My converter is doing very wierd things

[AintQik]

It locks when it is supposed to be unlocked and vice verses. If you drive at 55mph and take your other foot and tap the brake it locks up. Exactly the opposite of what it is supposed to do. Confirmed via TechII. Lock command unlocks, unlock locks. Could be wires or the PCM, no idea. Got the car as a basket case so I don't know if it ever worked right or not.

Does anyone have a 98PCM I could buy or borrow. I'd like to rule out the PCM as I try and figure out which wires signal the converter. I'm leaning towards wiring or PCM, but I am certainly open for advice.

I'm in Berlin by the way, S Jersey.

[NJ Torque]

What kind of converter? Stock 4L60E?

[AintQik]

The converter p/n crossed to a 3500 stall but t doesn't feel that loose. The trans is a 4l60e I have no idea if its had work. Does not feel like it. Somebody was screwing with the tune so who knows. They had all kinds of weird things changed. I had ECS'S Doug look at it and he is pretty sure nothing in the tune is doing it.

I cleaned the PCM connectors and when I plugged it back in was better but not right. I assume it is because it was learning and it is going to go right back. During that time I could not really duplicate the brake pedal thing.

[AintQik]

Wires seemed ok. If anyone can take a few readings for reference that would be cool. Pin 32 and 33 tan/brw and brown wires (pcm). Ohm between them and to ground. See what you get so I can compare.

[The_Bishop]

Stupid question, but have you checked the brake pedal switch? Might be FUBAR'd.

[NJ Torque]

I hope its not a TCI unit... high failure rates in LS1 cars.

[The_Bishop]

I'll second that. TCI is junk.

[LTb1ow]

Any misfire or similar conditions?

[AintQik]

None. I thought of that but that usually causes it to lock then immediately unlock and stay. No codes. I can command it to do what I want at will just opposite. Tip into throttle at cruise and it locks. Works perfectly just backwards. No idle issues or stoplight issues so that part seems normal.

Trying to find a PCM to troubleshoot. I'm lost.

[Jersey Mike]

TCC Lock-Up Solenoid is okay? No CEL?

[AintQik]

No CELs nothing when logged. Its an FTI converter. Only off thing I have found so far was a bit of white corrosion in the pcm plug. Not a whole lot but enuf to make me want to try and swap pcms. Losing my mind here. I'm probably going to wind up burning the tcc clurch up if I drive it.

[sweetbmxrider]

When you command lock on the tech 2, does the datastream say its locked or unlocked?

[AintQik]

Good question the tech had the techII. I'm going to hook the Solis to it tomorrow and see what it says. I was almost sure it was pressure as it would lock then release but I'm almost sure it is electrical now. I went out on 295 and held it at 70mph. It stayed unlocked. I could put my other foot on the brake and it would stay locked up till I released the brake. I can't see that as a pressure issue. I've got to get credits for this car in my HP then I might know more. I might also see something tomorrow with the solis. I don't own the techII unfortunately.

[Rob WS6]

97-98 cars should be free, at least I know for EFI Live they are. Im about 20 minutes away from you, worse comes to worse you can always drive down this way and I can load a stock tune on your PCM so at least you have a blank slate to start from.

[AintQik]

I reactivated my HPT account and dug my interface out. After hours of uploading all the updated software on the shop laptop (slow as hell) I was able to start looking at the car. The tranny tune is not stock, but nothing changed that would cause this issue. I did however save a stock tune I found in the repository for comparison and trouble shooting.

While datalogging on the way to work I was able to command the TCC sol on and off and it was acutally doing the opposite of commanded. I commanded "off" and the thing locked up and drove normal. For giggles I left it commanded "off" and the car drove right everywhere, even at stops and such locking and unlocking as it should. This leads me to almost believe its electrical. I can't see how a mech problem would cause this. Maybe the harness is fried?

So a few miles from work I unplugged HPT and the car continued to drive correctly. Wierd. I then made sure It somehow didn't command "off" permanently, which I think is impossible, and it showed no command. I then noticed that the 1-2 shift was much harsher. Light throttle would chip tires. Parked and I have not re-strted to see if the change was permanent. Driving me nuts. At this point I would be happy if it stuck and the chirping shifts don't tear the rear or tranny up. At least I can drive on a highway.

[AintQik]

On restart the symptoms are back. 1-2 shift is back to normal. I guess I need to try some tunes.

[The_Bishop]

Did you do a 'write entire' or calibration only?

[AintQik]

Bishop, i havent written anything yet.

On the way home from work I was toggling the TCC Sol off to get it to lock and drive normal. Every once in a while i would command the TCC to do something just to see what happened. It always did the opposite of what you would think as described above. While screwing with it, the SES light came on, first time for that. It was P1800 trans component slipping. Very likely becasue i was maually commanding the thing. However, as soon as the SES light came on, the trans worked perfect, with no input from me and HPT. 1-2 shift was again harsh.

