2005 V6 Explorer Burnt out Torque Converter Clutch TCC

[chezzrob]

This 2005 V6 explorer has only done 60000 K, and has burnt out the TCC 3 times. Apparently 2 times with the previous owner (unknown to me) and once with me.

On learning that this was the 3rd time, I paid for investigation trouble shooting by a reputable trans specialist, but came to a dead end.

The final info is that there is nothing wrong with the transmission, however the TCC solenoid is not being told to lock up. This is apparent when cruising at speed. When the trans shifts into 5th the engine revs should drop a 1000 RPM, but sometimes it only drops 500 RPM and the scan tool says that the TCC solenoid has not been told to lock. If you continue like this it will burn out the TC Clutch. This fault occurs if there is a slight power applied (eg cruise control) when the trans shifts from 4th to 5th. If you manually drive it and ease off the power as the trans shifts, it will lock up.

Anyone know what senses power (vaccuum) and is this problem common at all.
Any one know an experienced auto trans shop in the states that could give advice over the phone as I live in Australia and no one knows much about explorers here. Need a specialists on the peripheral sensors and computer inputs / outputs type guy.

Thanks in advance

 

[imp]

This 2005 V6 exploer has only done 60000 K, and has burnt out the TCC 3 times. Apparently 2 times with the previous owner (unknown to me) and once with me.

On learning that this was the 3rd time, I paid for investigation trouble shooting by a reptable trans specialist, but came to a dead end.

The final info is that there is nothing wrong with the transmission, however the TCC solenoid is not being told to lock up. This is apparent when cruising at speed. When the trans shifts into 5th the engine revs should drop a 1000 RPM, but sometimes it only drops 500 RPM and the scan tool says that the TCC solenoid has not been told to lock. If you continue like this it will burn out the TC Clutch. This fault occurs if there is a slight power applied (eg cruise control) when the trans shifts from 4th to 5th. If you manually drive it and ease off the power as the trans shifts, it will lock up.

Anyone know what senses power (vaccuum) and is this problem common at all.
Any one know an experienced auto trans shop in the states that could give advice over the phone as I live in Australia and no one knows much about explorers here. Need a specialists on the peripheral sensors and computer inputs / outputs type guy.

Thanks in advance

Assuming you have the 5R55S transmission, with the usual programming scheme I have seen (not guaranteed for overseas use, though), The torque converter clutch (TCC) will NOT be told to engage until the transmission has achieved 5th. (overdrive) gear. You can confirm this by use of the tachometer and gas pedal; Do this with minimum throttle to achieve final speed of around 50 mph. Watch tach, first "bump", drop in rpm, signals 2nd. gear achieved. 2nd bump, 3rd gear, and so on, 4th bump is 5th gear. At that point, a SLIGHT increase in gas pedal will show rpm increase, keep pedal constant, speed constant, 45-50, another bump will present- that's the TCC locking up. At that point, SLIGHT gas pedal increase WILL NOT show rpm increase. What we're saying here is, use the tach. to determine if TCC is engaged; if it is, rpm "crawls" upward only slowly, as vehicle speed slowly increases. If the pedal is depressed TOO MUCH, the TCC will UNLOCK, and rpm will jump up by several hundred.

When mine achieves 5th gear, rpm drops much less than 1000, perhaps 3 or 4 hundred only, but bear in mind that drop depends on amount of throttle. Engine speed depends on the amount of "slip" in the converter; when TCC is engaged, that "slip" is zero, just like a mechanical clutch with manual trans. imp

 

[chezzrob]

IMP's message

Thanks. IMP. what you said is all good and agreed, the problem is that the solenoid is not being told to lock. The 1000 RPM difference between 4th and 5th is at 100 -110kph (68mph) which is our highway speed in Australia.

