Trayson

99 XJ - 4.0L - AW4 - NP242 - 175k Miles
4" Lift, 33" Tires
Trans Fluid & Filter Changed 10k Miles ago
Owned as a DD for 18 months.

Thanks in advance for any help. It was largely because of this forum that I decided on, searched and bought the 99 XJ. Haven't had any real problems until about 2 weeks ago. The issue started very slowly and is now constant. Hope I can describe it well enough to give you an idea.

When going up a hill with the transmission in "D", moving along at highway speeds there will be an almost violent jolt felt through the entire vehicle. The jolt happens as you are increasing throttle to maintain speed going up a hill. As if it is activated by the transmission attempting to drop down into the lower gear, but it does not drop into the lower gear. If you anticipate the jolt and decrease throttle it will not happen. However you are now not maintaining speed. If you give it a strong increase in throttle it will shift down just like it should have automatically.

This started out of the blue about 2 weeks ago. It has progressed to now doing it whenever the above conditions exist (all the time). But now not just in "D". If you keep the trans in "3" it will do the same in the above conditions just not as violent a jolt.

Again if you can anticipate the jolt you can ease off the throttle and stay in the present gear or give it more throttle than necessary and it will successfully shift down.

Replaced TPS yesterday did not help.

Thanks again for any help.

cruiser54

Welcome to the Forum.

Try this:

Trayson

I should have mentioned that in OP. I have done the TV cable adjustment and toyed with it being slightly tighter and slightly more lose. No difference. It is back to the standard setting provided by the above procedure.

Something else I should have said in the original post. If I shift down manually it works perfectly.

cruiser54

Try this: http://cruiser54.com/?p=58

Trayson

Will do on the engine bay two connectors.

Concerning this paragraph . . .
"Additionally, if your Jeep is an ’87 to ’90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse."

Would I have another similar connector and fuse located some place else I could check on my 1999? Or just the two engine bay connectors?

cruiser54

I think it's under the dash above the gas pedal in yours. Not sure. Hopefully someone will chime in and verify. Definitely worth checking out.

00t444e

Sounds like it may be a slipping torque converter clutch.

cruiser54

I wonder if it has ATF-4 fluid in it instead of dex/Merc.......

Trayson

Dex/Merc because of this thread . . .
https://www.cherokeeforum.com/f2/tra...31/#post828423

Trayson

In researching my problem I ran across a thread about doing some wiring so that you could control the 1-2 gear shifting and locking in the TC. I can't find it atm but what caught my eye was he cautioned about what would happen if it shifted and you forgot to disengage the TC lock first. He actually used the word "jolt".

When the automatic shifts down to a lower gear is the TC suppose to unlock? If so what if mine is not, but staying locked? Would this cause a hard jolt?

Thanks everyone for your help.

dcollins3208

The TC should unlock; it COULD be the issue of your jolt, not saying it is. Might check your tcc solenoid, should be 11-15 ohms. Sounds like it's sticking once it warms up; but, if it was sticking all the time it would stall at idle

Tbone289

Subscribing to this one. This sounds exactly like an issue I have, but not as violent a "jolt" as the OP indicates. On mine, If you increase throttle to the point *just* before the downshift would occur, there is what feels like a "miss", not really a jolt. The RPM doesn't fluctuate, so the torque converter isn't unlocking.

It has always seems to me like the TCM is going to downshift then "decides" not to in a split second. I always figured this was due to a sensor reading with a slight fluctuation error. Maybe the TPS? Does the TCM look at TPS readings to determine when to downshift?

Trayson

I noticed something this morning because I took a different route to work. There was no problem for the first mile or three. It seemed to shift fine going up the hills and maintaining speed. Then after a few miles it started again.

I will research how to check the solenoid resistance. I think I read somewhere it's solenoid #3 wherever that is.

Thanks.

Trayson

I really have no idea how long ago mine really started. I suspect longer than I actually started noticing. It progressed to the violent jolt it could have been much milder in the beginning.

Along with what you said, mine seems to want to shift down slightly too soon when I get the jolt.

I think(?) my tach does not move before, during or after the jolt. This might suggest the same about not unlocking? I do see rpms dropping after settling into 3 or 4th gear on the upshifts.

Tbone289

My issue is minor and has been doing it for years without getting any worse. It's not a common occurrence for me to be driving hills in OD that are steep enough to require that much throttle to keep from losing RPM though.