I have an SL and an SL2 both Autos and 97s. The SL is thrashed and a rattle trap but runs good and strong. The SL2 engine (twin cam), is history but trans is good. SL2 body is pristine and suspension is solid. . My Q is can I put the engine trans from SL into SL2 WITHOUT Problems? Will I have tp change harness and ecm tcm? . What am i in for? . Please direct me. . Thanks

 

Off the top of my head, the PCM will need to be swapped with the engine and tranny. 97s did not have BCMs so you get out of jail free on that one.

If the SL2 has options like power windows that the SL (not SL1) did not offer. Don't know if they used a single basic harness for all three sedans and then removed branches for nonexistent options or if maybe SL and SL1 shared and SL2 had its own. You can go digging for part nums on a site like gmpartsdirect.co , hoping to find identical part nums for things as a start.

Of course, if they are different you will run into the situation where you have options on your sl2 but no way to wire them up.

Nothing fancy about 97 dash, but compare part numbers and visually check.
I would also check PT num on TCM since it should be the identical trans. Don't remember gear ratios changing on SL1s.

That's off the top of my head.

Hopefully Octavius is still wandering the site. He has more experience with the yeses n no s of swaps....as do others

 

Well I know that the sl2 has 15" stock alloys where the sl has 14" so there maybe differing final drove ratio. . And the sl has a traction control overide button next to the rear defroster where tge sl2 does not. . The sl2 has electric windows and mirror that the sl doesnt.... IM EMBARRASED TO SAY I havent found the ecm yet and glaf about the news about a bcm cuz I have no clue what that is.! . Im old school... Have changed out a few engines and trannys on my time...and a harness or two. But never an "engine control module," and im just wondrin if time and tech has passrd me by. . Maybe im over my head.... Not a young buck anymore!

 

Indeed the final drive ratios are diff betw the trannys for SOHC and DOHC 's. But since you are swapping the tranny out of the SL along w the engine, that won't change. How they calibrate the speedometer to match wheel diameter has always been a mystery to me. If you keep the 15's on the SL2, I THINK the speedo will read correctly.

The absence of the TRAC button on the SL2 indicates it does not have Traction Control.

Disclaimer---Speculation

If you swap the harness with the engine and tranny, you MAY gain the ability to "activate" traction control since the wiring for a switch is there. You would have to locate and buy a switch panel that has the same combination of options as the SL2 + the TRAC button. In theory if you could sort out the wiring to the override switch, you might be able to jumper it and not have a switch but the Traction control would always be on. Haven't looked at the wiring diagram so I'm not sure if this will work.

Power windows and mirror

Things like this where the SL PCM was not programmed to control these options may be a real PITA. It all depends on whether the PCM used in the SL is capable of controlling these devices via a reflash. Which brings up the alternative of purchasing a used SL1 PCM which is capable of controlling all of the options and getting it flashed. The tranny programming will be the same as will the engine (SOHC). Hadn't thought of that before.

But I DID just realize if you cannot locate an SL1 harness with both of those options, you'll have to splice your branches of wiring to the SL/SL1 harness if they are not present. Not sure how the power mirror wiring is set up or how it is run to the mirror.

EDIT: 97 PCMs used by Saturn

Saturn used 4 different PCM part numbers for 1997:
1997 SOHC Manual 21023773
1997 SOHC Automatic 21923775
1997 DOHC Manual 21023774
1997 DOHC Automatic 21923776

Conclusion: The two SOHCs (SL and SL1) use a common PCM.

BCM = Body Control Module . Used in later generation of S-cars to control everything except engine and tranny control. This was done to free up the PCM for engine and tranny control.

PCM location

You must remove the upper dash pad to access the PCM, which is located on the driver's side behind the instrument cluster. It is mounted vertically.

 

Well I assumed that since they were same year and model (well nearly) that I wouldnt have to deal with this high tech stuff, well looks like Im a donkey.
. . So lets say I swap the engines & transaxles along with the ecu's, and harness can you tell me where I'll be? Running down the road without the ability to roll down the windows? Or adjust the mirrors.? . What if I dont swap the ecus? Will it work if I leave the harness in the 2 and swap ecus only? . And how do i flash? . In my day that meant rinnin around campus in ur birthday suit. . Im not sure I should swap motors... Maybe just keep the 2 for a parts car! Idk? What do you think?

 

Kinda.
Already tried to tell you where you'd be, approximately, and your basic options/paths. Success or failure ultimately involves follow up research on your part to figure out what will work and what will not work BEFORE you start. If I had definitive knowledge you'd have definitive answers.

Not sure. See above. EDITED TO INCLUDE 1997 PCM Part numbers.

Saturn apparently used 4 different PCMs for 1997:
1 each, SOHC (M/T & A/T)
1 each, DOHC (M/T & A/T)
To the best of my knowledge, If you don't swap the PCM's a DOHC PCM will not run an SOHC engine and vice versa.


No clue. harnesses would need to be the same. You will need to research this.

Dealership w their equipment.

I think that, based on the revelation that the same PCM was used for the SL and SL1 (SOHCs) means

1) you can have your SL PCM reflashed as an SL1 PCM, which will allow you to specify the power access. options that can be controlled by the PCM programming of an SL1 PCM but prob not by the programming of an SL PCM.

2) You may or may not run into issues with harnesses as we do not know if the harness of an SL (or SL1 for that matter) is identical to an SL2 harness. You already know you have SL2 options which the SL does not. The next step is for you to research the harness similarities and differences.

To me, you're going to have to open them both up and find how similar they are.

3) Guess what? I just realized that SL's aren't offered with an automatic transmission.
___________________
Conclusion: You don't even know what model of car you have but are what-if'ing me to the Valleys of Neptune. Honest mistake? Only you and The Shadow know.

The mess of complexity came in b/c the SL and SL2 had different non-options and that opened the door for the possibility of different harnesses and a whole lot more, requiring alternative planning, blah blah blah.

That, and until today, it was not clear that the PCM used was the same.

SPECULATION -- USE AT YOUR OWN RISK PENDING YOUR OWN FURTHER RESEARCH
1) Check to ensure every option you have on the SL2 was available on the SL1 in 97.
2) Then figure out if the harness in your SL1 has wiring for those options, even if not used. If missing, may have to steal from SL2 harness
3) Figure out if the SL2 harness is identical to the SL1 harness -- if so you may want to use it but wire lengths and component location differences could come into play.
4) Either swap SL1 engine tranny PCM harness or engine tranny PCM if harness is 100% compatible
5) Reflash SL1 PCM to include Sl2 options present

6) Turn the key and see if it works....good luck.

Thread closed as I have nothing else to say about the swap or the hours I spent trying to help untangle an SL-->SL2 swap mess that never existed. Apology acccepted.

Moving on with life.