      218            2538
Y      122            1420
Z      203            2363

The third digit refers to the clutch type.

CODE DAMPER TYPE
0    No converter clutch
1    12O ft/lb
2    104 ft/lb
3    170 ft/lb
4    215 ft/lb Heavy Duty
5    215 ft/lb *RTC
6    170 ft/lb Heavy Duty
7    215 ft/lb *RTC Heavy Duty
8    Viscous Clutch
9    240 ft/lb
A    215 ft/lb
B    215 ft/lb *RTC

* RTC = Reverse Torque Control (poppet valve)

The fourth digit (optional) refers to the type of cover used.

CODE COVER TYPE (APPLICATION)
A    FWD 208.2 mm Bolt Circle
B    FWD 237.0 mm Bolt Circle
C    FWD 237.0 mm Bolt Circle (viscous Clutch)
D    RWD 247.65 mm Bolt Circle
E    RWD 237.0 mm Bolt Circle, No Converter Clutch *
F    RWD 237.0 mm Bolt Circle *
G    RWD 247.65 mm Bolt Circle *
H    RWD 247.65 mm Bolt Circle, No Converter Clutch *
K    RWD 237.0 mm Bolt Circle, No Converter Clutch *
P    THM 180 ISUZU
R    THM 180 Opel
S    THM 180 BMW

* 180 degree weld on each lug

Look at the code on the torque converter in figure 6. You can easily identify it as a front wheel drive model. (The first code is an “F”). The stall speed is 2760 (the second code is a “K”), and it has a damper assembly rated at 120 ft/lb’s (the third code is a “1″.) Notice that the fourth code has been omitted.

Manual TC lockup.

Warning! Manual TC locking presents a number of problems and can damage the transmission. It is potentially dangerous to drive with a manual lock active. Manual locking should ONLY be considered when the ECM has been removed such as when a carbureted engine has been installed.

Notice! This is an EXPERT level article and it assumes the ECM was unplugged and that the wiring is intact. If the harness has been cut it is up to you to return it to operating condition. This topic is only covered as an aid to installation of non-stock engines.

Manual locking of the TC WILL NOT help performance. Manual locking is used only help gas mileage on cars without an ECM. Even then it is preferred to find an automatic solution to the problem. On cars with an operational ECM, delaying the locking of the TC can help performance. This company can tell you more about that-> Transmission Exchange Co.

Before you can install a manual lock. You need to test the brake and third gear switches. BOTH switches Must work. Without both switches you cannot wire the manual switch without damaging the transmisson.

There are 2 wires on the TC lockup connector. The first wire, according to GM schematics, comes from a switch on the brake pedal. The other wire coming from the transmission connector is ground. The ECM used to ground that wire to activate the TCC. Your new switch will replace the ECM.

The brake switch. Disconnect the transmission plug and hook a test light to the wire that is always hot with the key on and hit the brake pedal. The line should go dead. If it doesn’t you can’t wire the switch manually. The Brake Switch MUST work or you’ll have nothing but problems. Dangerous problems.

The third gear switch. This switch must also work or the TCC may try to activate as soon as you take your foot off the brake when stopped. This is not a good thing. (Same effect as dumping a clutch every time you take your foot off the brake. You WILL brake the tranny like that.)

To test the third gear switch connect a voltmeter between the TC ground wire and body ground. TCC ground is Terminal F on the ALDL. Put the meter where it can be seen while driving and have a passenger watch it. When the car goes into third the meter should swing up.

Warning! You MUST use a voltmeter for this test! Test lights may pass enough current to allow TC locking. This is not a good thing just now. This wire should only be hot when the transmission is in third gear. If you see a voltage on the line when stopped then the third gear switch is bad.

The manual lock switch is connected between the transmission ground wire and the vehicle ground. When the switch is closed the Torque Converter will lock anytime the transmission is in third gear.

Manual locking presents several problems!

You want to avoid using the manual lock except for highway driving. You don’t want the tranny locking as soon as it hits third gear, which is exactly what it will do with the switch on. If the TC locks at the same time you hit third you’ll likely tear up the tranny. (You also lose some performance that way.)

If you get into heavy traffic you’ll want to leave it unlocked, even if the tranny stays in third.

