89 Renix AW4 TC not locking up, and no Reverse on cold start up

History:

2WD, 89 XJ, 4.0, last repair was new CPS (6 months ago), and brake light switch (3 months ago). Has cruise, but it never worked.

The AW4 has on occasion the last 15,000-20,00 miles (2 years) had some issues. One was a tail cone seal leak. The brass tail cone to drive shaft bushing is worn, and needs R&R, but the leak slowed considerably with 1/4 pint of Trans-X addition (every 6-12 months) and regular transfusions 2.5 quarts at a time. It also had a problem getting stuck in 2nd gear while in D once, about 2 years (20,000 miles ago), that went away with Trans-X addition and transfusions.

Engine and AW4 work like new during acceleration and cruising, lots of torque and power!!!! I have had this jeep for about 4-5 years now. First repair was a new head gasket, 40,000 miles ago, right after I bought it. All major tune items were replaced. Mileage is still low, under 150,000 miles total since 1989.

Problem #1:

But the engine has a slight miss at idle, that makes the idle speed drop 200-300 rpm (from 900 to 500 rpm in park, from 750 to 450 in drive) during the miss.

Problem #2:

It is also taking a longer crank time to get it to start lately. It is not a DD, so it is not used daily. We try to make sure it gets used once a week, but it has set for 2-3 weeks at times. Battery is new, crank speed is very fast, CPS voltage is very good. Fuel economy is still pretty good, still 16-18 MPG.

Problem #3:

The transmission has absolutely no reverse on cold weather start up. After several minutes of warm up, reverse suddenly works perfectly (like someone flipped a switch), no slipping. I am wondering if the NSS can cause a cold weather loss of reverse? Also, the linkage is tied together with bailing wire where the plastic ball clip assy is, as the plastic QC was damaged by a tow truck idiot about 2 years ago, who disconnected it and damaged it. The bailing wire is there to make sure the connection does not "pop off" since it is not a solid clip and hold anymore. But I may have the bailing wire too tight for cold weather???? The cold weather reverse issue start up last winter, and re-appeared last week.

My 87 had a slow to engage reverse in cold morning start ups for 4 years before it lost 1st and second gears presumably due to aged o'ring seals and internal leaks around those worn seals that kept the pistons in the valve body from getting enough pressure to engage the clutch packs.

Problem #4:

The TC no longer locks up at all!!! It use to work. This may have started right after I fixed (replaced) the lower brake light switch!!!!

With the TC lockup...that's the #3 solenoid in the trans (ask me how I know). To my knowledge there are a few things that can/will cause it to malfunction.

1) bad solenoid #3

2) bad TC

3) TPS is not right

4) something wrong in the TCU.

5) or as you are thinking possibly due to the brake switch

I'd check the TPS first.

If you have an FSM (from other posts it sounds like you do) figure out which wire is the #3 solenoid wire and check for voltage as close to the solenoid as possible (IE right outside the transmission). I had non lockup issues and I spliced a wire in a close as I could to the solenoid...then ran it to the cab. I had the scanner hooked up (there's the word no one likes it seems) and would check for voltage to the solenoid if/when it didn't lock up according to the feel of the jeep and of course the scanner saying lockup was not happening.

As far as the reverse goes...just do a quick bypass on the NSS (it can be temporary if you don't want to leave it off altogether) and then see if it goes into reverse under the same circumstances. THat may help tell you if the NSS is weird when cold or if there is another issue.

For the miss I'd try to figure out which cylinder is the culprit. Crank the jeep and then undo each fuel injector individually and see if it gets worse on any given cylinder. Since you've done the tune up items it's not likely that but I'd check your plug gaps again...I've accidentally tapped one narrower (1 I even inadvertantly closed) and it acted as you describe. ALso check the O2 sensor. I bad 02 will cause it to have a rough and/or lower idle. (I just went through that myself).

Mike, try unplugging, cleaning, checking the pins in the black and the gray connectors near the trans dipstick tube. All signals to and from the trans/TCU travel through there. Had corrosion in the gray one in my wife's XJ and cleaning it helped the early upshift issues.

Thanks. But why, or how could the NSS switch act up on reverse only when cold, and not affect starting, running, or forward gears?

If the TCU fuse is blown, what does it do in Drive? I don't a think a blown fuse, would stock reverse from working. With a blown fuse doesn't drive "D" start out in 3rd gear?

Just trying to refresh and confirm what I think I know!

043500 said:

With the TC lockup...that's the #3 solenoid in the trans (ask me how I know). To my knowledge there are a few things that can/will cause it to malfunction.

1) bad solenoid #3

2) bad TC

3) TPS is not right

4) something wrong in the TCU.

5) or as you are thinking possibly due to the brake switch

I'd check the TPS first.

If you have an FSM (from other posts it sounds like you do) figure out which wire is the #3 solenoid wire and check for voltage as close to the solenoid as possible (IE right outside the transmission). I had non lockup issues and I spliced a wire in a close as I could to the solenoid...then ran it to the cab. I had the scanner hooked up (there's the word no one likes it seems) and would check for voltage to the solenoid if/when it didn't lock up according to the feel of the jeep and of course the scanner saying lockup was not happening.

