So even if we disable abs the computer is still going to look at the tone rings?Originally Posted by 06300CSRT8
So even if we disable abs the computer is still going to look at the tone rings?
Correct, the function of gear ratio check is not part of the ABS system. The tone rings are used to check for wheel spin but also for gear ratio. My math showed the new gear ratio to be closer to 4.55 (15% increase in tone ring counts)
ok so we got the 0 displacement to work, abs no longer holds the jeep back. Now to figure out the limp mode issue as the jeep still seems to be stuck in 1st or second gear. theoretically it should drive right now if you dont spin up the tires or anything, as the rear sensors are giving the same feed back as the fronts (they are jumpered to the front sensors). How ever, the jeep still doesn't seem to want to shift. I'm starting to think there is a stored TCM code that we can't reach with hp tuners, I may need starscan from the dealer to reset the TCM. Any thoughts on that one?
PM me your email address, I will email you 2.24 HP Tuner setup and you can install, read the codes, it will read all of them.
Actually 3.0 should read all of them, as well. If it doesn't see any codes, you don't have any. There is a set procedure for the trans to come out of limp mode, if you didn't attempt to change your gear ratio setting from the 4.66 you originally put in, its not going to get reset.
Even though you see no codes, use a handheld, clear DTCs, and try again.
Last edited by 06300CSRT8; 03-31-2016 at 11:58 AM.
I don't think that is right though. for every 1 rotation of the tire from factory, the pinion would turn 3.73 times and read 52 pulses. with the 5.38s the pinion now turns 5.38 times for 1 rotation of the tire and would still be looking for 52 pulses. To make up for the 60 pulses you tell the pcm that it turned 4.66 times in the 52 pulses. Because of the 8 pulses extra.
To support this, when we had superchips last year we used to get DTC's for incorrect gear ratio, until we found the math and got the 4.66 ratio. since that point the jeep drove some what normally (although tricked) and we never had the ratio codes again.
Cant stress enough, tire diameter has NOTHING to do with the diagnostic, it only has two sensors one at the axle and one at the output shaft of the trans. Tire size has no implications for this relationship that its checking. If you had a 50" tire all it does is mean the vehicle will be traveling faster at a given axle rotation, but the ratio of output shaft to axle never changes.
But I concede I do believe you are correct, So back to how I explained, for every one rotation of axle, you will have 5.38 revolutions on your output shaft, the TCM is expecting now to count 52 pulses every time the output shaft turns 5.38 times. But instead, its going to count 60. So at how many revolutions of the output shaft will the TCM see 52 pulses...when it has rotated 4.66 times.
I think you have everything correct and simply need to reset the adaptives and clear codes to get out of the hard limp mode you are in. If that doesn't work, you MUST get a code read of the trans code. Something as simple as a faulted temp sensor for the trans will put it into hard limp mode permanently until the TCM is reset.
Last edited by 06300CSRT8; 03-31-2016 at 11:59 AM.
We have turned the ABS and ESP off in the TIPM for Jeeps like that without any issues, but don't like to do it for street driven vehicles.
For 2011 and older all you need is 1 wheel speed sensor working and the abs module will spit out a valid speedometer signal on the canbus.
for 2012 and newer with a NAG1 trans you need more wheel speed sensors installed and everything calibrated exactly right or the tans module will go into limp mode. Im not sure if 2 sensors are enough or even if you tie front to back it will work. Im pretty sure the ECM is not causing your issues.
We do a whole lot of cool things with the canbus on our Jeep JK LS swaps but I haven't really wanted to mess with the ABS for safety reasons.
For sure for the older ones, 07-11, you only need the left front wheel sensor for the speedo. Which is why our 09 jk seems to have no real issues with the abs being off. With this nag1, because there is no real output shaft sensor, the trans is using rear abs sensors to cross reference and compare through algorithms with the 2 input sensors on the tranny to determin the functionality of the vehicle. It still uses the left front for the speedo which is good, but the limp mode I feel is a result of the lack of rear abs sensors. We haven't fully cleared the TCM we will get to that tonight. We're thinking that the TCM went into limp mode with the initial adjustments we made (which were not exactly what we needed) and has been stuck there ever since. If we can clear the TCM fully then the jeep should drive under normal conditions without any issues. We wont be able to do burnouts or anything in 2wd as the rear sensors wont show a valid reading compared to the input sensors on the tranny and will result in yet again another limp scenario.
Basically once we can fully clear the TCM we will know where we're at with tuning out the abs. The vehicle is rarely street driven so abs isn't really a concern
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