• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

STILL TPS & SHIFTING PROBLEMS

N

ninewon

NAXJA Forum User
Location
Seattle
STILL HAVING TPS & SHIFTING PROBLEMS

89XJ 2Dr 4L Automatic 4WD limited to make things clear.
New IAC, TPS, MAP, TCS, Cruiser54 list mostly gone through.
TPS is has less than 1ohm resistance. Input voltage on four wire plug is 4.74.
Output voltage is 3.90. There is no voltage drop from closed to wide open throttle.
NOW THE PROBLEM: Starts and runs great. SHIFTS through gears automatically WHEN COLD & during warmup. Once rig is warmed up if I'm in 3rd or ODRIVE, it randomly acts as if I shifted into 1st & engine races up. If I stop & start from a dead stop it lugs as if I had a manual trans & started out in 4th gear. I pulled the 10 amp fuse from TCU under dash on passenger side & can manual shift 1 to 3 to OD. 2nd only exists when automatic is working. No selector on shifter.

What causes it to act up when warm? Could the TPS be crap from the start. I got it from NAPA. Dealer has to outsource it so I might as well not pay their markup. Any ideas who sells quality TPS? Is this even my problem?
 
Last edited:
I have noticed that even NAPA engine sensors are not a good as they used to be. Most auto parts stores sell cheap crappy Chinese "Lifetime Warranty" parts that are often out of specification, or even failed, right out of the box. Many times they have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured with genuine Jeep repair parts.

Cheap parts are cheap for a reason.
 
This I know only two painfully. My trouble is the dealer parts guy said he would have to outsource it and it would probably come from the same parts house as Napa.
You have any sources for genuine jeep parts? The ones I've found don't carry the TPS
 
Most of the on-line Dealership Parts Departments have them, and have a 30% discount too. I have bought genuine Jeep sensors on Amazon also.
 
With no power to the TCU, 2nd exists in the 1-2 shift position but may take about 4000 rpm to shift up to second, I forget how high it needs to get. The AW4 can downshift manually from 3-2 at about 20-30 mph IIRC by shifting from 3 to 1-2 while cruising at about 30 mph

Does not sound like the TPS at all, but you need more data. I have OK service even using AZ TPS sensors on my Renix jeeps.

You should find some great test data and ideas here

http://www.naxja.org/forum/showthread.php?t=905849&highlight=Renx+files+TPS

in my old thread where I documented many TPS, ground and high idle test data points, not listed anywhere else on the internet for Renix rigs. I still even have a working OEM C-101 on 289,000 mile rig.

If you have taken care of the Intake air temp sensor (clean and test) and the ground issues, all of them, I would look at TCU and AW4 solenoid wiring next and the transmission neutral safety switch on the side of the AW4 as all the wiring to the shift solenoids, including the grounds? go through it
 
Last edited:
Tested both. But since the engine runs great and the shifting is the issue, I made final adjustments from the 4-wire.
To give a brief history: the CPS went out and ignition module. Dealer shop replaced both. Drove about a day and idle problems started. Dealer said I should change plugs. I did plugs, rotor, cap, EGR, O2 to be safe and they needed it. Still ran like crap. Since the rig has 290k & haven't had to do much, I replace MAP, IAC, TPS. Rig ran good for a week or so. Then slowly the shifting got screwy.
From a stop, I accelerate in 3 (P R N OD 3 1) and it would go but wouldn't up shift up to second automatically. I could release throttle and press again and get it to shift. Then that didn't work. Pulled the fuse for TCU & shifted manual. Worked fine. No 2nd to shift to so trani got worked a bit. Pulled trani pan & changed filter & fluid. Drove 3 days did a transfusion. Did another 2weeks later. Put the fuse back in & (presto) it shifted fine.... I'm gold!
Soon as rig warmed up BAM!!! No automatic shifting. Checked TPS somehow it was off.
I adjusted to spec on 3 wire and still no shift. Adjusted with 4 wire still.... When it warms up, no auto up shift. I tried to get to cruising speed in 3rd and put fuse in TCU and the trani would act like I downshifted to 1st.
Pulled fuse and left it out.
 
Cruiser54 suggested a solenoid test. Does anyone have an explanation on how exactly to perform this test as my manual gives no direction to perform this. Also I found on "FactoryChryslerParts" a new TPS. Tax and all $201.00.... Does that sound right?
 
Ecomike said:
With no power to the TCU, 2nd exists in the 1-2 shift position but may take about 4000 rpm to shift up to second, I forget how high it needs to get. The AW4 can downshift manually from 3-2 at about 20-30 mph IIRC by shifting from 3 to 1-2 while cruising at about 30 mph

Does not sound like the TPS at all, but you need more data. I have OK service even using AZ TPS sensors on my Renix jeeps.

You should find some great test data and ideas here

http://www.naxja.org/forum/showthread.php?t=905849&highlight=Renx+files+TPS

in my old thread where I documented many TPS, ground and high idle test data points, not listed anywhere else on the internet for Renix rigs. I still even have a working OEM C-101 on 289,000 mile rig.

If you have taken care of the Intake air temp sensor (clean and test) and the ground issues, all of them, I would look at TCU and AW4 solenoid wiring next and the transmission neutral safety switch on the side of the AW4 as all the wiring to the shift solenoids, including the grounds? go through it
Click to expand...

What are AZ TPS ?
 
ninewon said:
What are AZ TPS ?
Click to expand...

AutoZone home of the well known Dura Junk line. TPS Throttle Positition Sensor

Your problem or some of them are in the wiring and or the TRansmission. Forget the TPS, it is not your problem, if you have tried one know know good TPS from another rig, or two different vensors..

