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Strange trans issue

benXJ

NAXJA Forum User
Location
Raleigh, NC
96 XJ, 4.0, AW4, 4x4

I have 30x9.5in tires

While running 70 mph (on the speedo) my rpms are showing 2000...this has been the case for ever...

Now, since about 6 months ago, about half the time i get 2200 rpm showing at 70 mph. Sometimes I'll be going down the hiway, see that the rpms are reading high, slow down or come to a stop, start back and now I'm getting 2000 rpm. This is true for all speeds...I'll get 2-300 rpms higher than I should, and if I slow down for a stoplight or slow traffic, and then speed back up, I'll then get normal RPM readings.

Now, sometimes speeding up and slowing down doesn't change anything, and I'll get the same (normal) RPM readings for the entire trip, or sometimes I'll get higher RPM readings for an entire trip.

Trans is full with reddish/pink fluid. 60K miles on trans flush (whole 13 qts)

any ideas what could be causing the higher RPMs?
 
Sounds like torque convertor lockup. If the brake light switch is activated, the TC will unlock causing the jump in rpms. You may have a bad switch. Have someone watch to see if the brake lights come on. You also could be fighting a bad (dirty) neutral safety switch.
 
Sounds like torque convertor lockup. If the brake light switch is activated, the TC will unlock causing the jump in rpms. You may have a bad switch. Have someone watch to see if the brake lights come on. You also could be fighting a bad (dirty) neutral safety switch.
Agreed. Definetly TC lock up not happening, so a bad wiring issue, bad brake switch or sticking switch or solenoid #3 is bad in the AW4.
 
thanks

Brake lights are not on...I can see the third brake light from the drivers seat, they are not coming on while driving, and there is no noticable drag on the drivetrain.

The NSS will cause symptoms like this? I've had NSS issues before, and that caused no reverse lights and no start in park, but that was on an older cherokee (93), no issues like that with my current cherokee.

This happens when the ac and/or defrost is not on
 
Check the brake fuse under the hood... I had that pop once on mine and it stopped brake lights from working and caused brake light to be illuminated
 
As seems to be a popular problem today, the problem could stem from a funky Throttle Position Sensor. One of the things the TPS could affect is torque converter lock-up. Although, in my experience, the lock-up problem would come and go, no rhyme or reason. Odd shifting throughout all the gears usually accompanied it, though. As you're going to find out, '96 was a fun year! I don't think they had all the bugs worked out of OBDII yet.

My '96 will usually show 2000 RPM right at 65 MPH, as will our other three XJs. But, occasionally, my '96 will show up to 2250, and will remain slightly elevated throughout the trip. Next time, it'll be back at 2k. Go figure. But, it's been behaving good lately, so I'll put up with a little inaccuracy. Using my GPS to check the speedo, it consistently shows about 1 MPH faster, and it seems steady, so I'm just glad it's running properly.
 
thanks

Brake lights are not on...I can see the third brake light from the drivers seat, they are not coming on while driving, and there is no noticable drag on the drivetrain.

The NSS will cause symptoms like this? I've had NSS issues before, and that caused no reverse lights and no start in park, but that was on an older cherokee (93), no issues like that with my current cherokee.

This happens when the ac and/or defrost is not on

Note that the brake lights are on a separate switch. It is a dual switch, so one side could be OK, the other side bad!!!!
 
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