P0741 no other symptoms

[heli58]

Hey all, I hope someone can enlighten me on a issue I'm having. I'm new to the Transmission work world, but have a pretty good idea of how it all works... This one has me scratching my head, though and I need a quick resolution since I need the truck to move across the country.

I have a 99 XLT with 183k on the original transmission. I'm the original owner and have serviced it regularly.

I have the infamous "O/D off" light blinking, but unlike every other thread here, I have no other symptoms that I can detect. The computer posts a P0741 code, indicating slippage between the input and output or TCC not locked. It runs fine, accelerates well, shifts smoothly and all is well. However, at some point down the road (can't pinpoint when or what conditions cause it (temp or speed or power requirements, etc), the OD light will start blinking. Sometimes it will be 10 miles down the road, sometimes 300 miles down.

When it's blinking, if I deactivate the OD via the pushbutton on the shift lever, the OD will disengage, as expected, but when I reactivate it, it will shift back to OD, but apparently not lock up the TCC completely because it stays about 200 rpm higher than the previous condition (expected because of the code being set). If I turn off/on the engine, it will reset and again go all the way to O/D again, but start blinking again at some random point down the road.

All of the shops want to rebuild or replace the transmission ("especially with that kind of mileage on it"). I'm not so sure. I've had other vehicles last me way longer without a $1800-2800 rebuild.

I know something needs to be done, but can't decide where to start. TCC solenoid? Flush? (the fluid is clean, correct level and not burned), EPC solenoid, TC?

I did a Stall test on the TC and it stalls around 2600rpm. Also, the TPC checks ok on the OHMmeter and Voltmeter.

Any advice would be appreciated... I need a quick resolution as I have to move from CA to NC at the end of Jan and I need it to pull a trailer (with which I won't be using O/D anyway...)

 

[toprankboxers]

You have described my issues to a tee...except mine had 154K, but mine shows a harder shift when slowing down but at the light or stop sign i shut it off and start it back up and it goes off and shifts fine....the trans shop told me yesterday...600 to 2500 to fix!!!! He said it was the torque convertor but could be more so just changing the convertor...please let me know what you find out..thanks

 

[heli58]

update

I did an engine flush yesterday. Does anyone know where three iddy biddy 1/16" (approx) diameter aluminum discs might have come from that I found in my tansmission pan? I assume they were aluminum, as they didn't stick to a magnet. They were less than 1mm thick. Additionally, there was quite a bit of sludge in the bottom of the pan...made about a 1" glob when all combined.

I still have the OD light blinking. I did notice, however, that the TC clutch does actually appear to disengage slightly before the O/D light starts to blink. I also noticed that if I drive with O/D off, the blinking never occurs, but I still see the TC lockup.

Can anyone give advice on where to go from here?

Thanks...

 

[manaen]

they are put in there at the factory and can be thrown away, although at this point I don't recall why they are put there :scratch: But I had the same thing when I installed my shift kit and new EPC. That just means that your pan has never been removed, or the person who removed it before did not clean the pan.

On the p0741 did you try to adjust your bands? and check your line pressure and EPC pressure. If your seeing an RPM differential then that probably rules out a problem with the ODS and OSS sensors in the tranny. Which points to more of a mechanical problem.

But I will defer to the more knowledgeable guys (and gals?) who know more then I do about these trannies.

 

[heli58]

Update to the update

Thanks for the info. I did another search of the forum and found http://www.explorerforum.com/forums//showthread.php?t=155213 which shows the "pucks" come from the OEM gasket. They're spacers to keep the gasket from getting too crushed in tightening. So, I'm not worried about them, they probably fell in during the removal process of the pan.

Anyway, yes I did adjust the bands. They were maybe a quarter turn off of where they started using the procedure outlined in the band adjustment thread.

Is there a user friendly way to check the line pressures vs EPC pressures? I found the pressure check thread [ http://www.explorerforum.com/forums/showthread.php?t=117998&highlight=pressure+transmission ] but that only shows the overall pressure, not the EPC (or am I missing something). Anyway, I'm in debate on whether to buy a TCC solenoid, TC or just plunk down the money to rebuild it.

 

[manaen]

I would check the pressures first, it could be as simple as your EPC being tired.

There are two separate ports one for checking line pressure (behind the DTR sensor on the driver side), and one for checking EPC (passenger side)

EPC should be 25 - 35 psi in D @ idle and 112 - 134psi @ WOT Stall

Line should be 80 - 110 psi in D @ idle and 228 - 263 @ WOT Stall

it is not recommended to hold WOT stall for a long time, just long enough to get your readings

 

[heli58]

Tran Pressures

Where'd you get those pressure numbers from? I have a service manual for from ATSG and it doesn't list the pressures (kinda bummed me that their troubleshooting don't really give troubleshooting help...just what the codes mean...I already knew that).

Do you have the values for normal driving operations (like when the OD shift/tc lock should occur?

