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Everything you ever wanted to know about the AW4

and the PCM uses all that data to tell the TCU when and what gear for it sift to

Not quite. The trans control unit (TCU) decides the shift points based on the output shaft speed sensor. the throttle position sensors, and input from the NSS shift sensor. It doesn't get anything from the engine computer. It doesn't need the engine computer or VSS in the xfer case. The newer AW4 also has an input speed sensor which is used to diagnose shifting problems. For example if it's commanding 3rd gear but appears to be in 2nd it will throw a code for a bad solenoid, but as far as I know it doesn't do anything different when something like this is detected.

The throttle valve cable is sometimes incorrectly called a kickdown, but as noted it only controls the hydraulic pressure and not the shift points like older non-electronic controlled transmissions. If it's not connected, you won't have enough hydraulic pressure to shift properly. It will either shift very weakly and possibly burn up clutches or just won't move at all. It comes off the drivers side, midway along the side lower down towards the pan. You actually have to remove the pan to disconnect it, so I'm surprised it's missing.

The second cable on the XJ shifter is probably the interlock cable that goes to a solenoid up near the steering wheel that actuates when you have the vehicle turned on and the brake pressed. You can remove and toss it, just beware that without the interlock setup, you'll be able to shift in/out of park without the key in and remove the key with it still in neutral or park.
 
On Renix 87-90 years one side of the TPS communicates directly with the TCU. in 1991-01 the TPS does not communicate directly with the TCU. The TPS can only communicate with the TCU in 1991-01 through the ECU. I highly suspect there are algorithms and number crunching going on that use more than just the TPS data in the ECU-PCMs to modify data from the TPS that is forwarded to the TCU.

Not quite. The trans control unit (TCU) decides the shift points based on the output shaft speed sensor. the throttle position sensors, and input from the NSS shift sensor. It doesn't get anything from the engine computer. It doesn't need the engine computer or VSS in the xfer case. The newer AW4 also has an input speed sensor which is used to diagnose shifting problems. For example if it's commanding 3rd gear but appears to be in 2nd it will throw a code for a bad solenoid, but as far as I know it doesn't do anything different when something like this is detected.

The throttle valve cable is sometimes incorrectly called a kickdown, but as noted it only controls the hydraulic pressure and not the shift points like older non-electronic controlled transmissions. If it's not connected, you won't have enough hydraulic pressure to shift properly. It will either shift very weakly and possibly burn up clutches or just won't move at all. It comes off the drivers side, midway along the side lower down towards the pan. You actually have to remove the pan to disconnect it, so I'm surprised it's missing.

The second cable on the XJ shifter is probably the interlock cable that goes to a solenoid up near the steering wheel that actuates when you have the vehicle turned on and the brake pressed. You can remove and toss it, just beware that without the interlock setup, you'll be able to shift in/out of park without the key in and remove the key with it still in neutral or park.
 
The NSS is neautral safety switch, right? I'll be deleting that. I do have the connection to the shift indicator, though. It's important to me to be able to start in gear. I also have the brake input to TCU for what I assume is torque converter unlock?

So I need to figure out the throttle valve cable to the carb linkage, and a TPS.

Until the TPS gets sorted out I can go full auto, but need the throttle valve cable for even full manual?

Okay. Need a trip to junkyard!
 
On Renix 87-90 years one side of the TPS communicates directly with the TCU. in 1991-01 the TPS does not communicate directly with the TCU. The TPS can only communicate with the TCU in 1991-01 through the ECU. I highly suspect there are algorithms and number crunching going on that use more than just the TPS data in the ECU-PCMs to modify data from the TPS that is forwarded to the TCU.

Yes, Renix erea used a dual output TPS (with the voltages running opposite each other). Later years it was a single output on the TPS. If you look at the wiring diagram the output from the single output TPS and the wiring from the trans computer go to the same pins on the engine computer connector. The trans computer is seeing the same input as the engine computer. The engine computer isn't doing anything to the TPS signal going to the trans computer.
 
Ecomike, you replied while I was typing.

My TCU has a pinout for TPS input. I planned on supplying a ground and 5VDC to TPS, then taking the sense off the TPSto TCU. Does that not work it out?
 
The NSS is neautral safety switch, right? I'll be deleting that. I do have the connection to the shift indicator, though. It's important to me to be able to start in gear. I also have the brake input to TCU for what I assume is torque converter unlock?

