e4od and break electonics

[twowheelv]

Can someone explain how the brakes tie into the transmission. I have found the green wire with a red stripe coming off the break pedel and I have found a green wire with a red stripe coming off what looks like a T-connector right over the frame rail connected to the break hydrolics.

[Mr_Roboto]

When the brakes are pressed the Torque Converter Clutch (TCC) disengages.

The wire on the frame rail is probably the brake pressure switch wire which lights the "brake" light when you lose pressure in one half of the brake system.

[cdnsarguy]

I think you talking about the Cruise control shutdown/disengage via brake pressure. This is the failsafe mechanism that takes effect when brake pressure is high enough after clutch pedal/disengagement, speedo turned off manually, brake light power shutoff failed to shut off speed/cruise control.

Trans torque convertor unlocks when brake pedal is pushed also..... so it is not locked up coming to a stop.

[twowheelv]

I have been driving around with a multi meter hooked up to the wires comming out of the break peddle. When not pressed, the voltage is 12-13v. When I press them, the voltage drops to less than 1v and the break lights come on. I am guessing this is hooked up to the trans computer to tell the TCC to disengage. If I had an intermitant ground in the breaks, this should show up where I have the multi meter hooked up, Right? I am still tring to find why my TCC is disengaging when ever it wants to. By the way, the TCC still disengaged and I didn't read a drop in voltage from the break pedel sensor. [img]/ubbthreads/images/graemlins/confused.gif[/img]

[Mr_Roboto]

The computer will disengage the TCC for more than the brakes.....

Does the TCC simply unlock and stay that way or is it locking and unlocking?

[icanfixall]

I'll add one more thing that happens with these E4OD trans. As your driving along around 35 to 40 mph let off the throttle peddle and watch the tach. It will drop to idle. Now just barely touch the throttle and feel and watch the rpms come back up. This is torque converter unlock. It is normal action. It will happen every time you let off the throttle. It sure overworks the brakes too. These diesels don't have any back compression like a gasser to help with the truck slow down. Also if you just driving along and touch the brakes the torque converter will unlock even if you keep your throttle peddle at the same position. This was Fords design to keep the motor running when we come to a stop. If the torque converter didn't unlock it would stall the motor just like a standard trans truck when you don't push in the clutch. [img]/ubbthreads/images/graemlins/smokin.gif[/img]

[twowheelv]

It is locking and unlocking. I recently had the tranny rebuilt, the shop couldn't or wouldn't find the problem that causes it to unlock and lock. This is at any speed but most noticable above 45. I know the break pedel is not loose and the FIPL has been recently calibrated. I am now wondering if I am intermitantly loosing voltage to the FIPL, could that cause the TCC to disengage with out sending a code?

[Mr_Roboto]

Replace your tach sensor.

"Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50."

[twowheelv]

The tach sensor is new.

[cdnsarguy]

Check all the connections on the engine harness, including the main one on the left side of the engine to fender wiring....

Do the test....

A dead tach sender should/would send the automatic trans into a "failure management mode" (limp mode) with harsh engagements and firm shift feel and an abnormal shift schedule. It has no effect on a manual trans only the Tach readings.

Check the wires where they exit the big nut on the oil filler housing , known to short out due to bare wire.....

Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50. You can remove and clean it but usually changed later too.

You can test it too, hold it in the air away from ferrous metal, using an ohm meter lead on each wire you need DC resistance between 2000-3000 ohms.

If it fails the test return it to where ever you got it.....

[twowheelv]

My truck doesn't shift hard. It up shifts and downshifts when appropriate and it isn't reading any codes. The OD light does work but it isn't flashing.
Back to the breaks. Where is the trans computer and what is the wire that is sending info from the breaks. I would realy like to find out if that is the problem or check it off the list of "isn't the problem".

[OkieGringo]

The trans computer is behind the kick panel on drivers side. Try attaching a ground wire from the trans housing to the body sheet metal. OkieGringo