ECM interchangability

Discussion in 'General Motoring' started by Son_Worshipper, Nov 14, 2006.

  1. My '93 SL2 has a high rev problem. It goes up to about 3000 in idle
    and stays there until the car comes to a complete stop. I have cleaned
    the throttle body, replaced the EGR valve, replaced the engine coolant
    sensor and connector, replaced the idle speed control module. My
    mechanic was baffled as well. The ECM doesn't tell him anything
    useful. It is our opinion that the ECM has probably gone bad. So I
    ordered one from 6th Planet - on August 28th to be exact. An ECM
    showed up on October 17. Mine was a 48 state part. The new one is a
    California part. The conector keys are different. 6th Planet has
    ignored several emails. I am not at all pleased. Question: can I
    just remove the keys and use the California part?
    Son_Worshipper, Nov 14, 2006
  2. Son_Worshipper

    Lane Guest

    6th Planet has ignored several emails. I am not at all pleased.

    Well, that's not very good business if that is the case.

    Can you post the numbers on the label on the PCM you just bought so we can
    determine its year? Generally, if the connector is different, then the
    wiring is different as well and it is NOT plug-and-play. At best, you would
    have to re-wire something, and most people would not want to attempt that.
    There is a swap guide here, but I don't know if it will tell you much about
    your current situation:

    Even if you receive a PCM that does match up for the connector & year range,
    it still usually need to be reflashed for the options that exist on your
    car. Otherwise, it may not work properly. I when through this when I
    swapped the engine & replaced the PCM in my '92.

    Personally, I'd be AMAZED if your condition was caused by something
    malfunctioning in the PCM. Watching this newsgroup for more than ten years
    and being an owner for 13+, I have never heard of anyone who reported theirs
    went bad.

    A California PCM probably has more restrictions for emissions compared to
    the federal version. I believe the CA & NY cars have additional equipment
    you may not have (air pump comes to mind, and the close-coupled cat that's
    in the exhaust manifold itself as well). I don't know this for sure, but
    I'd suspect there may be a slight mileage difference between them as well.

    Is your mechanic a Saturn tech at your local Saturn retailer? If not,
    consider taking it to them. I've found them to be well worth the diagnostic
    fee they charge because they've been dead on for all the oddball problems
    I've taken to them over the years that I was not able to diagnose myself.

    Lane [ lane (at) ]
    Lane, Nov 17, 2006
  3. Hi Lane,

    Here are the numbers from the two computers:


    21022241-21022245 21021855

    21022767 21022422

    The old one is marked PERF-MAN.

    The new one is marked PER-MAN-CAL.

    My mechanic is not a Saturn mechanic but has kept mine going for 13
    years. I will take the car to the dealer. That's a great idea.


    Son_Worshipper, Nov 20, 2006
  4. Son_Worshipper

    Lane Guest

    According to the Saturn factory parts manual...

    21021855 is for a '93 DOHC with manual trans.
    21022422 is for a '94 DOHC with manual trans w/ california emissions.

    So, looks like the numbers match what you expected.

    You may have to depend on luck-of-the-draw with the Saturn tech you get.
    The average one may tell you it is for a different year than your car and
    you can't use it. In fact, I suspect they may even say it is illegal and
    they can't help you with it because you're modifying the emissions system by
    swapping it. BUT, if you get a great tech, they will break out the factory
    service manuals and determine why the connectors are diffferent, and how
    involved it would be to modify your car's wiring to accomodate. This is
    something you could do as well if you wanted to, as the factory service
    manuals are a part you can purchase from your local Saturn's parts
    department. Or, you can see them on eBay once in a while too.

    I have some spares I keep on hand for my race car, and a quick look at the
    PCMs connectors for the '93 vs '94 show them to be the same. BUT, neither
    of mine is a CALIF so I have no idea what variable that throws into the mix.

    If I were you... I'd return it and get the correct PCM. Or, if that isn't
    an option, find the correct one elsewhere. Again, eBay is a great place to

    Good luck,
    Lane [ lane (at) ]
    Visit my Saturn Car Audio and Performance Page at

    Lane, Nov 21, 2006
  5. Son_Worshipper

    wavy Guest

    I hate to sound like a one trick pony.
    But I believe the problem is a bad Coolant temperature sensor.
    I've had the exact same problem with two consequetive Saturn SC2s.
    Thing has been a complete stumper for "professional mechanics".

    I honestly believe that this was a flaw added to the engine design so
    that every single one would be off the road 10 years after leaving the

    Without this eventual cooling induced problem - most Saturns would last
    200 to 300 thousand miles with decent care.


    PS - Is there ANYONE out there that has a working odometer past 100,000
    The instrument cluster is CRAP cheap plastic that wasnt MENT to last 10
    I went out in the junkyard to find ONE electric drive gear for the
    EIGHT were screwed up out of EIGHT that I took apart!

    General Motors - I Like the products, I HATE the company.
    wavy, Dec 1, 2006
  6. Son_Worshipper

    Lane Guest

    PS - Is there ANYONE out there that has a working odometer past 100,000
    Both of my Saturns have never had a problem with the odometer (157k on the
    '94, 148k on the '92).

