Shifting into neutral while hard braking??

I'm having a very strange problem and after searching around I have found no one that seems to have related problems

If I'm cruising coming up to a traffic light, and it changed suddenly and I brake hard, while coming to a stop the Jeep seems to downshift itself into neutral for a moment. Then once I come to a full stop it shifts back into drive. I can feel the lurch forward when it happens

Or another example. If I slowed down for the same situation. But then the light turned green and I let off the brake just before coming to a full stop, when i go for the gas it just revs, and then you can feel the shift into drive and then it operates completely normal

120k on the clock. I got the Jeep some years back and planned on doing a fluid and filter swap this coming year. The reason I haven't done it sooner is because I dont know what the PO used fluid wise when they last did the service

You could have a TC not coming out of lock up due to a bad brake switch or tps. When it finally does, you will feel a bump.

old_man said:

You could have a TC not coming out of lock up due to a bad brake switch or tps. When it finally does, you will feel a bump.

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In addition, you could have an engine running too fast. You will actually feel the down shift of the AW4 if that is the case when coming to a stop.

If you slow down enough then push the gas pedal hard, the AW4 would sometimes down shift to 1st hard enough for you to feel it.

old_man said:

You could have a TC not coming out of lock up due to a bad brake switch or tps. When it finally does, you will feel a bump.

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That's interesting. I assumed a bad brake switch meant my brake lights wouldn't work. I thought that was the only function of the brake switch.

As for the TPS, I haven't pulled any code for it, but I know that when it goes bad it doesnt necessarily pull codes. I cleaned my throttle body and IAC recently and because the tps was working fine at the time I never really touched it.

I cross posted this and other members have given me quite a few good idea. But I will investigate the TPS too along with my Kickdown cable, rear driveshaft slip yoke lubrication, and further investigate my motor and trans mount more in depth

HotBox said:

That's interesting. I assumed a bad brake switch meant my brake lights wouldn't work. I thought that was the only function of the brake switch.

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There are two separate brake switches. The lights are activated by a brown switch where the pedal meets the booster. Further up the pedal is a white switch that is normally activated and opens when you press the pedal to tell the trans to unlock. That switch is adjustable.

cal said:

There are two separate brake switches. The lights are activated by a brown switch where the pedal meets the booster. Further up the pedal is a white switch that is normally activated and opens when you press the pedal to tell the trans to unlock.

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Both my 1997 and 2001 XJ's stock brake light switch have three enclosed switches. I recently replaced the 2001's to regain the cruise control activation.

One switch powers the brakes lights.
The second switch controls the speed control's vacuum solenoid (deactivating the speed control by dumping the vacuum in the speed control's canister, when the pedal is pushed)
The third switch notifies the computer that the brake pedal has been pushed, this signal causes the computer to unlock the torque converter.

lazyxj said:

Both my 1997 and 2001 XJ's stock brake light switch have three enclosed switches. I recently replaced the 2001's to regain the cruise control activation.

One switch powers the brakes lights.
The second switch controls the speed control's vacuum solenoid (deactivating the speed control by dumping the vacuum in the speed control's canister, when the pedal is pushed)
The third switch notifies the computer that the brake pedal has been pushed, this signal causes the computer to unlock the torque converter.

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Jeeze this is total news to me. I have some more research to do and some head poking under the dash

HotBox said:

Jeeze this is total news to me. I have some more research to do and some head poking under the dash

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The wiring diagrams in the right year FSM can be a great benefit when trying to diagnose electrical issues. It shows the brake switch with it three sets of contacts.

Would a bad brake switch cause it switch or appear to switch to neutral when breaking,...braking hard verses lightly?

low fluid will cause this also

techno1154 said:

Would a bad brake switch cause it switch or appear to switch to neutral when breaking,...braking hard verses lightly?

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Yeah, thats possible, it wont actually be in neutral, but the odd timi g of the torque converting locking or unlocking might give that "felling" of going in and out of neutral.

If timing of lock up is off, id be inclined to check the brake switch first, then the throttle input and look for bad wires, connectors and such.

The AW 4 Tranny has 3 solenoids..

It is Solenoid 3 that operate the torque lock up.


Solenoids 2 and 1 operate the gear selections as there are four combinations of on or off of the two gear shift solenoids i.e.... on off, on on, off off, and off on.

Why the lock up switch on the brake pedel? You want it to unlock when you stop, else the motor will stall!

You want it to lock up properly, as the tranny ATF fluid heats up a lot if there is a lot of slippage going on in the torque converter.

Black1990jeep said:

Yeah, thats possible, it wont actually be in neutral, but the odd timi g of the torque converting locking or unlocking might give that "felling" of going in and out of neutral.

If timing of lock up is off, id be inclined to check the brake switch first, then the throttle input and look for bad wires, connectors and such.

The AW 4 Tranny has 3 solenoids..

It is Solenoid 3 that operate the torque lock up.


Solenoids 2 and 1 operate the gear selections as there are four combinations of on or off of the two gear shift solenoids i.e.... on off, on on, off off, and off on.

Why the lock up switch on the brake pedel? You want it to unlock when you stop, else the motor will stall!

You want it to lock up properly, as the tranny ATF fluid heats up a lot if there is a lot of slippage going on in the torque converter.

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I do agree with you but,... the torque converter locking and unlocking is not the same as the AW4 shifting to neutral and back to drive. The AW4 controls are a combination of mechanical and electronic. Shifting in and out of gear is mechanical. If it shifts out of gear when breaking then it would appear to me as having a mechanical problem. The electronics when working properly controls the shift points from 1 through 4 and back via solenoid 1 and 2. The third solenoid controls the torque converter lockup.

Or could the OP miss-interpret what he is feeling?

Then on second thought, the OP did mention ''hard breaking"" . Maybe the shift cable is not properly adjusted, maybe the transmission is moving because of worn or broken mounts,...