PCM causes shifting issue?

[LittleGiant]

I’ll keep this simple.

I’ve read a million places that the PCM can cause shifting issues. Wranglerfix says it doesn’t. So I don’t know who to believe.

I’m having a flare from 2-3 and 3-4. I have a new TCM from Wranglerfix. Have never had a code pop up.

So can the PCM cause this flaring?

 

[machoheadgames]

As I understand it, the hard shift issue related to the PCM is on 05-06 models only, which have a combined PCM/TCM, and the issue is typically the PCM incorrectly thinking the transmission is at a much higher temperature than it actually is. And I believe that hard shift only really happens going from 1-2 typically.

Your transmission hard shifting from 2-3 and 3-4 and the fact that your PCM does not control the transmission since you have an 04 (03-04 are the same), makes me think you have a transmission issue. Your year model is not known for hard shifting issues due to the PCM.

 

[twisted-pixel]

I'm sure people with more experience will chime in, but I was having 3-4 flare on my transmission (2006). Here's my findings..

ATF fluid...old ATF can cause this (what state is your ATF in?)
I changed mine...still same problem

4th gear isn’t getting enough hydraulic pressure fast enough which could be a lazy pressure control solenoid, valve body issue, or worn seals in the clutch drum.
I replaced my TCC solenoid and valve body...still same problem

The PCM *can* cause this, but unlikely. In fact Wrangler Fix says their PCM can help cure this, not cause it.
I replaced PCM...still same issue

rebuild kit for your transmission will be the next step.

In my case, I had a major seal breakdown and ATF sprayed all over the underside of the jeep (over heated ATF probably), so I have decided to replace the transmission with a remanufactured assembly (I suffered teh occasional judder in other gears too, not just the flaring from 3-4), and install a trans cooler. I'll let you know what the outcome is in a couple of days when its done

I should note that I'm also re-routing the trans cooler lines since they pass near the cats which isn't going to help cool anything down!!

 

[jjvw]

I’ll keep this simple.

I’ve read a million places that the PCM can cause shifting issues. Wranglerfix says it doesn’t. So I don’t know who to believe.

I’m having a flare from 2-3 and 3-4. I have a new TCM from Wranglerfix. Have never had a code pop up.

So can the PCM cause this flaring?

The 03-04 PCM does not control the 42rle. That is why these years have a separate TCM.

 

[machoheadgames]

The 03-04 PCM does not control the 42rle. That is why these years have a separate TCM.

I know that, and I said that.

 

[jjvw]

I know that, and I said that.

You did. I quoted the wrong post.

 

[LittleGiant]

@jjvw Thank you

 

[NashvilleTJ]

To what does the term “flare” refer? I’ve not heard that with regard to shifting.

 

[jjvw]

To what does the term “flare” refer? I’ve not heard that with regard to shifting.

It would be a cataclysmic event where it occurs with your transmission.

 

[LittleGiant]

To what does the term “flare” refer? I’ve not heard that with regard to shifting.

Most people just say the jeep slips when shipping but slipping refers to popping out of gear.

A flare is basically this…my jeep is automatic but….imagine driving a manual. As you push the clutch in you let of the gas (give and take) but imagine you push in the clutch the shift but don’t let off the gas, the engine will rev.

That’s what mine does. Before it shifts into 3rd or 4th it has about a 200-300rpm jump then shifts.