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How to replace computer chip

Discussion in 'Chevy Trucks' started by mdchest, Jul 10, 2003.

  1. mdchest

    mdchest Junior Member
    Messages: 24

    I have this 98 chevy and its been shifting hard from 1st to 2nd so today i took it to a reputable transmisson repair place, they told me that the shifting hard is from the prevous owner had put in a performance chip to give it more power,,the good news was that the transmisson is fine, but i do hate the hard shifting from 1st to 2nd,,,can anybody give me some advice on how to get it shifting the way it should, any input is greatly appreciated,

    thank you ,,, mark in fla :)
  2. wyldman

    wyldman Member
    Messages: 3,265

    You cannot change the chip in that truck.96 and up have Flash EPROM's which can be reprogrammed,and do not require replacement.

    You will need a power programmer for your truck,or a GM dealer may be able to reflash the computer for you.

    The reprogramming doesn't usually make them shift that hard,so you may actually have a trans or electronic problem causing the hard shift.Does it only do it on the 1-2 shift ? If so,maybe a broken accumulator spring ?
  3. mdchest

    mdchest Junior Member
    Messages: 24

    well i did take it to the GM dealer but they were the one that said i need a new trans,,but i got kinda worried when they couldnt give me a code, so i do not trust my local GM dealer to do any repairs on my truck,,would any shop have a reprogrammer that could do this for me at a resonable price. the trans shop said that it wasnt a hypertech programmer like i had thought, but a differnent chip was put in, like i said this is a very popular transmisson business that is around U.S. wide :) thank you for your reply :)
  4. CT18fireman

    CT18fireman Banned
    Messages: 2,133

    Wyldman is correct. Although I believe you can change the shifts points on the truck this should not really make the shift hard. You do mean that it shifts more forceful right? Or does it seem not to shift as easily, such as staying in first longer? I would try to reflash the computer first and then relook at the transmission or sensors. Most of what I have seen in hard shifting is internal.
  5. mdchest

    mdchest Junior Member
    Messages: 24

    yes , it shift forceful especially if i rabbit start, it feels like someone is hitting me from behind, but after 2nd it shifts smoothly
  6. wyldman

    wyldman Member
    Messages: 3,265

    I do believe it can firm up the shifts,by raising line pressure,but I'm not positive.I know it does modify shift points.

    I don't think you can remove the chip on the newer ECM's,it should be soldered to the board.It must have been reprogrammed somehow.There are places that you can send the ECM to and they will reburn it off the truck.

    I'd still go to a GM dealer (try another one),and get it reflashed back to stock,if you believe that is the problem.I still think it may be something else.You could also check with some performance shops,as they may be able to reprogram it for you too,but probably not back to OEM GM code.
  7. CT18fireman

    CT18fireman Banned
    Messages: 2,133

    Sounds to me like an internal problem. I would still have the truck reflashed and then check the tranny again.

    Wyldman does that transmission have electronic diagnosis? I am not as up on Chevies as Fords and Dodges.
  8. wyldman

    wyldman Member
    Messages: 3,265

    You may want to check your driveshaft slip yoke for binding.It will cause the symptom you describe,like someone hit you from behind,and can feel like a harsh 1-2 shift.

    GM has a TSB on it,and they have a special grease to lube the slip yoke and the output shaft splines to prevent the problem from reoccuring.Throw in a new output seal while your in there.Can't hurt to try it,it's a lot cheaper than hauling the trans apart.
  9. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    your truck probably has a hypertech Power programmer in it. Any chance of contacting the previous owner,and getting the programmer?,you can then unload the performance program,and reinstall the stock one that is in the hypertech. The hypertech cannot be used on another truck until the stock program is reinstalled in your truck.I dont find the shifts to harsh with the PP,siply servicing the tranny will take the edge off the harsh shift for a few 1000 miles.
  10. willis3821

    willis3821 Junior Member
    from AZ
    Messages: 2

    now now before we start to replace a tranny let me say this i had the same problem with my 98 chevy 4X4 Z71. i did the same thing you did went oh sh*& now what. i went to the dealer and they said you need a new tranny and so did three other tranny shops. well they were ALL WRONG. have you replaced your battary lately and if so was the old one leaking. if not check to see if the one in there now leaks. there is a vacum box under the battary box that when your batt leaks it drops acid all over your hoses and some of the hoses run the shifting in your tranny. that is what the problem was on mine and 25 dollars later (new hoses) and the truck shifted like new again. saved me a ton of $$$$$$. lets just hope your problem is the same let me know.
  11. Arc Burn

    Arc Burn PlowSite.com Addict
    Messages: 1,138

    John is correct(as usual!)about the functioning of the Hypertech programmer which makes me wonder why the guy would have held onto it:confused: It's useless untill the first truck is brought back to stock with it.

    I had one on my 99' and you could feel a little difference but nothing to harsh.I also programmed it back to stock before i traded it in so i could at least get a couple dollars back out of it.Good luck,looks like you got lot's of things to try here:)
  12. mdchest

    mdchest Junior Member
    Messages: 24

    WOW !!!,,, thank you everybody for all the info sounds like i got alot of different options to try,,just to answer the questions,, i know the battery hasnt been changed in awhile, but do i need to take the battery out to look at the hoses or can i just pop the hook and look at it from up top or the bottom,,,thank you everyont for all the suggestions, only wish there was one quick answer for this problem lol :)