AW4 Overdrive / Tourqe Convertor Issues Solved!

[XJ_Lars]

I had placed a post in this forum a few weeks back, about some trouble I was having with my AW4 jumping in and out of overdrive at 45mph & above. I thank everyone who took time to suggest possible fixes. It sounded like the TPS was the culprit, however I replaced the TPS, no luck.

I was lucky enough to take the DRB III home from work ever the weekend, and trace the problem down. The computer in the jeep was getting a signal that the brakes were being applied, and released due to a loose/faulty/old! OEM harness connector under the dash. When I was driving, this "short" would tell the computer that I was pressing brakes, and kick out the lock up tourqe convertor, causing my problem.(The truck jumping in and out of overdrive.) I am so releaved to have figured this out, and save some major $$$$ in repair & dealer troubleshooting!

I ended up simply using a few tie straps to hold the connector together tighter. If the problem continues, I'll eliminate the connector, and solder the wires.

So far...So Good!

Hope this may help anyone else who mat be expierencing the same issues.

XJ_Lars NAXJA

[5-90]

Cool - thanks for sharing!

I don't suppose you have a spare DRBII, do you? I've got enough RENIX rigs that I'm now (almost) actively looking - I've just go to have scratch handy when I find a DRBII or an MT2500...

5-90

[XJ_Lars]

Sorry 5-90... The DRBIII belongs to my work. I was suprised while using it that it really sucked! I dont know all the ins and outs, but it was very limited, even with the supercard. But hey...It worked for what I needed!

Lars :skull1:

[5-90]

Yeah - I'd prefer an MT2500, but I need something for a RE project I'm working on (in the long term.) I'd like to come up with some sort of "low-buck" alternative for reading RENIX data in real time - or maybe even something which could be mounted semi-permanently - but I need a basis for comparison first...

5-90

[scca28]

The computer in the jeep was getting a signal that the brakes were being applied, and released due to a loose/faulty/old! OEM harness connector under the dash. When I was driving, this "short" would tell the computer that I was pressing brakes, and kick out the lock up tourqe convertor, causing my problem

Good find to an annoying problem!
Which connector was it? I'd like to check mine. I did check the switches at the brake pedal, they were okay, but I never went any further. Thanks!

[XJ_Lars]

I checked the brake switch as well....wasnt the problem. If you drop the lower dash, and follow the wires that come off the stop light(brake)switch, they run towards the center(to the right) and firewall of the vehicle. I believe that it was the first connector it meets. It had about 6-8 wires on each side.

Take a look, if you cant find it, I'll climb under there and take a better look, and try to get a better discription for you.

Just let me know!
Lars:farmer:

[90xj01tj]

Dude! I have been wondering why my xj was doing just what you described and finally I have an answer. Now lets go out and see if thats the problem.

[XJ_Lars]

One good way to determine if you have the same problem, while you are driving in 4th (overdrive) reach under the dash a give the wiring a good jingle. For me, it would cause the tourqe convertor to flake out, and jump out of overdrive.

Hope this helps!

Lars:skull2:

[90xj06]

i will try that. at about 45 if you let up on the gas it downshifts and when i press the gas it up shifts. is this the same type of problem????

[5-90]

i will try that. at about 45 if you let up on the gas it downshifts and when i press the gas it up shifts. is this the same type of problem????

At 45mph, you should be either in third or fourth. In both of these ranges, Torque Converter Lockup is available (which reduces operating temperaure and increases efficiency.)

When you are not accelerating anymore, your torque converter should "lock up."

Also, when you stick your foot in it (to speed up,) the torque converter will "unlock," and your TCU should realise you're trying to speed up and downshift out of overdrive - analogous to shifting from fifth into fourth when you're trying to pass, or when you've got a long grade to climb.

I think you'll find, when you think about it, that your transmission will "upshift" (or lock up the TCC) when you let off of the skinny pedal, and "downshift" when you stick your foot in it... Both of these are normal.

5-90

[90xj06]

yes, thats what i thought but it does the exact opposite.

[Blue XJ]

Sorry 5-90... The DRBIII belongs to my work. I was suprised while using it that it really sucked! I dont know all the ins and outs, but it was very limited, even with the supercard. But hey...It worked for what I needed!

Lars :skull1:


You don't by chance work for SPX do you? I see that your in Warren, MI. I worked there for 3.5 years and dealt with the Miller Special Tools side of it quite a bit.

[90xj06]

where can you get the DRBII reader?

[Blue XJ]

where can you get the DRBII reader?



There are currently no more in stock or for sale buy the manufacturer. But if you look often eough, you can pick one up on eBay for $5-600 with the Renix adapter. Its usually about the same price on eBay for the transmission adapters as well.

[XJ_Lars]

Blue XJ - No I dont work for SPX. I work at a Video Production House, that happens to produce DC's Technical Training Videos. Thats how I got a hold of the DRBIII.