So I need to figure out the throttle valve cable to the carb linkage, and a TPS.

Until the TPS gets sorted out I can go full auto, but need the throttle valve cable for even full manual?

Okay. Need a trip to junkyard!

The NSS and range position sensor are the same unit, generally called the NSS. The trans computer uses the input from this to determine what position the shifter is in and that's the switch for the backup lights too, so don't eliminate it. You can skip hooking up the wires for starter interlock though. Yes the brake light switch is used to unlock the torque converter.

My TCU has a pinout for TPS input. I planned on supplying a ground and 5VDC to TPS, then taking the sense off the TPS to TCU. Does that not work it out?

Yes that works just fine. The TPS normally gets the +5v and ground from the engine computer, and you can tie into any of the other sensor wiring that has a +5v and ground signal. Connect that sensor ground to sensor ground on the TPS as well.

PM me if you need a copy of the portion of the FSM that shows the stock 99 trans computer wiring.
 
Actually, I opened up the TCU and tapped off the 12v, put in a 5v regulator circuit, and then ran it to an unused pin, so there is now a 5v for the TPS in my TCU. I'm using the TCU case as mounting and heat sink for the regulator.

My NSS is definitely wired into my harness. I have just deleted the starter disable.

So I just need throttle valve cable and TPS now. Thanks.

And I didn't mean to clutter this thread up. Sorry. Also, I'll PM you if any more issues. Thanks.
 
Actually, I opened up the TCU and tapped off the 12v, put in a 5v regulator circuit, and then ran it to an unused pin, so there is now a 5v for the TPS in my TCU. I'm using the TCU case as mounting and heat sink for the regulator.

That works too :}. A LM7805 would have been pretty simply to shove in there.
 
Okay. Sorry, but one more odd but specific question;

On the throttle where the throttle valve cable connects there is the arm that moves opposite the throttle pedal cable. I need to make a piece to adapt for that. Could someone tell me the length of that, from the pivot point to the center of the cable connector? I just need to know the radius on that so I have the correct throw. Thanks.
 
I will take your word for it then, since you know this stuff so well, and I know you do, but I heard the other version somewhere ages ago, FWIW.

Yes, Renix erea used a dual output TPS (with the voltages running opposite each other). Later years it was a single output on the TPS. If you look at the wiring diagram the output from the single output TPS and the wiring from the trans computer go to the same pins on the engine computer connector. The trans computer is seeing the same input as the engine computer. The engine computer isn't doing anything to the TPS signal going to the trans computer.
 
Okay. Sorry, but one more odd but specific question;

On the throttle where the throttle valve cable connects there is the arm that moves opposite the throttle pedal cable. I need to make a piece to adapt for that. Could someone tell me the length of that, from the pivot point to the center of the cable connector? I just need to know the radius on that so I have the correct throw. Thanks.


Looking at my 89, the radius of the arm is 1-1/8". Total pull on the cable from closed to wot is 1-1/4". In the closed position the arm is perpendicular to the cable. That's a 98 aw4 and a 89 throttle body.
 
I have a 1990 2 door Cherokee 4.0 automatic small lift kit. I am trying to remove the transfer case to rebuild it everywhere I've read says there is 6 bolts that hold the transfer case to the adapter I have searched around this thing over and over I can only find 5. Can anyone verify There is five and not sex and also if there is only 5 how the heck can you get it separated I currently have a very large come-along wrapped around the transfer case and the rear end and I've cranked on it so hard that I bent the handle on my come along. I see the case wiggle but it does not separate. Obviously this is my first time ever removing a transfer case I'm a 48 year-old disabled vet and this day just whooped my rear. Lol
 
Sorry to say, there is no sex, but there is six!
 
Yeah, lawsoncl is right. Always six on these. Since it's an auto... Pull the two 18mm bolts that hold the trans mount onto the trans tailhousing. Bet you see the missing tcase nut as soon as you remove the mount.

Guess how I figured THAT out? :looney: I didn't get as far as a comealong but I sure yanked and shook that bastard for a while before I checked under the mount.
 
I got a question. So I have a 95 242 that was mated to a aw4 from same year. I'm trying to convert a 2000 2wd to 4wd. I bought the newer 99 trans because of electronics but now the tcase is the problem. The sensor on the 95 is different from the one on the 99. Can I just change the gear or pickup deal from the output shaft? As long as splines are good will this work or do I need to find a tcase from a 99-01
 
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