Got the "actual gear indicator" and TCC lockup working, now...
Fatfenders
Posts: 39
I am thinking about actually building my own transmission control unit (TCU).
The very reason I·built my current BS2 is because after less than 15k miles (in 2 years) the TCC function got flakey and now, a problem that occured when I first got the car running is showing up again, in spades. Early on, the car would not shift into 1st and 4th. I would stop. Cycle the ignition key, and it would be OK for a day or a week. Oddly, that problem went away... until yesterday (interesting coincidence). Now its seems to be permanent.·I was never fond of that unit in any case. Found out that "TCI" markets the unit but no one there know anything about it so tech. help has always been useless. The install/user manual was cheezy, the GUI interface was primative, etc.
There is a new unit out there (PCS) but its another 850 bucks.
So now that I have found out that mere mortals can do this stuff (and that it is fun!)·I want to research what·the requirements would be.
The controller must command a "Pressure Control Solenoid Valve". The GM shop manual shows the valve is controled with a··12v PWM·signal. That solenoid, for instance, allows for a soft shift under low load, or a much harsher shift under high load
The one big question I have right now is this... Which stamp/board(s) should I consider in order to build this controller. Right now I pretty much understand (and think I can cobble together) everything but the 12v PWM signal part.·The GM shop manual states, in part...
The PCM controls the Pressure Control solenoid valve on a positive duty cycle at a fixed frequency of 292.5 Hz. A higher duty cycle provides a greater current flow through the solenoid. The high side of the valve at the PCM controls the valve operation.The PCM provides a path to ground and monitors average current and continuously varies the duty cycle to maintain the correct average current flow.
Again, thanks to the members that responded to my previous issues.
Dave
The very reason I·built my current BS2 is because after less than 15k miles (in 2 years) the TCC function got flakey and now, a problem that occured when I first got the car running is showing up again, in spades. Early on, the car would not shift into 1st and 4th. I would stop. Cycle the ignition key, and it would be OK for a day or a week. Oddly, that problem went away... until yesterday (interesting coincidence). Now its seems to be permanent.·I was never fond of that unit in any case. Found out that "TCI" markets the unit but no one there know anything about it so tech. help has always been useless. The install/user manual was cheezy, the GUI interface was primative, etc.
There is a new unit out there (PCS) but its another 850 bucks.
So now that I have found out that mere mortals can do this stuff (and that it is fun!)·I want to research what·the requirements would be.
The controller must command a "Pressure Control Solenoid Valve". The GM shop manual shows the valve is controled with a··12v PWM·signal. That solenoid, for instance, allows for a soft shift under low load, or a much harsher shift under high load
The one big question I have right now is this... Which stamp/board(s) should I consider in order to build this controller. Right now I pretty much understand (and think I can cobble together) everything but the 12v PWM signal part.·The GM shop manual states, in part...
The PCM controls the Pressure Control solenoid valve on a positive duty cycle at a fixed frequency of 292.5 Hz. A higher duty cycle provides a greater current flow through the solenoid. The high side of the valve at the PCM controls the valve operation.The PCM provides a path to ground and monitors average current and continuously varies the duty cycle to maintain the correct average current flow.
Again, thanks to the members that responded to my previous issues.
Dave
Comments
First you need will be a PWM circuit that can handle the PWM to the solenoid because the stamp will not supply the correct PWM signal directly to the solenoid, you could use the PWMPAL that parralax sells or switch to the SX or Propeller but if you want to use the BS2 then the the PWMPAL would be a way of controling the PWM then you could add a small shunt resistor to the negative side of your Driver say a Mosfet then use a 12bit A/D analog to digital controller to calculate the current used then you will know the line pressure.
It would be nice if you could find the pressures needed at different shift conditions in a manual somewhere but you can just set your PWM solenoid to say 80% duty cycle and then drive it and tell the shift solenoids to shift and then see how it feels.
