1994 F body pcm for 1996 Y body obd II to obd I conversion?

**Lockdun1** · 09-07-2018

This is the info on the 95 to 96 4l60 I found I’m wondering if I were to do the conversion is I would be able to change the transmission control files to accept the 96 trans.

1995: Stand alone year! Will not interchange with any other year. This is a PWM transmission. An extra solenoid was added to the valve body to control the pulsed lock up strategy of the conerter clutch. It has a 12 pin case connector, extra wire in the transmission to computer harness and different computer to control the new PWM circuit. Has PWM cast in front pump. Front pump internal passages different to match new TCC strategy. 2 piece TCC control valve in valve body. Has holes in plate, marked in diagram below. 1st design 3-2 valve. 12 pin case connector. '94 computer won't recognise new TCC strategy., and will burn lock-up clutch and 3-4 clutches up. '96 computer isn't compatible with '96 3-2 control solenoid.

1996: The 3-2 downshift strategy was changed to an on /off arrangement. The TCC control solenoid was changed to a 20-31 OHM solenoid, from the previous 10-15 OHM solenoid. The 3-2 control valve was changed to the second design valve. The easiest way to identify the valve is, the second design valve will fall out as soon as the solenoid is removed. The first design has a plug and retaining clip. TCC solenoid remains 10-15 OHMs, which is the same as the '95 arrangement. Has PWM stamped cast in pump. pump is the same as '95. Will not interchange with '95 unless changing 3-2 solenoid, valvebody casting, and seperator plate. Has holes in plate marked in diagram. '94 or '95 computer will not accept the 20-31 OHM 3-2 solenoid and will throw an SES light and throw the transmission into limp mode. Some less knowledgeable builders will swap the solenoid so the computer will see the correct resistance, but the valve itself then causes downshift issues. If only the solenoid is changed, it will result in a 3-2 downshift cut loose. In other words...3-neutral-2 downshift. Speedo moved to passenger side of tail housing, but easily changed.

This is off impalaSSforum.com, I was using it to get my information, but you can never be too sure. I don't want to risk any damage.

**boshuter** · 09-07-2018

You can use the 96 tranny with a 95 bin if you use the 3-2 solenoid, valve body, and separator plate from a 95 tranny.

**Lockdun1** · 09-07-2018

Ok so as it stands now that’s my main option for the moment if I want to complete the swap. I was hoping that someone had maybe found a way to tune the issue away but if it’s my only option that’s just how it goes.

**lionelhutz** · 09-07-2018

I've been driving a car with a swapped 96 LT1/4L60e running a 95 bin flashed 8051 PCM for years now. No issues with the codes or limp mode and it downshifts just fine.

The PCM and harness came from a 94, so I added the PWM solenoid wire and re-flashed to a 95 bin.

I still have the PCM from the 96 and a home built VATS bypass. It works and can run the engine, but I've never tuned it so it's not setup right for the rear gears or tire size or engine mods.

**Lockdun1** · 09-08-2018

That is good to hear that I worked for you. It’s just from my understanding if you just swap the solenoid that valve itself is different, that It would eventually over time burn up the converter and some of the clutches.I’m going to do the resister mod on the pcm for the knock sensors and see if I dont brick the pcm flashing it. If it goes well then I plan on just spending the 250 on the 95 upgraded valvebody,plate and solenoids from sonnax and be done with it if I can’t change the pcm peramiters to accept the newer solenoid.

**Lockdun1** · 09-08-2018

Also lionelhuts, what year pwm solenoid did you use in the 96 trans?

**azxj** · 09-09-2018

I currently have a 96 Roadmaster with a 95 pcm with an auto. I did not do anything to modify the trans except install a stall converter or harness. I did however solder in the resistors on the board for the knock sensors. Seems to be working fine with the trans so far but dont have a ton of miles. It shifts fine so far and no burned fluid yet.