I'm curious if maybe my transmission isn't shifting into overdrive. I just bought the jeep, its a 98 sport 4.0 auto. All stock as far as I know. It had CEL on when I bought it... Already pulled the codes and one is a transmission code.

Anyway, it runs at like 3k rpms at 70 mph. This seems high to me... Is that normal? If not, is there some sensor that knocks the trans into overdrive that could be tripping my CEL or would the problem be more complicated than that? Thanks for the help. Sorry for typos, posting from my phone and autocorrect sucks.

 

In my '95 at 75mph I run 2100rpm. It will shift into OD at 45mph if I'm just cruising and getting on the highway won't hit OD until 55-60.

 

I had a '91...but 3000 rpm was more or less closer 85mph for me, if that helps any.

 

Use this:
www.grimmjeeper.com

 

Sounds to me like your right no o/d. My 98 did the same thing as what your explaining i just swapped out the tranny and that fixed it.

 

your torque converter sounds like it isnt locking up.

when driving up to highway speeds count the shifts.

you should feel the 1-2, then the 2-3, then the 3-4, then shortly after the third shift it should almost feel like a fourth shift, which is the torque converter locking up.

i had this issue once for a a week or so after a tranny swap. had a trouble code. it went away and everything has been fine for the next 70k miles. go figure huh.

 

From reading more sounds like it could be bad nss or tcc. I'll trying cleaning my nss and see if that helps any after work.

 

Used this tread for reference. I'm getting the two codes described here. Haven't noticed the reverse lights being out, but ill have to check that.

https://www.cherokeeforum.com/f2/che...0-p0705-60194/

 

at 65-70 i run at bout 2300rpm

 

Well I definitely wasn't shifting into overdrive. I went and cleared my CEL codes over lunch and jumped on the highway. Sure enough, no more 3000 rpms. It's down around that 2300 mark now. I know one of the codes was an o2 sensor code, so if the light gets triggered again ill read the codes and see if any that were there before are gone.

I also put a 10amp fuse in the #10 slot to see if that changes anything ( read somewhere that there's supposed to be something there, but the manual says otherwise.) I'll report back as I know more.

 

Umm... fixed it! It was missing that fuse in my fuse box. Also should note that my "dead" A/C as the previous owner put it now works. Apparently a lot rides on that little missing fuse. Worth a double check if you're having any of the following issues:

OBDII codes:

P0443
P0545
P0700
P0705
P1491

 

my od kicks in at 41-42 mph.... hibdons said the 235 rears are 20 mm wider than stock and so the speedo is a little slow, is that right ?

 

Hey which fuse box did you place the fuse

 

He said #10 in interior junction box. There's a lot of random stuff run through that fuse.