Or another method would be to take a couple of Hall effect sensors and measure your motor RPM and then measure your driveshaft RPM and datalog those values to tell you how much slip you are getting at certain shift RPMs at certain Solenoid PWM values then just use that to tune it to balance of slip and smoothness of the shift feel.
I plan to work on the same project to control a 4L60E tranny in my truck when I gat my ECU EFI controller working check out our other thread....
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=192262
Great info.
Will need to research a bunch of what you said.
When will you actually be starting on your TCU? What do you plan on using·? Is it going in the '96 Riviera you mentioned? You may recall my car sports a ('96 Firebird) 4L60e too. I think we gotta stick together here!
I hate to have my car down for any length of time so I think I am going to add a temporary 'bandaid' to my BS2. Since it 'knows' vehicle speed, and since the TCI TCU is working, (other than TCC lockup and the 'A' solenoid commands), don't know why I couldn't code...
IF speed < n1 OR speed > n2 THEN HIGH A_SOLENIOD_RELAY ELSE LOW A_SOLENOID_RELAY...············ where n1 = 1-2 shift point and n2 = 3-4 shift point.
If you care to, you can see a few pic of my car here...
http://www.marthareisdorf.com/Street%20Rod%20Extraordinaire.html
Dave
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- Stephen
··· Here is a pdf of the PWMPAL hooked to a motor http://www.parallax.com/dl/docs/prod/acc/PWMPAL.pdf page 10 example 2 all you have to do is wire the solenoid where the motor is and replace the mosfet with the correct current capacity.
The PWMPAL output the PWM signal and the mosfet is what switches the 12vdc signal from the battery.
·I think you could have a shft tune on you car and then would just shift when you tell it to like at certain motor conditions like an extra MAP sensor and TPS sensor to know if you push it all the way to the floor it would kickdown like a 700R4 trannys kickdown cable works but the current would provide how much pressure is being applied but might not be needed if you use another TPS throttle position sensor then if it was say the throttle was pushed down 100% then the BS2 knows it needs a certain shift point and shift pressure because you are on it so hard, if you are in the city at say a certain throttle position and RPM then shift with less pressure. Basicaly ike I said find what is the lowest duty cycle just before it slips excessive then set that duty cycle as the minimum.
I attached a schematic of the start of a Solenoid drive and current reading controller its a start to play with. The PWMPAL is Stacked under the BS2 so it shares the same pins the mosfet takes the output from the PWMPAL and controls the 12vdc to the solenoid on the negative side. The Shunt resistor causes a very small voltage drop so you can read the voltage difference between the top and bottom then their are the two pots uses as voltage dividers to drop the 12vdc down to under 5vdc so the A/D analog to digital converter can read, then the voltage represents the current going to the solenoid. One thing the ADC8031 is only a 8bit so you might want to get a 12bit ADC so you will have a finer resolution voltage read..
You could make a very simple program of speed and RPM to shift th tranny the feadback from the current of the solenoid gives you the ability to know what the pressure is. I am not going to worry about my pressure feedback on the one I plan to build.
I have a 91 chevy pickup I·have been rebuilding for a powerfull street truck..
I hope this helps·
Post Edited (bennettdan) : 5/27/2007 5:39:44 AM GMT
NICE car!· Great pics!· I am enjoying the threads.· I wish I knew more of the subject.· Good luck.
agfa
Post Edited (agfa) : 5/27/2007 12:23:18 PM GMT
I'll be happy to add my 2 cents where ever you need it .......
signal on the PCM. the voltage was low, and tranny would not shift, turn off the ign. wait for 30 seconds and it worked fine for days. The check engine light would come on for a short period and stay off just happened to catch it down check for any stored trouble codes durning the problem or right after this code clears with cycling.
Before guessing at transmission problems, check for fluid level and have the PCM scanned for trouble codes FIRST. This guide is meant for problems that do not show up as PCM codes. Also, many problems that show up as transmission are actually PCM or electrical, and external to the transmission. Try a different PCM, and check for chafing where the cables come out of the PCM and touch the LF fenderwell.
