4R70w ..shifting issues....TC lockup?

[mnealuf]

I have recently purchased a 1997 F150 (2 wks) ...I know it is no Explorer but Glacier Brooken Bay and some others have been way beyond helpful in my issues with my other car...a 2000 Explorer. Anyhow it is 4x4 ext cab w/ 120k. It has the 4.6 and the 4R70w tranny and last weekend I degreased the motor and got the plug/wires wet and it ran like crap until I put new wires /plugs in it. Runs good again but tranny shifts really hard from 1-2 and 2-3 and shutters really bad and nearly stalls when you come to a stop , like the TC is not releasing. The truck always shifted a little hard from 1 to 2 but the person I bought it from said he had a performance tranny shop put a reman tranny in 6 months ago and thought maybe they put a shift kit in it. I took it too a local tranny shop to pull the codes (although the OD light was not flashing).
They put a Snap-On scanner on it and no codes. The guy drove it and said the TC is locking up WAY too early and not releasing..that is causing the shudder when truck rolls to a stop, shifts points are fine. I think his scan tool showed if TC was locked/unlocked. He also said the brake should unlock the TC automatically and it had no effect. I noticed if I manually downshift it into 1st as the truck gets to about 10 MPH no shudder as truck stops...might mean nothing..someone said that means the mechanical part of the TC lockup is working....might be a clue to those who know more than me. He recommended pulling pan and draining TC..which he did. Oil and pan looked totally clean..like operation table clean....almost too clean like someone just was just in there. (recall I just bought truck a little over a week ago) . Of course he said for a cool $1600 he will rebuild tranny and new (reman?) TC. I am hesitant because other than a slightly firm 1-2 shift I had no issues prior to this(although it was only a week of driving) I am now scared to drive it....if the TC is coming apart it will get ugly fast. I am out of town for work until the weekend and plan on messing with it over the weekend.....can I test the TC lockup solenoid externally with basic tools (ohm meter)?

 

[toy720]

Yes you can check the tc solenoid look at Glaciers 4r70w rebuild diary for reference Thats what I was thinking was that your solenoid might be going bad. I cant remember the specs on the sensor prob around 8-16 ohms(just a guess) but there probably cheap enough to replace. I would just replace it.

 

[Glacier991]

Also check your wiring harness and the case connector.

 

[mnealuf]

I had about and hour tonight to mess with it and I cleaned and checked the harness where it plugs into top of tranny on pass side, right above the pan......I think that is entrance to the VB stuff. Connection was clean and dry...no change. In the morning I will try to follow the harness up to the engine compartment and check those connections.. It is surprising difficult to follow the harness, nota lot of room back along firewall in this truck. I discovered if I start truck and shift into 2nd gear the truck stalls...I assume because the TC is locked up...does that mean anything to those in the know????

 

[mnealuf]

I re-cleaned the connector at the transmission and followed it up to main harness on pass. side firewall. Took the connector apart and removed the purple/yellow strip wire from the plug. I think that should have made the TC never lock up. I drove it and it acts the same...I put a multi meter on the computer side ad I get resistance (although higher then I would have expected) when I think it should tell the TC to lockup....high speeds steady throttle..and then throttle to idle /coast or brake on makes circuit go open. I believe that means computer is OK....I also noticed that if I start truck and put it in 2nd and not "D" or 1st the truck almost stalls., must be because the TC is not releasing. I measured the TCC wire going from firewall connector and it is "open" to ground.......I thought maybe it would be shorted. I also expected it to be whatever the resistance of the solenoid is..strange it is open.

UPDATE: I dropped the pan and removed and measured just the TCC. It measure 1.6 ohms. I also broke the connector clip that makes sure it stays attached...aaaahhh my week/day/weekend has been like this. I think I can use a very small wire tie to serve same function when I re-assemble. But I digress. I also read somewhere you can put +12V across it and it will click 9it is solenoid after all) ...which I did in both polarities...nothing. Maybe the TCC is dead and locked "open"?

I am sorta confused because the of the 2 types of TCC have different values for resistance , up to 1996 is 1-3 ohms and post 96 is 10-16 ohms. according to the year of the truck (1997) it should be the newer higher R value but it is quite a cowincidence it fails into the lower range. Maybe the wrong TCC? (recall the truck had transmission rebuilt by previous owner ~6 months ago). To future confuse me the rebuild checklist (http://www.mn12performance.com/mn12-techinfo/trans-tech/4r70w_rebuild.html ) listed the TCC with white connector body as the post 1996...and mine is white.

 

[mnealuf]

ttt....anyone?

 

[Glacier991]

I'd try replacing the solenoid. I can loan you one if you like. I can also loan you the trans tester which replaces the computer and extenal harness and allows you to rule out the harness and PCM.

A failed EPC can cause harsh shifts in the 4R70W and that and the TCC issues still sound electrical to me - as in grounded (shorted) wire somewhere.

 

[mnealuf]

Thanks Glacier. I have a TCC ordered and hopefully it will be there before the weekend (next time I am home, currently traveling for work so I mess with the transmission on weekends). If the TCC does not fix I might take you up on the tester loan-out. Maybe I should try to check the internal harness (under pan), I saw you posted on a thread in the past where the harness was bad. Does it unplug from the bulkhead connector where it exits the top of the tranny. I didn't think about the EPC..that is tougher to test w/ regular ohm meter right. It definitely has TC locked up whenever the 1st/reverse gear by-pass can't shut it off...if I start it and put truck in 2nd it stalls. I also ordered a ATSG manual in my quest for knowledge. (I have one for the 5R55E in my Explorer) and that is useful. I have a Haynes but that is not very good in drive train areas.

 

[97BlackX5.0]

Was your overdrive light blinking at all while driving this?

 

[mnealuf]

Nope, the OD light never flashed. I took it to a local tranny shop and they pulled the codes and as expected (since no OD light) there was none. My thoughts (I might be wrong though as I am an amature) is since the the TCC had some resistance the computer would not know what was happening on the back end.....? The only time the light flashed is when I took the connector apart at the firewall to remove the TCC lockup wire from the plug ...then it threw a code and light flashed.

 

[mnealuf]

Update: I replaced the TCC and it solved the issues. I guess it was locked "open" mechanically and allowing the TC to enter lock-up. Since it was "open" or "shorted" the computer thought it was OK so no codes. (I guess anyhow) Why it surfaced when I got plugs and wires wet and the truck ran poorly for a day.?????/ I did notice the slightly firm 1->2 shift the truck has had since I bought it is gone. Maybe the TCC was partly stuck open and then when truck ran poorly and I manually shifted it and let it rev under high load the line pressure forced it father open? Then again Maybe a cowinkydink...and totally not related. Who knows., just pleased it is fixed. I did add one of those thru bolted drain plugs too to the pan, so that should help my ATF bathes Now I want to change gear oil in front and back differentials and TC fluid . But not today, going to enjoy not being under the truck on a weekend day. Thanks a million to Glacier and everyone who offered advice/assistance and moral support. Once again you guys are beyond helpful.

 

[shawnwayne42]

I have been having same issue on my 1997 ford explorer 5.0 it has same 4r70w. and is doing same thing except I replaced solenoid and doing same thing. when I put it in second it shift the 2 seconds later you can feel it lock it feels like a double shift. I am about ready to rebuild the valve body or maybe 2 gear accumulator spring?