fbody_brian

My search-fu has failed me.

I am having transmission issues and decided to have it rebuilt, but can't afford much downtime as it's my dd, so i picked up what I thought was a 94 transmission. It's not. Tag indicates 1995, and it has PWM on the pump.

What will I need to do to get this to work in my car and still have lock up?

Add a wire from the trans to the pcm and reflash it to a 95?

Do I need to change stuff in the transmission?

If I don't want PWM, what has to change?

Feel dumb for buying this thing and then finding out it's not what I thought.

01ssreda4

iTrader: (96)

Not up on those years but this may help:

https://ls1tech.com/forums/conversio...ns-4l60es.html

mrvedit

Sorry, I also don't know those years, but IIRC the TCC changed from non-PWM to PWM and the 3-2 downshift solenoid changed from PWM to non-PWM and these will affect how the PCM runs the trans.
You might try contacting builder/member Dana (handle PBA) at ProBuilt Automatics. http://www.700r4l60e.com/; he should know those years.

Unfortunately '93, '94 and '95 were transition years with all kinds of incompatible changes. After that '96 through '06 are all PCM compatible.

fbody_brian

Well I finally found the info I was looking for. Looks like I just have to disable the PWM by staking the pwm solenoid in the open position.

http://www.impalassforum.com/vBullet...d.php?t=227225

mrvedit

Excellent information. Hopefully that will work for you.

fbody_brian

Ok Here's another question that some transmission expert may be able to answer.

Looking at blocking the valve in the open position to eliminate pwm lockup, I came across this from sonnax:

Note:
Other common modifications to the TCC regulator valve in the valve body which block the valve or add a different valve/spring combination allow line pressure to apply the converter clutch at double normal converter pressures. This leads to extra force on the engine crankshaft thrust bearing and causes TCC piston flexing that – over time – leads to broken rivets and converter failure. the TCC valve and spring modification in this kit is the ONLY available modification that both eliminates PWM/eC3 operation AND regulates converter pressure to normal levels.

Question is, if you have a PWM transmission and the pcm activates the TCC lock up, when the valve is open, how is it any different than locking it open manually?

Seems that locking it open manually and electronically would lead to the same amount of pressure at the torque converter clutch.

Am I missing something here?

mrvedit

I'm barely a novice when it comes to converters, and I am a big fan of Sonnax, but let me go out on a limb and say that sounds like a rare case of BS from Sonnax.
Many (nearly all?) performance rebuilds replace the PWM TCC valve with a on/off TCC valve. From what I understand most performance converter companies even recommend that to reduce wear on their lockup clutch.
I look forward to confirmation or correction.

BTW - I didn't suggest the PWM disable of your TCC valve because I didn't know if that is all it would take.