Secondly, put a line pressure gauge ($55 shipped on Ebay, or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.500" boost valve (easy fix in pan).
R&R = Remove & Repair (or Rebuild) = Transmission must be removed to fix the problem and may have to be rebuilt or replaced.
Common failures on 4L60E, symptom -> cause -> any possible repair:
1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the trans may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product. May also have worn boost valve (can replace in the pan).
2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try replacing the TPS. Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Doublecheck by using the pressure gauge and watch for a big drop when the PCM commands 2nd gear. Worst case: poor line pressure rise (see below).
3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. Check the yellow spring inside the accum housing for breakage. Also, if the accumulator housing walls are scored, the housing must be replaced. Easy fix in the pan.
4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS.
6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get it fixed.
7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or further damage could result.
8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result.
9. No 2nd or 4th gear. 2-4 band is slipping. Servo seals may be damaged (can be fixed without removing trans. Otherwise, 2-4 band is worn out. R&R.
10. Trans shifts into gear harshly, 3rd gear starts, manual 2nd available but no 1st, no 4th, and no TCC lockup: No power to transmission, or trans is in limp-home mode. Check trans fuse underhood, and make sure transmission electrical connector is plugged in. Easy fix.
11. No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
12. No 2nd or 3rd available: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC).
14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid blockage (easy fix in pan), or TC broken (must remove trans and replace TC).
15. Horrible noise in 4th and feels like the brakes are on: overrun clutches are applying due to a cracked or leaking forward piston. Overrun clutches will be worn out after 30 seconds of this behavior. Car can be safely driven in D. R&R.
16. Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R. Also try a transmission flush with BG brand products (Firestone stocks it).
17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is broken. R&R. Try not to run or drive the car or further damage could result.
18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R.
20. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later.
21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken.
22. Transmission does not shift automatically, only manually. Swap in a known-good PCM, check wiring, check other sensors such as VSS and TPS.
23. 3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.
24. Car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.
25. Fluid leak out of the front of trans where the converter connects; partial or full loss of movement: Front pump bushing walked out. R&R. May have to replace converter also if hub is scored. Note that a leaking front seal usually means the bushing is walking out (i.e. call your local trans shop and schedule an appt.).
26. Torque converter shudder in 4th while lockup is engaged; problem goes away when the brake pedal is pressed slightly to unlock converter. Have a shop verify line pressure, and provided no valves in the TCC hydraulic circuit are worn, replace the torque converter. Also, Lubegard Shudder Fix will at least fix this for awhile. Or try a transmission flush by a shop that uses BG brand products.
27. Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS.
28. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler and cooler lines. Also could be overfiled transmission.
29. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels loaded in P, all four forward positions work fine:Internal crossleak feeding the forward clutches all the time. Most likely a cracked input housing. R&R required. Car can safely be driven gently in forward gears until the repair.
30. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts), but requires R&R. It is drivable until it breaks.
31. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.
Thanks for that long post but I guess I didn't make it clear... The (Stock OBD1) PCM does not know the transmission is even there... those wires were left dangeling. The Aftermarket TCI TCU has no trouble code reporting capability. I know there is nothing wrong with the transmission. While the TCU GUI interface indicates proper shift commands, it does not actually switch to ground (1st and 4th). In fact, I jury rigged a mom on swt (grnd to 'A' solenoid) so I can run around town, starting in 1st.
bennettdan
That post really helped alot. But it makes clear a fact I was becoming painfully aware of.
At this point I am just too much of a light weight to build a practical, dependable TCU without my car being down a long time, I mean, it is summer! So I am going to weenie out, bite the bullet and spent the 800 or so bucks and purchase the PCS TCU
www.powertraincontrolsolutions.com/content-4.html
It looks like a big improvement of the TCI version. (In fact, I have found that TCI will be discontinuing their unit and marketing PCS's TCU with their name on it.)
