I have successfully performed the sweet j-mod on my '99 v6, and everything has seemed to work well except now the o/d light flashes. The overdrive works, and still goes on and off with the use of the button. I tried disconnecting the battery for a bit in hopes to maybe reset the computer *shrug* but that didn't do anything. Anyone here of this or have any welcome suggestions before i head to the tranny shop? Thanks for any input.
O/D flash after j-mod
- Thread starter Smokin99
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Skymarshal
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J-mod is the valve body modification for 4R70W automatic transmissions. The "J" is for Jerry, the first name of one of the engineers that made that transmission. He designed this mod to improve shift speed and firmness, which actually helps prolong the life of the tranny internals by shortening the friction time of the bands and such. Basically it consists of opening up some the holes in the valve body seperator plate, and removing return springs in the shift accumulators ( # of holes and sizes depends on year and HP handling needs ). It woke up the tranny, was fairly easy, and only had to buy appropriate drill bit, new filter, and about 12 qts. of fluid. Well worth the $50 bucks and a saturday afternoon 
. To anyone attempting this mod it's not too complicated for the mechanically inclined just be sure to read and re-read all the proper steps, and a digital camera helps also for reference photos while disassembling. I pretty sure everything is o.k with my install seeing as the o/d flashing began while I was still filling the tranny so I think ( hope ) it just needs a code reset. Hope that explains it !
. To anyone attempting this mod it's not too complicated for the mechanically inclined just be sure to read and re-read all the proper steps, and a digital camera helps also for reference photos while disassembling. I pretty sure everything is o.k with my install seeing as the o/d flashing began while I was still filling the tranny so I think ( hope ) it just needs a code reset. Hope that explains it !
ChingonStang
Member
Interesting, but I think I'll leave my Automatic transmission alone aside from regular maintence....but if it was a manual transmission...that would be a different story.
98V6 K.I.T.T.
Founding Member
I'm not totally sure, but I think it might be your transmission input shaft sensor, or something like that can't remember the exact name at this time.
The J-mod is well worth it, and one of the best things you can do to the auto trans. However now they have hand held computers that can do the same thing through your PCM. Much easier to do and you get added benefits through the use of one, sure it's more expensive but if you are into modding your car it's usually one of those must have mods.
The J-mod is well worth it, and one of the best things you can do to the auto trans. However now they have hand held computers that can do the same thing through your PCM. Much easier to do and you get added benefits through the use of one, sure it's more expensive but if you are into modding your car it's usually one of those must have mods.
see if you have thrown a code. have you noticed any slipping after performing the mod? did you reflash or chip the computer?
the J-mod and program change are not the same thing. all a tune does is increase the fluid pressure. the J-mod increases flow. the best thing is to combine the two. when i had just a tune, my car could not shift fast enough from 1st to 2nd. with the J-mod it does it in half the time.
the J-mod and program change are not the same thing. all a tune does is increase the fluid pressure. the J-mod increases flow. the best thing is to combine the two. when i had just a tune, my car could not shift fast enough from 1st to 2nd. with the J-mod it does it in half the time.
Thank you for the replies. I reset the computer by disconnecting the battery for over 30 min. and the light is still flashing. There is no slipping at all, and the quart of Lucas i dumped in there during the refill may actually be doing what it claims, but who really knows?
The light had come on during the fluid filling process. Pour in six quarts, start engine, allow to idle to cycle through while moving shifter through the gears. While doing this the car rolled about a foot and shortly after that is when I noticed the light. The tranny was only 1/2 full at this point. I'm hoping thats what set something off.
Going to get my hands on a code reader this weekend and see what comes up. This has been the only thing I've done to the car performance-wise aside form ripping the air cleaner snorkel off so far. I just bought it about a month ago, and changed out the alternator and power steering pump and slowly going through the car ( only 85,000 but i think it had sat for a bit) I'll keep ya posted on my progress.
The light had come on during the fluid filling process. Pour in six quarts, start engine, allow to idle to cycle through while moving shifter through the gears. While doing this the car rolled about a foot and shortly after that is when I noticed the light. The tranny was only 1/2 full at this point. I'm hoping thats what set something off.
Going to get my hands on a code reader this weekend and see what comes up. This has been the only thing I've done to the car performance-wise aside form ripping the air cleaner snorkel off so far. I just bought it about a month ago, and changed out the alternator and power steering pump and slowly going through the car ( only 85,000 but i think it had sat for a bit) I'll keep ya posted on my progress.
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