Thanks again...

 

[manaen]

That's funny I got them from my ATSG tech manual (# 56400S) for the 5r55e.

Under normal driving conditions the pressures would be between the previously listed sets of values.

 

[heli58]

Pressures checked

Picked up a Pressure gage today. Here's what I got:

IDLE WOT
P/N 20 EPC / 95 Line
R 55 EPC / 80 Line 115 EPC / 320 Line
D 39 EPC / 60 Line 105 EPC / 225 Line
2 35 EPC / 57 Line 115 EPC / 235 Line
1 35 EPC / 55 Line 120 EPC / 235 Line

The D EPC pressure drops to around 20-25 during normal driving.

The Idle Line pressures do go up initially to the low end of the spec range when shifted, but drops down within a couple seconds of the shift.

So, what I see is low line pressures leading to slightly low EPCs? Or did I get a bad guage...?

Now where do I go with this? I didn't expect pressure problems since all the shifting goes fine and the TCC lock fail seems to occur with no consistency. I figured a TCC solenoid and EPC solenoid was going to be it based on everything I'd seen. Now I'm not so sure. Maybe the rebuild is in order?

Anyone got advice? Please chime in. I'm a week out from having to go the rebuild route before my cross country trip...

 

[manaen]

This should help

Update....
hmm the attachment quality really got degraded, here are some links direct from my webserver

Page1
Page2
Page3

 

[manaen]

There are a couple important notes on running the test on those pages..

 

[heli58]

Pressures are normal

Bump

I got some skinny on the definition of "idle" The pressure should be read around 1000-1200 rpm, not the 6-800rpm of foot off the gas idle. So, my pressures are ok now. The ATSG tech told me it can only be 4 things causing my problem and low pressure isn't one of them. TCC solenoid, VB, Torque Converter or Stator.

Back to the original problem. If you were me, what to throw good money at first? Solenoid? TC? VB or stator. Can you replace the stator? I thought it was part of the TC...

Thanks,
Heli

 

[manaen]

You can test the solenoids with an ohm meter although a bad solenoid will not always show bad resistance. have you read through the stickies in the tranny section? there is a few great writups on the 5r55e.

 

[heli58]

TCC solenoid - No Fix

I got a new TCC solenoid this afternoon and installed it. The old one tested good with the Ohmeter, matching the new one's resistance exactly. However, I was an optimist because the old one's valve body was loose in the mounting housing and the connector end had quite a bit of play between it and the solenoid valve assembly.

The solenoid bore was clean, no debris to be seen. So, I went ahead with the swap, and what do you know, it drove great for about 35 miles and then it started again.

I'm thinking the TC clutch itself now. Maybe just at the "first stages" of slipping which is why the computer takes so long to give up and at random times. The strange thing is, I'd think it would give up on uphill runs where there'd be more demand on it...but I see not such patterns.

I guess the VB could be and issue as well if there's a gasket about to go somewhere in there.

 

[manaen]

have you tried any of the Ford upgrades or the transgo shift kit? Also if your tcc was loose, do you have the upgraded solenoid bracket.

 

[heli58]

Narrow the cause

I haven't put in any upgrades yet. I'm just going through the possibilities. I hate just throwing parts downstream hoping to hit the issue, yet that's what seems to be the troubleshooting method everyone uses. Of course, the Tranny shops (and others, too) just say to rebuild it if it's starting to show problems at it's mileage. I dunno...

The TC solenoid was loose in its own bracket, not the long band that holds all the solenoids in place. the play I referred to is if you hold it by the connector end and valve end, you could twist it with about 2 degrees of play and wobble it slightly.

Is there a way to find out if it's the TC or if it's the valvebody without pulling them? I guess that's why they say, if you have to pull it anyway, you should just rebuild it.

Is there any way to find the real cause of this problem without the shotgun blast or random parts toss?

thanks.

 

[manaen]

one of the ford upgrades is a new bracket design, although I had some luck with heat treating mine and it worked great. The OEM brackets were very thin and very soft. Did you read through the 5r55e rebuilt diary in the sticky section of the tranny forum? It is a great read.

I don't like throwing parts at problems either, I would always rather diagnose them. The upgrades I am referring to is to address some weaknesses with the valve body. Many times during the removal of the valve body you will find the real problem and as part of the upgrades it will be fixed. The 5r55e VB gasket is a weak spot and ford addressed that as well by releasing a new separator plate that has bonded gaskets.

I don't believe in the let's just rebuild it attitude, there are times to do a rebuild, however too many times tranny shops just do a rebuild when it is not needed.

pulling the valve body down and checking everything is not a tough job, it can be done in an afternoon. If your TCC is loose in the bore then I would suspect that the holding clamp is bent. (mine was when I first did the upgrades about a year ago).

There are many cases of this code never being solved and people just chalking it up to a bad computer code. I find that hard to believe that it is just a "bad" computer code.