The most obvious method to do this is a simple toggle switch. Problem is a toggle switch doesn’t allow for the driver forgetting it’s on. If the toggle is on then the transmission will lock as soon as it hits third gear, which isn’t what we want for either reliability or performance.

The preferred way to restore TC locking is to make a speed sensor for the circuit. That way the TC will never lock below a specific speed. The ECM cutoff was no lock below 35. In most cases setting the cutoff for no lock below 35-45, and add Transmission Exchange Co.’s TCC delay unit, would return auto locking in the safest way possible. Ideally the speed sensor should only lock at relatively constant speed. It should unlock when speed changes rapidly.

A second option is to make a control with a push button. When the button is pressed the TC locks but when the brake is pressed or the transmission goes out of third gear the circuit resets and leaves the TC unlocked. This gives the same result as a simple toggle switch on the highway without some of the safety and drivability problems. (This circuit is Very easy to do and really cheap.)

Either control circuit would be fairly easy to do. There’s a 2000ppm feed back to the ECM connector from the dash. There’s any number of ways to make that feed close a switch at a particular speed or above.

Posted under Transmissions

Posted by ChuckRock on April 23, 2009

The Fiero TCC
(Transmission Solenoid Lockup)

by Chuck Kichline

http://www.kichline.com/chuck/fiero/TCC.htm
7/10/2008

I found out that there wasn’t a lot of information on automatic transmissions for the Fiero on the web, and even worse, both the Haynes and Clymer manuals are weak on diagnosis and had NO information on repair.  It became very important to me when my Fiero started staying locked up, stalling the car in traffic and endangering my LIFE!  Since the commercial manuals are no help at all, I started a search on the web, and finally found the information I was looking for.  Here is what I learned..

What is the lockup solenoid?  It’s an electrically operated valve in your Fiero automatic transmission that is controlled by the car’s computer.  When the computer believes it would be effective to lock the torque converter up solid it powers the solenoid which makes the transmission lock up.  The effect is that “fourth” gear that you sometimes feel on what is really a three speed automatic transmission.  The effect is better gas mileage, as it reduces the speed of the engine by about 250 RPM when it cuts in.  Not a whole lot, but good for a couple of miles per gallon.

What can go wrong?  Like all the other electronics on these cars, they can fail.  The failure may be that the lockup doesn’t happen, or that the engine stays locked up when coming to a halt, or blowing fuses.  If the lockup doesn’t happen it can mean poor gas mileage (18-19 mpg in a V6), the engine revving faster than it should, and possibly running warm or even overheating. Blowing fuses gets you the same result, since the lockup doesn’t work. Having the lockup stick on can be very dangerous, and leave you stranded in traffic in a car that won’t go into gear – or won’t properly kick down to pass.

How can I tell if my lockup isn’t working?  Do you occasionally feel what feels like a fourth gear?  Then it’s working.  If you want to test it, take the car up to about 55 on a level road, and press lightly on the brake pedal.  It should disengage the lockup, and with a steady foot on the gas, you should see the tachometer move up by about 250 RPM just as the brake lights go on. Another hint is that when coasting down from speed, it should disengage at 45mph – it feels like the car is speeding up on coast down, because when it disengages, the car starts freewheeling.

How can I tell if it’s sticking?  I had that fault, and it feels just like you forgot to put in the clutch in a manual transmission as you pull up to a stop light. The car stalls, if you’re lucky it will unstick and when you restart the engine. If you are unlucky like me, you’ll be stuck in the slow lane of the freeway with a car that will not move!  I finally got it out of traffic by revving the engine and slamming it into gear, and got out of the way in five foot jumps.  Not a good thing.  It had done it a few times before, but had always healed itself after the car died.  The previous owner had mentioned having some transmission work done, a “shift kit” (after I bought the car) and my guess is that she had had the work done only to find out that it still had the problem.  I guess that’s a good thing – otherwise she’d still probably be driving her car! What do I do if I have a problem?  If it isn’t locking up you are working your car harder than you should, higher revs and more heat.  You ought to fix it.  If it’s locking up and staying locked up, I suggest unplugging the lockup connector – that’s the green connector on the left front of the transmission “bell housing” behind the engine.  That will make it NOT lockup ever, and puts you in the no lockup mode.  It’s probably safer than getting caught in traffic and not being able to drive home!  If the transmission is locked up, the problem is probably in the solenoid being physically stuck or plugged, so just unplugging the connector while the engine is locked up doesn’t help, but it will keep it from happening again.