[AintQik]

Found this morning that if I command the TCC Pulse Width Mod off, the converter locks as it should. I can leave the TCC Sol alone, just command the PWM off and it also works as it should. Hmmm

[AintQik]

So, still fighting. Messed with the tune a bunch and no changes. Its something in that valve body and electrics. Pinned out the PWM feed thinking that I could just short it to ground and remove the PWM from the system. Unfortunately it carries 12v on it. Shorting that to ground would be bad lol. Somehow I doubt its going to be the solenoid itself, but I will give it a shot. Slight hope that when commanded to modulate its sticking shut and not allowing fluid to the clutch. Turning it full off opens it and allows the TCC solenoid to engage the clutch... I think. If it works fine with it commanded off, maybe a new one will fix, or I can figure out how to rig it "off". I learned a lot of builders pin it "off" to prevent it from slipping the TCC. Supposed to be better for the clutch to be on or off and not slipping all the time as directed by the PWM. So, getting it full off does nto scare me and drivability with it commanded off has not really been bad. Of course my understanding could be completely wrong and it grenades in a week, but at least I will have to get a new tranny and that may result in a fix, or prove to me what i have been thinking all along that the PCM is bad

[sweetbmxrider]

Not exactly what you have going on but since you mentioned wear in the valve body:

A/T - 4L60-E Harsh 1-2 Gear Upshift/MIL/SES/CEL ON

File In Section: 07 - Transmission/Transaxle

Bulletin No.: 01-07-30-023B

Date: March, 2002

TECHNICAL
Subject:
Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set
(Replace Valve Body)

Models:
1996 Buick Roadmaster
1996 Cadillac Fleetwood
1999-2000 Cadillac Escalade
1996-2000 Chevrolet Camaro, Corvette
1996-2000 Pontiac Firebird
1996-2000 Chevrolet and GMC Light Duty Truck Models
1996-2000 Oldsmobile Bravada
with 4L60-E Automatic Transmission (RPO M30)
Built Prior to January 15, 2000 (Julian Date 0015)

This bulletin is being revised to update VIN Breakpoint Date information and revise the Parts Information table. Please discard Corporate Bulletin Number 01-07-30-023A (Section 07 - Transmission/Transaxle).

Condition

Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.

Diagnosis

Typically, these vehicles will have been driven more than 32,000 km (20,000 mi) before this condition occurs.

The scan tool may show a DTC P1870 set as a history code.

A harsh 1-2 shift or DTC P1870, caused by wear in the control valve body, may be difficult to duplicate when the transmission temperature is below 93°C (200°F).

Cause

The condition may be due to wear in the control valve body. This wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply.

Important :
^ DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code.

^ When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result.

^ This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle).

^ When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code.

^ When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL).

Correction

Install a control valve body with the revised TCC regulator and isolator valves. Refer to the Parts Information table below. These valves are used in all transmissions produced after January 15, 2000 (Julian Date 0015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.
Important : If all of the following conditions are true, it is not necessary to rebuild the transmission or to replace additional transmission components beyond the control valve body.

^ Transmission operation is normal before the transmission reaches operating temperature, or before DTC P1870 is set (no slips, flares, or missing gears).

^ The torque converter is not blue or overheated.

^ The transmission fluid is not burned or has no burned odor

^ The transmission fluid pan contains no abnormal debris (clutch material, bronze, brass, or metal fragments).

[KirkEvil]

attach and post your current tune for some of us to look at

[AintQik]

Lol, remember I didn't tune this. I havent got that far yet. Just trying to get the tranny to work right first.

Ok, small update. I know this is not a fix, but I pulled the PWM feed from the PCM, pin 33 and shorted it to ground. Trans works perfect. I get P1860 of course for the PWM circut being open, but i can tune it off. Trans will let it hit the limiter a time or 2, so I need to retune. Its got an FTI converter in it and I'm not sure if its 3k or higher.

[The_Bishop]

Took a quick look at the file. There's a little bit a weirdness as far as the force motor current tables go. Somebody boosted all the midrange numbers. As far I ever learned you don't want to screw with this table; especially if you have a shift kit in the car as the kit will increase the pressure without fudging the FMC tables.

Your shift times are zero'd out for 1-2 and 2-3, and set for .200 for 3-4, which I wouldn't do. The trans needs *some* time to complete the shifts, especially if it's stock. But with all this tinkering, the TCC maximum/minimum hasn't been changed, which it should be if you're running an aftermarket converter.

The TCC Apply/release tables have been modified to disable TCC lockup in 3rd gear. Not sure I understand why that was done. Also, all the torque management has been disabled in the transmission section which is questionable if the trans is stock.

I don't see anything standing out in the tune causing the issue. You might have a mechanical issue, such as loose valve body bolts, or a blown out valve body gasket. Could be that someone tried to put a shift kit in the trans and screwed something up, too.

[sweetbmxrider]

Originally Posted by The_Bishop

The TCC Apply/release tables have been modified to disable TCC lockup in 3rd gear. Not sure I understand why that was done.

Probably so it doesn't go into lockup running the 1/4 mile.