E40d TCC question CRAZY STUFF

[BBB]

Hello new to forum have looked over some posts about tcc but none quite like my problem, 92 f 250 4x4 7.3 idi e4od start and warm truck few minutes head out on the road tcc locks up fine for 5 to 6 miles then when I stop at intersection and get back up to speed no lockup at all no shudder slip nothing, does not work until cooled again then repeats symptons grounded the purple with yellow stripe wire to activate tcc again works cold not warmed up. trans has around 40,000 miles on it fluids good works great except this. crazy as it sounds its almost like the TOT is working backwards allowing it to come on when cold then opening switch when hot ????? Hoping someone has had this and fixed it thanks for forum lots of good info

BBB

 

[OLDBULL8]

You can check out the TOT. Between the two Yellow wires in the harness, with an Ohm meter. Cold between 32*F & 58*F the resistance is 37K to 58K, at 159*F to 194*F the resistance is 2.7K to 5K, in other words the hotter the TOT is the lower the resistance. Make sure the connector on the pass side of the trans. is plugged in all the way and the wires are not shorted or corroded. To unplug it, just squeeze the latches and pull up on the wires, DO NOT use a screw driver to pry it up, the latches will break off. There is a heat shield next to the connector, make sure it's always there, has to be removed to disconnect.

Edit: It's been known that the solder joints on the CCC solenoid are bad on the solenoid pack.

 

[FORDF250HDXLT]

lol that's kinda funny.iv not heard of one acting in this manner before.well that's cool you grounded the wire directly so you know the converter locks when you do that,cold or warm,so you've eliminated a mechanical failure.so something is going on with the control unit not telling the trans to lock up.
Bill's got ya headed the right direction,by testing the tot.......iv got a chart here somewhere too i think......

 

[BBB]

well thanks both of ya actually it doesnt work manually when warm thats the bad part nothing not even a shudder but it is so specific does same thing every time no veriation I will check the tot and see what I come up with I guess next step will be the actual TCC solenoid ???

 

[FORDF250HDXLT]

oh i see.i misunderstood then.well then,that's not so good.that eliminates the TOT sensor as being the issue.because grounding the TCCS wire yourself bypasses what the control unit commands.
hopefully you find something simple like a bad connection at the solenoid pack plug.

 

[LCAM-01XA]

Looks like an issue with the solenoid pack. All solenoids receive power from the TCM relay, not the TCM itself, so as long as some of them are working that means power into the solenoid pack is good. Manually grounding the lockup solenoid should cause the converter to lock regardess of what the TCM wants to do, that's why the TCM can get so pissy if you have a manual override switch for it installed. So basically if power in is know to be good, and manual ground is also known to be good but only effective while fluid is cold, this tells me something goes wrong with the lockup solenoid itself when the transmission warms up. Could very well be bad solder joints like OldBull suggested. May be repairable by you if you know how to solder well, but will need removal of transmission pan and then solenoid pack. Which is nothing compared to removing the entire transmission... six times in a row

 

[BBB]

Thanks i think its time to drain and have a look. I appreciate the input

 

[trackspeeder]

No converter lock up hot is a pressure issue. There might be an internal leak, low fluid, or a cracked filter can cause this. Good chance the Teflon seal is damaged causing a leak when hot.

 

[LCAM-01XA]

Will said low pressure show up at the test port on the side of the case? If it does then checking for that is way cleaner than dropping the pan and all that mess...

 

[OLDBULL8]

Rereading your 1st post. You say the fluid is good.

Check fluid level just before you take off, "start and warm truck few minutes head out on the road tcc locks up", if it's up to the MAX mark or over that on the dip stick, it's too full.

Check the fluid level after running your 5-6 miles and trans fluid is good and hot, "fine for 5 to 6 miles then when I stop at intersection and get back up to speed no lockup" , if the fluid is over the Max mark, the fluid is overfilled.

Over filling can cause the fluid to get aeriated, the pump doesn't like to pump air, the pump pressure can lower enough to cause your no lockup, the stator shaft Teflon seal from pump to TC might leak at that time causing a no lockup.

You could check the pump pressure at that time, but you would have to connect a gauge to the pressure port by the MLPS with a hose into the cab. Pressure at 35-40 MPH should be around 250 PSI.

trackspeeder might confirm this.

Always check the trans fluid level in Park or Neutral , engine running and hot.

 

[trackspeeder]

Will said low pressure show up at the test port on the side of the case? If it does then checking for that is way cleaner than dropping the pan and all that mess...

Its much cleaner than dropping the pan. Unless the pressure gauge hose starts leaking.

 

[BBB]

ok I have checked the resistance of the TOT it runs 12k with trans fluid cold 30 degrees f outside and sat for a day i warmed truck up drove around till it quit locking up converter and ohms are OL or open ??? oddly enough it does not lock up when I ground converter wire ?? two problems ? one causing both? I know their is a reason I wanted a manual but I cant seem to remember why ?? it would explain why it switches off like a switch was thrown I guess it wass any help greatly appreciated Im guessing solenoid pack but would like to be sure thanks

 

[trackspeeder]

The solenoid pack is shot.

 

[BBB]

Thats what I figured thanks for the response any sugestions on where to get new or is rebuilt ok?

 

[OLDBULL8]

Your gonna have to drop the pan and pull the pack. Maybe you can see the problem than (solder joint)? Ebay has them.

Installing the new pack, takes a #30 Torx bit and a 10mm socket. Tighten to 80-100 Inch lbs.

Snug up the nut on the stud first, then snug up all the bolts evenly then tighten in a criss cross manor, tighten stud nut last.

Slob some dielectric grease in the connector before installing.