    Lane [ lane (at) ]
    Lane, Dec 2, 2006
  7. Son_Worshipper

    wavy Guest

    Do you keep them indoors?
    Maybe its the Texas climate. Heat gets incredable inside a baking SC2!
    (I've measured 160.)

    PS. Never never reset the trip odometer while moving. That's what
    happened when mine stopped (a 1994) - also have heard same with older
    model Porches.

    wavy, Dec 2, 2006
  8. Son_Worshipper

    NapalmHeart Guest

    My son's car has to have 190,000+ miles on it by now. Odometer is still

    Clarksville, Michigan
    NapalmHeart, Dec 3, 2006
  9. Son_Worshipper

    Lane Guest

    The '92 I bought used, so I don't know if it was garaged but It was owned by
    a college student so I'd guess probably not.

    My '94 was kept outdoors for the first 5 years seeing -30 to 95 degrees F.
    Now it sees 30 - 95 degrees. And yes, that minus 30 is a true minus 30.
    During the outdoor years, I do remember a few windchill advisories in the
    minus 50s also. Even with those wide variations, I haven't had a problem
    with the odometers.

    Lane [ lane (at) ]
    Visit my Saturn Car Audio and Performance Page at

    Lane, Dec 3, 2006
  10. Son_Worshipper

    wavy Guest

    This is strange. I wasnt kidding about actually taking 8 units apart.
    Out of 5, BOTH the larger 15 tooth AND the smaller one were broken.
    Even the 15 tooth gear on mine fell apart after being handled too much.
    On the 3 I retained with intact 15 tooth gears, they all have cracks in
    One has a crack than runs right through the tooth - I think I'll pass
    on that one and decide on one of the other two...
    I wonder what I could do to make these questionable keepers stronger
    and last longer? Glue? Tape? Cut a new one out of a bottle cap with a
    micro file?

    It must have to do with UV and heat. I'd bet a closed Saturn attains
    temps over 100 degrees more than 6 months out of the year! Maybe
    more... I mean - far more significant killer temps down here where it
    only freezes maybe a week out of the year.

    What made removal of most of these inst clusters a lot easier was the
    fact that even the mounting plastic on these yard-cars is so brittle
    that I seldom had to unbolt them - After prying off the top dash cover
    section, I'd give the cluster a couple of yanks and break it right out.
    Crumbly, even.

    Well - Gears are available for $30 with

    wavy, Dec 3, 2006
  11. Of the last 4 cars I have had, only my '93 SL2 has NOT had this
    problem. 2 of them are Volvos! They seem to be able to bulid a car
    that can run a million miles but odometers that break at 150K. In each
    case, new gears did the trick.

    Son_Worshipper, Dec 3, 2006
  12. Son_Worshipper

    wavy Guest

    Well how about that? I would have thought if ANYone had sufficiently
    done "longevity testing" it would have been the Swedes from Volvo.
    ON THE OTHER HAND - My brother used to have an old 240 or whatever they
    called those four-door boxes... After replacing part after part at WAY
    much higher cost than Japanese or American car parts - he exclaimed to
    me that there's nothing special about Volvos that make them million
    mile cars - its just that its built so that every single tiny little
    part is individually replaceable. IE. Greater number of serviceable
    parts = more parts revenue.
    wavy, Dec 3, 2006
  13. Son_Worshipper

    BläBlä Guest

    Pfft... Work on cars for a living and you will throw that superior
    because of origin or nameplate crap out the window.
    BläBlä, Dec 3, 2006
  14. Son_Worshipper

    wavy Guest

    Well, its just that Volvo used to have a "reputation" for cars that
    lasted forever.
    Maybe it was all just a advertising ploy that "worked". I do remember
    some ads where they'd tell about some old geezer who's put like
    1,200,000 miles on his old Sedan.
    Longevity isnt sexy anymore though. If your car isnt "nearly new" you
    just aren't cool. No matter how well engineered it is.
    Oh well!

    My old aquaintances in the group 'Trout Fishing in America' toured in a
    old red Ford F-150 (named Robert, of course) for at least ten years and
    racked up close to 1,000,000 miles in it. Yeah - I dont remember
    anyone going on about how long Ford trucks last - not in a while!
    wavy, Dec 4, 2006
  15. Son_Worshipper

    BläBlä Guest

    What you or they call a reputation I call a myth. I've seen plenty of
    vehicles at near or above 1,000,000 miles of every kind and others of
    the same type ready for the junk yard before 100,000 miles. It makes
    little to no difference who makes it! It matters how often you drive,
    how you drive it, and how well you care for it!

    The people who spend big bucks buying these overpriced European cars
    usually do what with them??? They stick them in a garage every night and
    every time they have a "small" issue they go straight to the shop and
    don't mind one damn bit dishing out big bucks to get it corrected. How
    many people do you know with a Chevy that will go straight to a shop
    when the check engine light comes on? How many people with a Chevy have
    every joint greased regularly? How many people with a Chevy get a tune
    up when it's needed and not when it "no longer starts"? How many people
    with a Chevy? DO YOU GET MY POINT! My cousin has a nice low mileage
    Volvo that has been sitting for years. Why is it sitting? Because he
    doesn't want to spend more than a grand getting the rear main seal
    replaced... EOD
    BläBlä, Dec 4, 2006
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