AW4 problem

So have beena member for bit. Have searched around. Trying to take down a problem with prayers of nothing major.

The issue/history
Drove it to the store for groceries & fill-up ~3 each way. Seem to "sound wierd" like a Hissing or something. But seem to drive fine. Got back home. put it in reverse to pull inot the driveway and it did not seem to "catch" like it should/normally does. But the time I look down and reached for the shifter was moving backwards. The son drives it to school the next day. I get home from work "Why aren't you at practice?" his reply "It doesn't want to go" ( Yeah I know you try being a gear head alone in this house as well. I pray the brains I know he has pays off for him later. Otherwise he'll live at home FOREVER... that is not the problem.) I go out. Start it. High Rev to start. Settles. Will not move AT ALL. Let it warm up. Check fuild. Level OK. Color brownish-red.
Let it completely cool down. Can actually move it in the driveway briefly.
CODES SCANNED - Multiple Miss-fires, Transmission Code 0756 Solenoid B.

Repairs Recently
New battery, Starter, Positive & Negative Cables, Recent steering box brace repair, NSS has been removed/cleaned/new dielectric grease/reinstalled, Plugs, Wires, Cap, Rotor, Fuel Injectors removed new o-rings installed, throttle body cleaned, IAC cleaned, CPS replaced, Oil Changed.

Have had the Jeep 1997, 4.0, 4WD, 240K for maybe 2 months.

Appears to have been driven with very questionable routine maint.

Have been chasing multiple mis-fires.

MY CURRENT PLAN.
Buy 13-14 quarts of Dex III and drain filled 3-4 quarts at a time until I have swapped all the fuild in and add a bottle of red Lube Guard at the end.

AM I doing the right thing? Is there a vacuum line that feeds the AW4 and that was the hissing? Have found a AW4 service manual on-line but haven't found any vacuum reference, YET.

Thanks in advance sorry for the long thread.

pull the pan, look for nasties.

check solenoid resistance

spec is somewhere around here.

My guess is that you sprung a major vacuum leak (hissing/multiple misfires). There's no vacuum line to the trans, there is a vent tube. Since your plan is to drain/fill till your fluid is clean then I would start off by dropping the pan, replace the filter/screen and check the resistance of all three solenoids. The resistance should be checked with a digital meter grounded to the solenoid bracket and the positive lead to the male lead in the solenoid. The resistance should be 11-15 ohms.

It sounds like you've got more problems than a single solenoid out of range, but lets hope for the best. Changing the trans fluid is more of a preventive maintenance procedure rather than a fix all. When you've got the pan off look for debris (as stated) in the pan/oil/filter.

You might also want to check the voltage readings/smoothness of sweep at idle and WOT of your TPS and adjust the TV cable, both can cause shifting issues.

Well the first 3 quarts swap did not reveal much. And I had noticeable new/clean trans fluid on the garage floor.

Keep thinking about no vacuum hose but a vent so why would the tranny build up enough pressure to hiss. Restricted filter?

Decided to do as recommended and drop the pan and swap filter. Filter and all the remaining fluid was indeed DIRTY. Cleaned pan. Found out why there was much clean fluid on garage floor. The fill tube is TWO PIECES. Had never seen that in any post. Just all the gripes about having to deal with it. Very little debris in pan. Nothing I felt was of great issue.

Tested all the solenoids resistance. 12.9, 12.2 and 12.0. All the damn clips broke so I used very small tie wraps and the wires to make sure they ( hopefully ) stay put. Cleaned them all out good with some throttle body cleaner before re installing.

Gluing the rubber gasket I bought to the pan now. I like to use Permatex #2 and then Copper Spray a Gasket on the other side on stuff I might have to take off later. ( If it worked on my 75 Vega cam cover it will work on almost anything "modern")

Will post my final findings. Now saying three Hail Marys and four Our Fathers.

Trying to take down a problem with prayers of nothing major.

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Jeep Gremlins are from an alternate reality, they have no respect for prayers or your wallet or time limitations, LOL!

You need to attack them in stealth mode, while they are asleep! Start with checking the battery, battery cables, for corrosion, and the voltages. Check for a loose vacuum hose, especially the one from the throttle body to the MAP sensor!!!!!

Then drop the Trans pan, test all three solenoids, they should read about 14 ohms. Either sol #2 is bad, or the wire between it and the ECU has a problem.

The T-fluid plan is a good one!!

Well for the first time in four days I drove.

Shifting could have been firmer in my opinion but only 1-2 and 2-3 have really noticeable before. The 4th or OD shift I've always used the RPMs to know I was in overdrive.

Final Supplies list: 1 3/4 gallons of Super Tech marked Dexron III one rubber pan gasket from Napa, One Cork Gasket/Filter set from NAPA ( cause at $18.xx it was cheaper than just the filter), one can of throttle body cleaner, and pretty much and entire afternoon.

Thanks for the guidance/advice.

I doubt you fixed the OBD-II code problem yet.

http://nissanhelp.com/diy/obd_codes/p0756_jeep.html

If all you did was change the fluid?

Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty shift solenoid B valve
- Shift solenoid B valve harness or connectors
- Shift solenoid B valve circuit is open or shorted



When is the code detected?
ECM detected a failure in shift solenoid B Circuit (2-3 shift)
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission will not shift gears.
P0756 JEEP Description
Shift solenoid valve B is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.

Read more: http://nissanhelp.com/diy/obd_codes/p0756_jeep.html#ixzz2BCsG9KUS
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GAPANDA said:

Well for the first time in four days I drove.

Shifting could have been firmer in my opinion but only 1-2 and 2-3 have really noticeable before. The 4th or OD shift I've always used the RPMs to know I was in overdrive.

Final Supplies list: 1 3/4 gallons of Super Tech marked Dexron III one rubber pan gasket from Napa, One Cork Gasket/Filter set from NAPA ( cause at $18.xx it was cheaper than just the filter), one can of throttle body cleaner, and pretty much and entire afternoon.

Thanks for the guidance/advice.

Click to expand...