Anyone else heard of this? I did some searching and people on other forums(ford-trucks and fullsizebronco) confirm it. The only debate seems to be on which years are effected.

http://www.plowsite.com/threads/noti...mission.56733/

 

I don't have an automatic transmission but thanks for posting this. Very strange read, in a good way

 

I'd love to see the source of that info cause I'm not so sure I believe it.

 

Here's a couple other threads I've found. There was one on fullsizebronco but I can't find it at the moment.

http://www.ford-trucks.com/forums/69...ghts-e40d.html

http://www.thedieselstop.com/forums/...3544?_k=cit2i3

 

Following...

 

I'm going to try. How would I be able to tell it unlocks? Would it feel like it's down shifting or something?

 

I believe the torque convertor only locks in overdrive but I'm really not sure. I would expect the torque convertor to lock around 40mph. If the flashers really do prevent it from locking, I would expect rpms to go up when the flashers are on(convertor unlocked) and the rpms to go down some when the flashers are off(convertor locks up again). This may happen at lower speeds but I'm not sure. I'm a little iffy on how/when locking torque convertors work.

 

I've been curious about this for a while also, so I pulled out my manual over the weekend.

According to my manual the hazard lights have no interaction with the transmission. Neither do the turn signals nor the brake lights have anything to do with the transmission.

The only lighting circuit that has anything to do with the transmission is the reverse lights. The MLPS, when in the Reverse position, will close a circuit allowing the reverse lights to come on. Nothing internal to the transmission is connected to a lighting circuit.

What I do see is that when the Brake On/Off (BOO) switch is closed (by pressing the brake pedal), the pass-through voltage sends a signal to disengage the cruise control and to turn on the two rear brake lights as well as the third-eye brake light. This voltage is also fed into the PCM. The PCM may then use this signal in determining whether to release the torque converter clutch, or not. I don't see details on the PCM logic, but, either way, I find nothing that indicates the hazard/turn/brake/reverse lights having an affect on the torque converter clutch.

Also, since the PCM does not control any of the external lights (they have their own power/ground and switching circuits) I see no way for the PCM to gain feedback from the lights to control the TC clutch.

So, I'm calling this myth BUSTED.


PS. My books are for the 1994 F150/Bronco, so, other years/models that use the E4OD may be different, but I see no reason for them to be.

 

I have a 94 do this makes me happy. Thanks for the research!

 

The brake lights do effect the transmission. Throw some led's in without resistors and the torque converter won't lock up.