The common problems are wiring and grounds to the AW4 transmission, and the shift solenoids in the AW4, easy to access to replace from the bottom drain-filter pan. Also common is varnish build up in the valve body, but it sounds like you changed the fluid enough times already? Have you tried a little Trans-X (before you decide varnish is not the problem?).

Best thread on the transmission is "everything you ever wanted to know about the AW4" (or close to that) in this OEM section of Naxja. Awesome thread. Solenoid tests are easy. wiring issues that come and go are common and real fun to hunt for LOL
 
ninewon said:
Cruiser54 suggested a solenoid test. Does anyone have an explanation on how exactly to perform this test as my manual gives no direction to perform this. Also I found on "FactoryChryslerParts" a new TPS. Tax and all $201.00.... Does that sound right?
Click to expand...

I have 4 renix jeeps running for over 8 years all using AZ Durajunk TPS with no problems. Focus on the Solenoids and grounds to the AW4!!!! And on AW4 diagnostics. TPS is not your issue if there is a shifting issue in manual mode. That indicates varnish, or worse!!!!

I think you have a ground(s) problem still. Did you mention using the dip stick instead of the engine block ground bolt for the main ground?????

I finally moved mine to the battery post for the sensors and left only the starter ground at the block. Solved a lot of problems on the 89 rig
 
Re: STILL HAVING TPS & SHIFTING PROBLEMS

One thing I would look for is an overheating Transmission and fluid, from an exhaust leak blowing on the body of the transmission?

ninewon said:
89XJ 2Dr 4L Automatic 4WD limited to make things clear.
New IAC, TPS, MAP, TCS, Cruiser54 list mostly gone through.
TPS is has less than 1ohm resistance. Input voltage on four wire plug is 4.74.
Output voltage is 3.90. There is no voltage drop from closed to wide open throttle.
NOW THE PROBLEM: Starts and runs great. SHIFTS through gears automatically WHEN COLD & during warmup. Once rig is warmed up if I'm in 3rd or ODRIVE, it randomly acts as if I shifted into 1st & engine races up. If I stop & start from a dead stop it lugs as if I had a manual trans & started out in 4th gear. I pulled the 10 amp fuse from TCU under dash on passenger side & can manual shift 1 to 3 to OD. 2nd only exists when automatic is working. No selector on shifter.

What causes it to act up when warm? Could the TPS be crap from the start. I got it from NAPA. Dealer has to outsource it so I might as well not pay their markup. Any ideas who sells quality TPS? Is this even my problem?
Click to expand...
 
Take another look at that TV cable make sure it isn't broken. Unhook it and gently pull feel, for resistance (spring).

Haven't seen it on a Jeep, but have on some Dodges. That cable breaks, or the lever in the tranny and the pump pressure can fluctuate, which is unlikely to be a good thing.
 
Thanks for all the links & input. Finally got a day to do this. I will post outcome in a couple of hours after wrap up, test drive & tweeks.
 
Wahoo!!! Got a big 'ol fender to fender JeeP smile!!!!
First of all... Thanks to all for the ideas, threads, & links!!!:clap::clap:

So here's the breakdown: Started by Checking all my grounds.
Then went through the TCU connections under the dash & next to firewall by dipstick tube to see if clean & solid connections. Stopped short of testing the TCU itself due to not finding a thread detailing step by step instructions. So far everything Checked out.
Checked the solenoids per cruiser54 suggestion in an email. Still, all checking out to spec.
Took a lunch break to look up more ideas and keep from grabbing the BFH and smashing things.
Multiple replys to check the transmission throttle cable... Mine isn't in the best shape. The clip at the end that mounts to throttle valve arm is cracked and loose but the cable adjusted when I pushed button, pushed in, and opened throttle. Moves smoothly and I plan to replace it when the cash cow is flowing again.

The YODA Jedi force was pushing me towards the IAC, TPS, and connections, so I went there. Checked the Ohms on IAC & TPS, as well as the ground on firewall by wiggling it while reading meter. Everything was solid & .7 ohms. Probably going to redue ground cluster when I do the trans cable.

Pulled the IAC and cleaned it & where it mounts in throttle body.
Thoroughly cleaned the throttle body and butterfly.
Tested & adjusted TPS on the 3 wire plug as per Cruiser54 recommendation.
Keep in mind I've tested it for any flat spots with analog meter and it checked out. Also tested it when cold and when engine got to operating temp.
Nothing was out of place...
I'm now pulling the last two hairs on my bald head at this point:gee::gee

It must be the TCU. Sh*%^€,¥}\..... I don't have a replacement, nor could I find one. (By god I'm going to find one as a spare now)

What I did get was a new TPS, just in case, to replace my new TPS !!!
So I installed the new TPS & adjusted per the flat plug for the motor.
Started up & ran smooth as the old "new" TPS.

Went out for a test drive, so far so good. Found hills to climb, put it under heavy loads, got it piping hot.... No problems!!!!!!

What a cluster F#€¥!!! Don't know what the hell was wrong with the old"new" TPS, but problem solved!!!

Went and got some trani fluid & did a transfusion. Added some Lucas fluid stabilizer & will change out again in a few weeks to be sure.

Lesson learned.... Never skimp on parts and never rule out a new part being bad from the get go!!!
 
You must log in or register to reply here.

Similar threads

J
AW4 Problem shifting first to second when hot
Replies
2
Views
1K
cruiser54
C
P
2K IDLE - Odd Shifting - TPS? (I know.. I know)
Replies
3
Views
2K
Unclewolverine
U
C
'98 XJ p0123 help, TPS high voltage
Replies
18
Views
3K
Tim_MN
Tim_MN
A
Renix TPS nightmare
Replies
19
Views
3K
Saudade
Saudade
R
1992 XJ AW4 doesn't want to shift
2
Replies
20
Views
3K
Rob Mayercik
R
Back
Top