As far as the reverse goes...just do a quick bypass on the NSS (it can be temporary if you don't want to leave it off altogether) and then see if it goes into reverse under the same circumstances. THat may help tell you if the NSS is weird when cold or if there is another issue.

For the miss I'd try to figure out which cylinder is the culprit. Crank the jeep and then undo each fuel injector individually and see if it gets worse on any given cylinder. Since you've done the tune up items it's not likely that but I'd check your plug gaps again...I've accidentally tapped one narrower (1 I even inadvertantly closed) and it acted as you describe. ALso check the O2 sensor. I bad 02 will cause it to have a rough and/or lower idle. (I just went through that myself).

Click to expand...

If the TCU fuse is blown I THINK you basically have to manually shift the trans...and you lose 2nd gear and TC lockup...chances are if it was blown you'd be having more issues than you are with the trans.

And the NSS is a goofy thing. Do a temp bypass of it and rule it out as a problem.

I think it starts out in D, not third.

Update on the 89. Rough idle is back to normal idle (If there is such a thing, LOL, for a renix). Had an interesting event today with the reverse on it. It does not like to work when cold, but today about 3 pm, I tried to head home, it went right into reverse, then I put it in park for a minute or two to fiddle with some stuff, then back into R and nothing? So I recalled something I read last week, and I switch the power/comfort switch to power, and boom, I had reverse!

What does this mean?????

89 is acting like it is ready for another Dex III transfusion, and the leak must have stopped, as it is still too full (hot) since I last brought the level back up, 2500 miles or so ago. Reverse still does not like the cold weather. It got a new tire last week and replaced the fuel pressure regulator about week ago which solved some rough idle problems...it was leaking fuel into the vacuum line!

Leave it in Power mode. You're not saving gas in the Comfort mode anyway. That's why the factory eliminated the switch in 91 or so and left Power as the default.

This beast has been parked for body work and front suspension accident damage repairs the last 14 months, and is now almost a DD again, so some of the issues I was debugging in this thread may still need solving, like the power/comfort switch affecting reverse? If that was not just a coincidence!!!!

Reverse not liking cold weather.

I have fixed the brakes (new rotors mostly), still need a new brake booster (vac leak started) and the right sized bolt-brake switch-booster shaft hole combo (Old problem, prior thread, I hope the new brake booster solves that issue??? I suspect the current brake booster was the wrong year, PO BS).

Power/comfort won't affect reverse. Bypass that switch!!

Replaced the brake booster today. Now I need the correct bolt, sleeve, nuts for the brake peddle, brake light switch assy. The booster that was in this had the wrong shaft and bolt, the hole and bolt were two small a diameter. I had a thread on that about 2 years ago. Hope to find one in a JY or ???? Once I get that part, and get it back together I check the upper TC lock-unlock switch action, and location. Found out the bushing I need for the AW4 tail cone is 38 MM (seems there is 35, 38 and 40 MM, and the books do not reveal what year is which on them, so I had to pull the drive shaft and measure it. Now I can order the bushing and seal on Monday.

Looks like I need to order several orings and the tail cone AW4 gasket before I replace the bushing and shaft seal.

The brake work is all done now, finished!!!!

I fixed the TC lock up, the upper white switch above the brake peddle was out of adjustment because we installed the correct brake booster and it moved the brake peddle assy back to where it belonged, which left the TC - brake lock up switch out of range. The BB that was on this rig when I bought was the wrong one. I cleaned the guts of the TC switch first, and it is working great now.

Been digging for days now trying to find the speedometer gear shaft and output speed sensor orings I need before I pull the AW4 tail cone (2WD) off, so I can replace the rear bushing and seal that seal the driveshaft and output shaft connection in the end of the AW4 transmission. Here are my notes:

Here is what I found today:

6035709 seems to be the universal speedometer gear o'ring and

83503723 seems to be the output speed sensor oring

while some said it was obsolete, some dealers show it available online. I had to get fancy with searches after I confirmed the OEM part numbers at 3 dealers on the phone. I am told that the speedo gear and Oring is the same in the transfer case as it is in the 2WD AW4 set up, presumably from 1987 to 2001 (But that remains to be proven?). The dealers told me the speedo gear assy and oring only shows up on the OEM drawing with the transfer case, but they claim it was / is the same for the 2 WD even though the system does have a drawing for it. And the output speed sensor seems to be in the transmission on 4 and 2 WD rigs (so it should be the same), so it is the same oring there in both 2 and 4 WD. These links had at least one of the orings:


http://www.jeep4x4center.com/speedometer-pinion-o-ring-6035709.html

http://www.quadratec.com/products/55200_50.htm

http://www.4wd.com/Jeep-Drivetrain-...aspx?t_c=12&t_s=116&t_pt=8368&t_pn=JEP6035709

http://www.factorymoparparts.com/6035709.html

http://oem.factorymoparparts.com/parts-catalog

https://www.fortec4x4.com/cart.php?mode=checkout

http://www.factorychryslerparts.com/showAssembly.aspx?ukey_assembly=536865&ukey_product=4424110

http://www.factorychryslerparts.com/cart.aspx

http://www.trademotion.com/partlocator/index.cfm?siteid=214727

http://www.atascosa.com/parts/chry20.html