I risked trying the repair.  It turned out to be relatively easy, and I bet saved me several hundred dollars.  This is what I know, maybe you can do it too?

The lockup solenoid is under the cover on the left SIDE of the transmission. First we need to remove the cover.  From the top of the car remove the carb/aircleaner tube, the bolt that holds the transmission cooler hose (first arrow) and all of the bolts that hold the side transmission cover that you can reach from here (second arrow).

Here’s the solenoid connector that I mentioned earlier.  You don’t have to unplug it now if you haven’t.  See that the other stuff is now out of the way. Now jack up the car and pull the left rear wheel.  Put the car on a jack stand.

Remove the “tar paper” skirting between the inner fender and the frame.  It’s mounted mostly with reusable plastic pop rivets, just pull out the centers and put them back together to reassemble it with later. Tuck the skirting over to the side as you can.  Here’s the side cover from the wheel well. Looking down on the valve body after removing the side cover.  There should be just a little ATF in the side cover, so be ready to catch it when you take the cover off.  Pull the cover out the top.

OK,  here’s the valve body from the side.  The two wires come from the lockup connector.  Here’s the theory – there are TWO components in line. First the lockup solenoid then a pressure switch.  When the computer turns on the circuit it should close the lockup solenoid and the transmission should lock up.  In line with the lockup solenoid there is a pressure switch that is normally open, if the computer tries to lock up the transmission but there is not enough pressure the pressure switch is open and it doesn’t lock up – a mechanical interface to the transmission.

Those are the parts that I have highlighted.  If the transmission stays locked up, the problem is most certainly the solenoid and it should be replaced.  If it doesn’t lock up it could be either the solenoid or pressure switch.  Replace them both.  If it’s shorting, it could be either solenoid, switch or wires, check them all.  You may want to replace everything anyway, since it’s already apart. These parts are NOT going to be available from an auto parts store.  You will have to go to a transmission shop or dealer to get them.  I went to a transmission shop and was treated REALLY fairly.  You’re looking for the “transmission lockup (tcc) solenoid, pressure switch, and side cover gasket”. Ready for the cost?  About $20 for the solenoid, about $10 for the switch, and about $5 for the gasket.  YOUR PERFORMANCE MAY VARY!  Take the

side cover so they know for sure what transmission you have.  They’ll probably have to order the parts so go home and clean things up. I see that The Fiero Store stocks the solenoid now;  convenient, but at twice the price.

Here’s the inside of the cover – ready for cleaning.  Don’t forget to clean the old gasket off the cover and transmission body.

Here’s the solenoid out and sitting on the frame rail.  It’s held in by ONE T30 star screw.  I’d always used just a hex wrench before on these things, but it didn’t want to come loose so I bought a 3/8″ drive set with about seven different sizes.  It cost about $15 and those star screws are all over GM cars anyway.  It came out easy. Pull it down out of the valve body.  The pressure switch is a big hex, you may have to buy an “oil sender” type socket to remove it – it unscrews.

Here’s a real bad picture of the solenoid kit I used.  You cut the wires on the old solenoid and then use the quickie splices to install it.  The positive side of the solenoid goes to the wire directly to the lockup connector (and the negative goes to the pressure switch).  I’ve been told that the OEM solenoid comes with the wiring harness and connector.

Then you just put EVERYTHING back together.

So here it is all back together again.  I can say that I fixed my automatic transmission and it was relatively EASY!  Actual work time was only four or five hours.  I suggest that you change the fluid and filter now.  About six months after I fixed my TCC the transmission started slipping, but was fixed by changing the filter and fluid again (it had been changed before I replaced the TCC).  My guess is that the random lockup had kicked a lot of clutch plate parts into the fluid and they plugged up the filter.

I’d like to thank everybody that helped me, and hope that this helps others.

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Permission to publish in any newsletter or web site with credit.

Posted under Transmissions