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No overdrive at times

D

dirtyjerseyjeep

NAXJA Forum User
Location
new jersey
I have a 99xj with the aw4, I had a nss code so I pulled it and cleaned it, then of course re-installed it, still no o.d. At times, I researched
The issue and some said it could be the kickdown cable, when I adjust it correctly I seem to get overdrive but when I shut off the jeep and start it back up it seems to not have od again, I'm stumped here.... Any help would be greatly appreciated. Thanks
 
No CEL or other codes?

OD is controlled by one of the solenoids in the transmission. Not that difficult to diagnose and even easier to fix.

Move this thread to OEM instead of Mod Tech, you might get more responses.
 
Have you checked your TPS out? More than likely the solenoids or the TPS, if you replace one solenoid, you might as well do all 3.If that doesn't work, You might check the TCU as well it should be located under the passenger side dash under the glove box. Source one the the JY for like 20 bucks. I know from past experiences, if you bring it to a tranny shop their likely to tell you your trans is fried. AW4s are hard to kill though, normally its either the TCU or solenoids from my experience. Even if you did both, a new pan gasket, filter, solenoids, and a used TCU will probably cost you less than $150. Most mom and pop tranny shops will sell the solenoids dirt cheap too. Just my 2 cents but I may be completely wrong. Just speaking from my past experiences.
 
The test of the overdrive is driving at 50 MPH right foot steady on the gas. Tap the break pedal with your left foot. the RPMs should rise about 300RPM. The OD is turned off by the brake switch. Here is a link to testing the solenoids.
http://www.jeepforum.com/forum/f11/aw4-solenoid-replacement-write-up-no-56k-717206/
This is quite in depth. You will be best off testing at the TCU harness, that way you are also checking the wiring as well. If you need solenoids here is a good place to purchase them. Replace all three!
http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=2&Category_Code=A340solenoid
About 230 bucks.
One thing is as the trans gets hot the solenoid may go bad so it may be best to test it hot.

Ron
 
Frank Z said:
The TCC signal goes through the Normally Closed contacts in the brake switch.

A simple adjustment to move the switch closer to the pedal arm may be all that's needed.
Click to expand...

Or a new switch. They are cheap. Actually you would want to move it the other way, farther away. And the switch is actually 2 switches, one for TCU lock/unlock signal for the TC, the other for the brake lights. You need to test the TCU side with an ohm meter or volt meter to see if the switch is bad.
 
Tapping the brake pedal unlocks the torque converter clutch, and has nothing to do with whether or not you're in OD, or more accurately fourth gear. The torque converter locks up at about 37 MPH in third, and around 42 in fourth, at least on mine, with stock gearing and normal tires. Try shifting between third and fourth, with an unlocked torque converter, to see if the RPMs change, or you feel a shift.
 
dirtyjerseyjeep said:
Okay so at 50mph when I tap the brake the rpms jump about 300rpms, could the tv cable be stretched?
Click to expand...

That would be the TC unlocking!!! Is this rig stock, and if yes, what is the engine RPM at 60 mph steady. On mine it is right at 2000 rpm in D, 4th (stock).
IF the final RPM at 60 mph is the same in 3rd as D, then you are right, it is not shifting to 4th. But note the TC may unlock and rellock in about 1-2 seconds during the shifter move from D to 3rd.

But wait, I just remebered Sol#3 is for TC lockup. Sol 1 and 2 control 1st, 2nd, 3rd and 4th. Isn't 4th when both solenoids are off by default?
 
Last edited:
I checked the manual, 4th gear both solenoids are off, it is the default gear, so if you only have 3 gears, it must be 1,2 or 3 that is missing, but Second gear requires both solenoids to be on!!! 1st requires 1 solenoid, and 3rd requires the other solenoid, so if #1 or 2 solenoid is bad you loose 2 gears!!!!

Now one possible issue is the shifter linkage, are you getting it into "D"-???
 
Last edited:
MAY POP said:
The OD is turned off by the brake switch.

Ron
Click to expand...

Correction, the TC is locked and unlocked by the TCU operating solenoid #3 to lock and unlock the Torque converter.
 
It's stock gearing on 31s, if I adjust the tv cable and drive it it will kick into od when I drive it, but as soon as I shut the jeep off and start driving it again without adjusting the cable it won't go into od, the gear shifter goes into d without a problem, I have 1,2 and 3rd gear at all times, when it doesn't kick into od at about 50 I'm doing 2300rpms, and at 60 I'm about 25-2600rpms
 
If you are having to readjust the TV cable each time, the cable position lock mechanism must be bad, or in a bind. between the AW4 and the TB?
 
heyhar said:
That sounds more like a torque converter not locking up, not failure to attain fourth gear.
Click to expand...

No it must be 4th, not the TC. Loss of TC lock is only 200 rpm, in 4th with no TC lockup he should be at about 2000 rpm. He must be in third to be at 2500 rpm with 31 tires!!!!
 
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