AW-4 not locking up

I have just put a 1993 4,0 with AW4 from a ZJ into my '86 XJ. So far the only problem (apart from the rear diff I smashed yesterday) is that the lockup never locks up. I have suspected the transmission comfort/sport switch, which I do not have and don't have a diagram for, I've also suspected the cruise control thing which I threw out. But here I got a hint about the brake switch, maybe this is what's causing the problems? Is it so that the converter will never lock up if it doesn't get a signal from the brake light switch, which I haven't connected to the engine harness, thinking it only had to do with the cruise control?

If this is the case, does anyone have a wiring diagram for it (either the brake switch or the transmission comfort/sport switch), which my Haynes books have skipped? Or an explanation of how to connect it? My books tell me where the brake switch is fed into the computer, but what is supposed to be fed? +12v when braking or not braking, or ground?

Any help is greatly appreciated.

Regards,
Amund

The brake switch must be fed into the computer, but it is not so simple. The brake switch input into the computer reads a voltage from a bias resistor (normal mode) or 12v from the brake pedal switch (unlock command).

The cruise control models share the brake pedal switch for cruise and the TCU. The CC uses the vacuum switch, and the TCU uses the electric switch on the combination switch.

The bias resistor is in the harness near the TCU (if you have the harness from a 87-90 divorced TCU).

There was Acrobat files of the AW4 manual (and FSM sections) on the Strokers and XJOG yahoogroups files sections, so someone may be able to offer a link.

Anyone?

Thanks, that cleared up a lot. I have the complete wiring harness from the 1993 ZJ my engine came from, but no switches that I've seen so far. Maybe I'll just have to go to the Jeep dealer and get that switch, or did you say that the resistor itself is somewhere in the wiring harness?

The ZJ was never equiped with a AW4 trans, that was only available in the XJ. I have worked in a Chrysler dealership for over 10 years as a trans tech so I know this as fact. The trans that was behind the 4.0 is a 42RH or 42RE.

Nope, first half of 1993 it was delivered with AW-4, at least here in Europe. I know this for a fact, I know one guy who has a 1993 ZJ with AW4, and I know mine came from one, and the filter I got for a 42RE/RH didn't fit.

Didn't notice where you were from, my mistake. you are right about the first zj's. Here in the states the AW4 was never used in the ZJ.

Okay, that explains why they're quite rare!

I've got a lot of hints so far, it seems my lockup is depending on some kind of signal/resistance from a brake switch to lock up. (This is a 1993) Does anyone have a wiring diagram for this switch, or could you point me in the right direction to where I could find it? Or maybe a jeep part number for the switch? All help is greatly appreciated.