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  #1  
Old April 11th, 2019, 06:12
bestos bestos is offline
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aw4 in YJ issues

Hello

I was recommended to check in this forum. I have a 91 YJ with an AW4 conversion. Guy did it for me 5 years ago. My problem is now, the transmission is not acting correctly.

For 2 days it will shift fine from 1,2,3,4 with lockup. Then i start the vehicle, put it in D, and it stays in 4th. I can manually shift to 3 and its in 3rd, and manually shift to 1-2 and its in first.

There are only 4 wires that control it from my research. TPS signal, TPS ground, 12V battery, GND, and (12) 12V ignitions. When the vehicle was working properly, the TPS signal checked out at 0.8V to 3.8V. and both battery, ignition and gnd all good.

Yesterday it went into the mode where it does not shift. I checked the voltages again. TPS voltages to computer are same, and so is GND, batt and ignition.

I have replaced the TPS and i have two TCU and both exhibit the same random "limp mode". I cannot pull codes as this is not a cherokee.

The only other input to the TCU is the Transmission speed sensor (NOT vehicle sensor in TCase). could a bad transmission speed sensor there causing my random issues? This is not spliced like the TPS or GND or 12V signals. This is just transmission to the computer.

The transmission does feel kind of clunky when you move the shifter to DRIVE from park. The solenoids obviously work when selecting 1-2, 3, and 4. I need help. I am trying to avoid a RAD design shifter and want to get this thing right. Would hate to have RAD or go back to manual.
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  #2  
Old April 11th, 2019, 20:36
trippled trippled is offline
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Re: aw4 in YJ issues

Have you tested the power and grounds when it's acting up? How did you test them? If the TCM is not working you will still get manual 1, 3 and 4 with no lock up even if the solenoids are not powered.

If you really want to load a power or ground circuit I like to use a sealed beam headlight. If it comes on bright you know it's all good. It sounds more like an intermittent connection issue. Also try searching for the aw4 thread by kastein here. Lots of good info in there.
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  #3  
Old April 15th, 2019, 04:29
bestos bestos is offline
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Re: aw4 in YJ issues

I test the ground and power by pulling the computer and testing it through the pins. when it is not having a problem and when it is, both times the 12+ and ignition 12V and ground check out. although the battery is 12.5V an ignition is 12.1.
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Old April 15th, 2019, 05:38
Boxxyjeep Boxxyjeep is offline
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Re: aw4 in YJ issues

Yes, a failing vss can cause weird shifting issues. That guy is just some sort of hall effect sensor that produces pulses based on the speed of the output shaft. Check that sensor out, and verify that your getting a signal from it when the shaft turns. Your 12v power look fine.
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Old April 15th, 2019, 06:51
Boxxyjeep Boxxyjeep is offline
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Re: aw4 in YJ issues

To be clear my mention of vss was inaccurate. I am referring to the transmission output speed sensor. It is on the adapter between the transfer case and trans. That feller is in charge of telling the tcu how fast the output shaft of the trans is spinning.
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Old April 15th, 2019, 09:16
bestos bestos is offline
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Re: aw4 in YJ issues

i saw online that sensor is a biatch to get too. how do i test that sensor? will it output a signal if the computer is unplugged? I have to be moving to get a signal, unless i put it on jack stands i guess. what voltage range am i looking for? in all my online research, no one has given any measurements for that one.
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  #7  
Old April 15th, 2019, 10:58
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kastein kastein is offline
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Re: aw4 in YJ issues

Normally a failed output speed sensor will cause the trans to be stuck in 1st not 4th. I suspect one of two things - your NSS is faulty or your TCU is faulty or not receiving power. I would suspect TPS but you already tested it.
__________________
My yard looks like Sanford & Sons.
Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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Old April 15th, 2019, 19:10
Boxxyjeep Boxxyjeep is offline
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Re: aw4 in YJ issues

https://www.cherokeeforum.com/f2/p07...ic-aw4-219427/

Link for how its checked on the newer ones. They did change around like 97. Verify your pin outs and procedure for that gen trans

Agreed that it should fail open, but who knows. I would expect s dtc in either case if the sensor was bad.
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  #9  
Old April 16th, 2019, 03:47
bestos bestos is offline
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Re: aw4 in YJ issues

Kastein,

the NSS is not hooked up to anything in my swap to my knowlege ( i can start vehicle in D), but i will do anything, how do i test it?

I will follow the harness again and check where the guy wired the 12+ and 12 switched. I can only see the TPS wires and Gnd.
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Old April 16th, 2019, 03:53
bestos bestos is offline
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Re: aw4 in YJ issues

a new NSS is like 50 bucks, i might just buy one.
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  #11  
Old April 16th, 2019, 07:40
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Ghost Ghost is offline
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Re: aw4 in YJ issues

Quote:
Originally Posted by bestos View Post
a new NSS is like 50 bucks, i might just buy one.
You can take it apart and clean it for free....
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  #12  
Old May 13th, 2019, 10:40
bestos bestos is offline
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Re: aw4 in YJ issues

update everyone - it was the TPS. I changed it like i said above - i guess the computer was still adjusting it for the next day or so. now that it is settled, i have never had a problem yet. just wanted to give an update in case anyone ever had this problem. I am running the newer computer as well just because.
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  #13  
Old May 13th, 2019, 10:41
bestos bestos is offline
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Re: aw4 in YJ issues

edit, the first computer was the jeep computer, the 2nd computer reference was the transmission ECU.
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  #14  
Old May 20th, 2019, 18:11
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kastein kastein is offline
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Re: aw4 in YJ issues

Glad to hear it's working well!
__________________
My yard looks like Sanford & Sons.
Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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