First things first... When AEV installs new gears in a 2012+ Wrangler, we use 4.10 for 35", and 4.88 for 37". This is against common knowledge of what gear ratio works for which tires. Traditionally Wranglers were about a step and a half off from that, with the new A580 transmission some changes had to be made and most people are unaware. We see a lot of 35" owners looking to or already swapping to 4.88 when really we feel it's too low for that vehicle - UNDER MOST driving conditions. There are situations where a 2012 vehicle with 35"s probably should get 4.88 gears, but it's going to be vehicle that has a lot of off-road and very little highway use. We're trying to get the correct info out there on this, but it's slow going. Just to be clear, this is not the root of an over revving / issues, I'll get to that.
Now, to the Procal. The Procal can correct for 2012 gear ratio CHANGES. By default the TCM (transmission controller) is locked to the gear ratio the vehicle shipped with. The Procal looks at the desired gear ratio that the dip switches show, and update the few places including the 2012 TCM that gear ratio is stored. We do not change the "code" in the transmission, engine, or body controllers. Only the settings. This is what makes the Procal a Dealer Safe unit, there is never any need to restore the vehicle to default settings like there is with Superchips, Hypertec, Diablo, or other programmers. The important part here is that we can not change the way the transmission works, only the values it uses to calculate it's outputs.
Without changing these values (gear ratio and tire size as far as the TCM is concerned) once the vehicle starts to move, the TCM does a double check of all the inputs to make sure everything is working well. Every few hundred milliseconds, the TCM will look at the total vehicle speed, the left and right speeds separated, it's input shaft speed, it's current gear, and output speed, as well as static values like tire size, and gear ratio. If the all the inputs do no equal a value that is mathematically correct for the "known" gear ratio, the vehicle goes into "Limp In" mode in a few seconds. First gear is disabled, the vehicle will remain in second gear and will not shift higher than that. This will throw DTC errors like "Improper Gear Ratio First Gear" and etc. What the transmission doesn't know is that everything is fine it's just using the wrong input for Gear Ratio, rather, the transmission thinks a major fault is happening so a shut down is in order. It's a clever system to protect the vehicle/user but foolishly placed in a vehicle where gear ratio (transmission input) changes are frequent.
This is the important part... If you have changed gears in a 2012 vehicle... and you have used the Procal to define the new ratio and tire size.... and you are NOT stuck in Limp In mode (vehicle is shifting in and out of first gear)... The Procal is functioning 100% according to the software. The transmission controller is using all the correct inputs and there is no fault large enough cause a shut down error.
Now... With that out of the way the over revving or shifting issue.... I have seen it before on a couple tech calls, but have not seen it on any of our vehicles, have never seen it during 2012 Procal development, and suspect I can not recreate the issue. My best guess is that there is either a hang up in the PCM's storage of the TCM inputs, or perhaps in the TCM or TIPM as well. Any oddity issues with shifting are going to rooted in the software of the TCM (reminder, something the Procal does not change). That doesn't mean it's completely unsolvable however. If the TCM is acting up in a couple vehicles, but the overwhelmingly vast majority are working correctly, we may be able to troubleshoot the error away without having to identify it explicitly.
Before we start, I'll assume the Procal has been used to set the correct Tire Size and Gear Ratio and that the speedometer has to verified to be +/- 1mph at 65mph.
First... Unhook the battery. Unhook, then hold the Positive + Terminal to the Negative - Terminal for 10-20 seconds. This should allow for faster capacitor discharge in some circuits. Now, leave the Positive Terminal unhooked for about 20 minutes.
Second... Before hooking the Positive Terminal back up to the battery, unplug the two large connectors on the Engine Controller (PCM) under the hood. In my testing, the backup value stored in the PCM of tire size and gear ratio goes largely unused except for a couple rare situations. However, by staggering the reinitialization of the PCM (plugging it in last) it might help force an update. So, hook up the battery again, turn the key to RUN, then plug in the PCM. This is a hot-swap which normally I wouldn't recommend, except that the PCM was designed to be treated a lot rougher than a hot plug and play.
Third... with everything hooked back up again. Use the Procal to set the values again. Note: The Procal WILL NOT program the same value twice in a row. That is, if you have 34.25" tires and use the Procal to set that twice, it will honk twice, but only program on the first instance. To get the Procal to overwrite a value, a temporary value must be used first. I always recommend taking the value you have and change it by the smallest change possible. Once that is done, you can program your correct value again. So, if you have 34.25" programmed in, and want to verify it for the means on this exercise, program 34.00", turn the vehicle off, turn it back to RUN (not engine running or start) and then program 34.25" again. So do this for gear ratio and tire size.
Fourth... with the gears and tires re-set to correct values pull the battery as per step one again. 20 minutes at least. No need to stagger the PCM this time, just leave everything hooked up and let the vehicle sleep it off.
Let's start with this. I give it a 50/50 change of having no noticeable effect other than resetting your radio favorites. But that's ok, I have a second set of steps if this doesn't work. I just talked with Tim, and I'll get with Dave on a couple of things I just learned on that conversation.
jh