Then, I think I will get some of the "Electronics 101" mat'l Parallax offers, go back, and do this by the numbers.
So, at least I had one "success" so far with my "BS2 adventure'. I mounted 5 LED's (1st-2nd-3rd-4th-TCC)on the vertical part the driver's side windshield molding. Using the 'A' and 'B' solenoid circuits as input I light 'em up as I go through the gears. There is only one real reason to do anything to a street rod."High Coolness Factor". This qualifies!
I'll be back!
Why dont you use the original PCM to control the tranny?
I determined a long time ago that unless I FULLY understand the environment It's almost always a looser to try'n mix/match parts.·While any one of the above issues was probably not a show stopper, as I started adding them up the message was clear. Get a specific aftermarket controller. The problem was I got this (what I feel is a) sub-standard·unit·from TCI.
Just a whole lota guys who build street rods probably don't· rank 'dependability' as high as I do. I don't trailer my car or show it and as you know it doesn't have a fire-breather in it. But I love to drive it... locally, or trips. And dependability is paramount.·While you can drive an L without any controller at all (with 3rd as the only forward gear) it really cooks the transmission.·One failure 1000 miles from home could easily equal the cost of·the new PCS controller.
As to trying to fix the TCI unit, after studying the data on the new PCS, I guess I am just not interested. The PCS unit·appears to be such a much better unit (time will tell) that I really want to install it and play around with it.·Doesn't matter now though, they already have my 700 bucks. It has shipped and should be here mid next week.
If any of you are interested you can see the wiring diagram for the L here...
http://www.powertraincontrolsolutions.com/download/tcu/wiring/93-current-4L60E-4L70E-4L80E_harness.pdf
·While this thread has become "non-stamp"·specific,·there seems to be enough interest for me to post my results after·I install it, so I will.
BTW, if my wife were reading this over my shoulder she would say just about all the above is B******t... and that this new controller is just a new toy to add to my toybox!
Dave
I see what you are saying about the controllers, I dont know if you have tuned your PCM on your 3800 motor but their are a few aftermarket software providers to tune the PCM controlling your motor. I use DHP tuning software and like it very much check it out if you would like to tap into your PCM the link is http://65.109.52.43/PowrTunerAvailability.htm its not cheap around 400 dollars but very nice software.
What do you plan to do with the TCI unit interested in parting with it? Email me at bennettdan@bellsouth.net if you are.
Good luck with the new PCS unit.
Once I get the PCS unit up'n runn'n and I have determined just how much time/effort I want to invest in learn'n about this stuff I will make a determination about what to do with the TCI unit. Worst case... I could mail it to you on 'long term loan'. In fact, I just had a great idea! When I built the car a got 2 PCM's. I accidentally shorted out a circuit on one of them. Its the circuit that runs the fuel pump for about 5 seconds at "key on". I think the board is fine other than that. How 'bout I send the both of them to you, and fix the PCM and send it back?
Alas, the DHP stuff is all OBDII. My engine was the last ('95) of the OBDI breed. I opted for an EASE scan tool. Does not do any real performance stuff but is a good scan tool and I can tweek the typical variables.
When I started this project several years ago, if it didn't have a carburetor/distributor I didn't have a clue as to why it ran, let alone know the difference between OBDI and II. I know now that there is just a whole lot more stuff out there for OBDII engines. But it was not all bad. As a learning effort, installing this OBDI engine just had to be easier.
Sounds like a plan, I hope that your output to the fuelpump relay is just got a bad opto and not a burnt pin on the microprocessor. I will see what I can do with it.
bennettdan@bellsouth.net is my email then I will reply with my adress and we can work out some details on kind of reverse engineering the TCU controller, hey its alot more fun to build it than it is to drive it I say....but its sweet when you can say I built that myself.