SNIDELYWHIPLASH

Does your TCU look like the one in this post? It should.
https://www.cherokeeforum.com/f2/whe...61/#post411091

Here are the two side by side:
http://www.naxja.org/forum/showpost....2&postcount=11

inlinepower

the plug on the wiring harness is grey and the one one the tcu is green so ide say its the wrong one in it, i know someone changed it at one point it was missing one of the nuts that hold it on, also theres another plug on the harness with two wires on it one yellow and ones blue w/ yellow stripe and it has a jumper wire connecting the two is that supposed to be like that? sorry for all the questions but this is my first renix cherokee and im not familier with them and it doesnt help someone severly molested everything you possibly could on it so im just tryin to straighten it all out, thanks for all the help

inlinepower

need some help... got a new tcu put it in, new tps put it in, trans still stays in first gear, i found every way to adjust the tps and the voltage mine shows is always way off than what it should be, i was under the jeep the other day and noticed that the wires behind the bracket for the t-case shift linkage are all ripped out and the t-case wires too, is that my problem? im gunna try to fix them tonight and see what happedns, or do you guys think i have other issues? all help is appreciated thanks keith

freegdr

fixing the wire cant make it any worse

redmuck

is the tps brand new? or did you get it from the jy?

excess650

I don't know much about 88s, but the AW4 with TCU disconnected or FUSE out or blown should get you reverse in R, 1st in 1-2, 3rd in 3 and OD in D. It should not downsift from OD to 3, or 3-2 by itself. If you are in 1-2 and run the revs up to 4500 it should pressure shift to 2nd and then downshift again as the revs drop. If its working this way, your trans may well be OK mechanically, but having electrical control problems.

You already know about the TCU, and it needs to be adjusted to correct voltages. There may be a vehicle speed sensor on the tail housing of the trans, a kickdown cable hooked to the throttle body linkage and a brake pedal switch that unlocks the torque converter.

If R doesn't work properly hot and cold, with and without the TCU, there IS an internal problem.

There are (3) solenoids in the trans. S1 and S2 are shift solenoids and S3 is the lockup solenoid. All can be measured through the female 7 pin connector by the trans dipstick tube. With reference to ground, all should show 12-18 ohms resistance.

I have both the AW4 manual and AW4 troubleshooting manuals on my pc and can email them as attachments. The troubleshooting manual is pretty detailed and repetitive so as to make troubleshooting easier for someone unfamiliar with the workings of the auto trans.

inlinepower

the tps is new, with the old one in it it would show no voltage, with the new one in it has voltage readings but not what they should be and unable to adjust the to what they need to be, with the tcu i can unplug it and shist manually and it all seems ok except reverse when its could it wont go into it, and when its hot it has a few second delay, i think its a wiring problem as of now, all the wires going to the trans are ripped out so im going out to fix them now and see what happens

inlinepower

ok well some good news, the broken wires there was a plug on the topish of the tail shaft area with two wires i reconected those and the two wire plug on the t-case and it shifts through are the gears nicely, must be the speed sensor is my guess? so i massed with the tps some more and its only getting 4.6v input not 5v, and i got the 4.2v output wich the dirrections i was useing said is what to adjust it to, seems to shift and run better now

these are the dirrections i used

THROTTLE POSITION SENSOR (TPS)

1) Turn ignition on. Check throttle position sensor input
voltage. Connect voltmeter negative lead to terminal "B" (M/T), or
terminal "D" (A/T) of sensor connector. Connect voltmeter positive
lead to terminal "A" (M/T and A/T) of sensor connector.



NOTE:

• On (A/T) models, connector terminals are identified by
  letters molded into back of connector. On all models, do not
  disconnect TPS harness connector. Insert voltmeter test
  leads through back of wire harness connector. On some
  models, it may be necessary to remove throttle body from
  intake manifold to gain access to sensor wire harness.

2) Move and close throttle plate completely (M/T and A/T).
Ensure throttle linkage contacts stop. Note voltmeter reading. Input
voltage at terminals "B" and "A" (M/T), or terminals "A" and "D"
(A/T) should be 5 volts.

3) Return throttle plate to closed throttle position (M/T
and A/T). Check sensor output voltage. To do so, disconnect voltmeter
positive lead from terminal "A" and connect it to terminal "C" (M/T),
or terminal "B" (A/T).

4) Maintain throttle plate in closed position (M/T and A/T).
Ensure throttle linkage contacts stop. Note voltmeter reading. Output
voltage should be .8 volt (M/T), or 4.2 volts (A/T).

5) If output voltage is incorrect, loosen bottom sensor
retaining screw and pivot sensor in adjustment slot for a coarse
adjustment. Loosen top sensor retaining screw for fine adjustments.
Tighten screws after adjustment.

so my question now is why an i only getting 4.6v at the input?

SNIDELYWHIPLASH

Sounds like you're on the right track there...

The input current should be 5.0, but it isn't always. 4.6 is not uncommon. It could be due to old, faulty wiring... bad grounds somewhere, etc.

The important thing now is that your output current needs to be 83 percent of the input current, so your target voltage should be as close to 3.818 as you can get it (4.6 x .83 = 3.818)

http://autorepair.about.com/library/faqs/bl232i.htm

inlinepower

ok ill adjust the output to 3.818, also ever since i put the new tps in when its cold in the morning, it wont start unless i unplug the tps. the after its running i can plug it back in and runs ok then once its hot it will start with it pluged in is that because its out of adjustment or somthing else?

inlinepower

also if you hit the throttle hard off idle it will fall on its face then sputter and rev up any ideas on what that is? sorry for all the questions but just trying to get this thing running good

inlinepower

the jeep actually runs better with the tps unplugged is it a wiring problem?

89xjcj