ZJ won't shift out of 1st gear when in 4WD Low. - JeepForum.com
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Unread 07-12-2013, 10:20 PM   #1
oldZJdog95018
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ZJ won't shift out of 1st gear when in 4WD Low.

I have a 96 ZJ with the 4.0L six with the NP242 transfer case & the 42RE trans with about 140K. The transmission shifts okay when in 2wd or 4wd high, but when I put the transfer case in 4-Low the transmission won't shift out of first. I wouldn't say my transmission is in great shape. When it first starts up it takes longer to shift out of 1st than it does when it's warmed up, but I don't understand what difference it would make in 4wd high vs. 4wd low.

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Unread 07-12-2013, 11:56 PM   #2
jm8881
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4low isn't for driving around in. It's for when you need maximum torque at low speed and I don't think it will shift to second. If you drive it in 4low for anything more than like 5mph or so you're asking for trouble.
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Unread 07-13-2013, 02:50 AM   #3
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Why would u want to go faster than 5mph in 4low?

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Unread 07-13-2013, 11:05 AM   #4
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Unread 07-13-2013, 01:06 PM   #5
oldZJdog95018
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I believe that by the time you hit 5 MPH in 4WD Low it's probably already in 2nd gear getting ready to shift in to 3rd. In 4WD LOW, my transmission now stays stuck in 1st and it use to shift through all the gears before 5 ~ 7 MPH. I'm going to hop in my son's Cherokee and see if it acts the same as my ZJ. It has the same transfer-case but a different auto trans. His XJ should behave the same if i'm right and shift through the gears very quickly at a low speed.
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Unread 07-13-2013, 01:24 PM   #6
oldZJdog95018
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Quote:
Originally Posted by zjilla View Post
Why would u want to go faster than 5mph in 4low?

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The real question is the system as whole designed to shift through the gears in 4WD low. If you have chance, put you rig in 4wd on flat ground and let me know if it shifts out of 1st. my guess is it will shift to second very quick (like 2 or 3mph). I "think" something is wrong with my tranmission

just for the record, I don't drive in 4Low... it's for crawling around off road. Not my first time in the dirt, lol.
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Unread 07-13-2013, 01:45 PM   #7
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Quote:
Originally Posted by oldZJdog95018 View Post
The real question is the system as whole designed to shift through the gears in 4WD low. If you have chance, put you rig in 4wd on flat ground and let me know if it shifts out of 1st. my guess is it will shift to second very quick (like 2 or 3mph). I "think" something is wrong with my tranmission

just for the record, I don't drive in 4Low... it's for crawling around off road. Not my first time in the dirt, lol.
Full Time and Part Time use all 4 gears. They drive just the same as 2WD as far as shifting.

4-Low (As far as I know) doesn't shift through gears
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Unread 07-13-2013, 08:49 PM   #8
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I had to use 4low when my 4AT kicked off. I limped it down to the repair shop on a paved stretch of highway, going 25mph. Kept me from having to pay a hundred dollars for a tow.
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Unread 07-13-2013, 09:44 PM   #9
mrclark25
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Quote:
Originally Posted by oldZJdog95018 View Post
The real question is the system as whole designed to shift through the gears in 4WD low. If you have chance, put you rig in 4wd on flat ground and let me know if it shifts out of 1st. my guess is it will shift to second very quick (like 2 or 3mph). I "think" something is wrong with my tranmission

just for the record, I don't drive in 4Low... it's for crawling around off road. Not my first time in the dirt, lol.
my jeep does shift out of first very quickly when in 4LOW, and it does go through the gears.

i don't know how relevant that is because i have an entirely different drivetrain.
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Unread 07-14-2013, 01:04 AM   #10
oldZJdog95018
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Originally Posted by mrclark25 View Post
my jeep does shift out of first very quickly when in 4LOW, and it does go through the gears.
Yeah, I was beginning to think i was going senile. Mine use to shift through the gears too when it was in low, but the last time i was trying to get a running start on hill the engine revved way to high and it stayed stuck in first. I'm not sure what's changed or why it would happen only in 4WD low. I did a sanity check with my son's XJ this afternoon and shifts though the gears too in 4WD low like I remember mine use to.

I might try adjusting the transmission kick down cable tomorrow just see if it makes a difference, but I'm really just guessing at this point.
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Unread 07-14-2013, 05:01 AM   #11
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Quote:
Originally Posted by jm8881 View Post
4low isn't for driving around in. It's for when you need maximum torque at low speed and I don't think it will shift to second. If you drive it in 4low for anything more than like 5mph or so you're asking for trouble.
What you wrote above is 100% nonsense, and not true at all. You use 4lo when you need it, and as high speeds as you need it. The only places where you cause extra strain slamming the skinny pedal in 4lo are the axles and the TC planetary gear (+ mainshaft, which you really cannot break too easily). edit: I'm talking about wheeling here. Obviously 4lo is not meant to be used for driving around paved roads.

4lo is fine up to OD redline if you need it, ie. certain type of mudbogs or snow. I wouldn't try to redline it on dry slickrock though


I have the same problem of my tranny not coming out of 1st gear on 4lo on my niner. I have not found the reason for it - and it makes wheeling it pretty crappy at times. If it is really designed in a way that on 4lo the main tranny stays in 1st, it's really stupid.
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Unread 07-14-2013, 05:58 AM   #12
96zedjay
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A clue perhaps?
http://www.jeepforum.com/forum/f13/w...ensor-1509864/
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Unread 07-14-2013, 10:30 AM   #13
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Try manually shifting the gears. Start in 1, then shift it to 2, then D. See if that makes a difference. If not your looking possibility of trans mechanical issues. Mabye line pressure. And yes 4lo makes no difference on gear shifting. A transmission is a transmission. Made to provide different gearing. Ill us 4lo and stick it in 2nd its actually a really great giver hell combo!!!
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Unread 07-14-2013, 01:29 PM   #14
96zedjay
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Transmission shift points (and firmness) are dependent on combination of TV and governor line pressure.
Governor line pressure is controlled electronically by the PCM or TCU (year dependent). It goes by signals from the trans temp sensor and the TSS (transmission speed sensor) and/or VSS (vehicle speed sensor). The puter knows if it's in Lo or Hi range by comparing the sigs from TSS to VSS. If your TSS or wiring is bad then it will want to shift the trans at typical Hi range VEHICLE SPEED. This might be a tad hard to reach in low range.
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Unread 07-14-2013, 07:48 PM   #15
oldZJdog95018
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Quote:
Originally Posted by 96zedjay View Post
Transmission shift points (and firmness) are dependent on combination of TV and governor line pressure.
Governor line pressure is controlled electronically by the PCM or TCU (year dependent). It goes by signals from the trans temp sensor and the TSS (transmission speed sensor) and/or VSS (vehicle speed sensor). The puter knows if it's in Lo or Hi range by comparing the sigs from TSS to VSS. If your TSS or wiring is bad then it will want to shift the trans at typical Hi range VEHICLE SPEED. This might be a tad hard to reach in low range.
Thanks! I think you're on to something here.

After reading your first post I went out & found the transmission speed sensor and the connector was drenched in oil/trans fluid. I used contact cleaner to clean things up, but it didn't fix it (yet). The wires & connector look okay, but i'm going to do a continuity check out to make sure. I'm also going to try to read up on testing that TSS sensor to see if it may be bad.
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