I am looking for feedback on sensors. It appears the trans is changing to 5th, but not locking. Need to know what criteria is required by the computer to send a lock signal to the solenoid.

in your comment "the pedal pressed to much unlocks the TCC" i would like to know what senses this. It could be a vacuum sensor or whatever. i can accelerate slowly when it does lock up, but it will not lock up if the cruise control is on. By nature cruise control are like a bit heavier foot type driving as they try to maintain speed. Am interested what senses this area of the strtegy. yes the trans is the 5R55S

 

[imp]

Thanks. IMP. what you said is all good and agreed, the problem is that the solenoid is not being told to lock. The 1000 RPM difference between 4th and 5th is at 100 -110kph (68mph) which is our highway speed in Australia.

I am looking for feedback on sensors. It appears the trans is changing to 5th, but not locking. Need to know what criteria is required by the computer to send a lock signal to the solenoid.

in your comment "the pedal pressed to much unlocks the TCC" i would like to know what senses this. It could be a vacuum sensor or whatever. i can accelerate slowly when it does lock up, but it will not lock up if the cruise control is on. By nature cruise control are like a bit heavier foot type driving as they try to maintain speed. Am interested what senses this area of the strtegy. yes the trans is the 5R55S

Vacuum is not used in any way. As a guess, the "criteria" used by computer to decide when to engage TCC (lock-up) is based on pre-programmed limits on data from sensors: vehicle speed high enough; 5th. gear engaged, eng. rpms within acceptable range, little or no "acceleration demand", AND, I missed this earlier, TRANSMISSION MUST ACHIEVE A CERTAIN MINIMUM FLUID TEMPERATURE before TCC lockup allowed. Mine sometimes goes several miles at 50 mph. about 2000 rpm, before it finally locks TCC, dropping to about 1400.

A lot of guys here, myself included, disagree with Ford's TCC strategy, and install a manual switch somewhere convenient about the steering column, and closed it to engage the TCC during most forward driving over perhaps 30 mph. Forget to open the switch upon coming to a stop, kills the engine. Such a temporary switch could confirm/deny whether your TCC is acting properly upon demand. If it IS confirmed normal reaction to application of voltage to the TCC solenoid, then either the computer is faulty, or an intermittent bad connection exists in the harness somewhere between PCM and solenoid connection at transmission case.

One could confirm/deny proper PCM apply of voltage to the TCC solenoid by connecting a voltmeter between the solenoid connection (preferably at the transmission case, where the leads enter the box) and ground, then drive the vehicle, remember fluid must be up to temperature, and observe whether PCM applies 12V. to the solenoid at the expected time, and MAINTAINS it until it should be turned off, such as sudden gas pedal demand, complete RELEASE of gas pedal (yes, they DISENGAGE the TCC everytime one lets OFF the gas pedal! (?), gradual slowing of vehicle with gas pedal still in demand should keep TCC engaged until drop down to about 40mph.

Do you guys use KM/hr? Christ, no wonder I'm being confusing! Keep at this, I'll help if I can. imp

 

[chezzrob]

pcm OR ccm ?

Thanks IMP, much obliged.
Have alook at Sparkys post
http://www.explorerforum.com/forums/showthread.php?t=148433

scroll down to CCM.
Sparky says that the CCM outputs to the TCC solenid. He also has posted about the PCM if you scroll further down.

Is this CCM part of the PCM or are they seperate computers ?

Funny about the switch, its just what my mechanic said to do..
however the car has only done less than 40 000 milels and if I can fix this I want to keep it. Should get 200 000 miles out of it.

If you look at Sparky's post CCM inputs, can you identify a likely faulty sensor that would narrow the sensitivity of power being applied. If i could widen that range then it would lock up more readily. The problem seems to be power related. also how does the CCM know its in 5th gear?
The trans specialist suggested if a speed sensor was faulty i would have a whole lot more trouble than this, so he assumes the speed sensor is ok.

 

[imp]

Thanks IMP, much obliged.
Have alook at Sparkys post
http://www.explorerforum.com/forums/showthread.php?t=148433

scroll down to CCM.
Sparky says that the CCM outputs to the TCC solenid. He also has posted about the PCM if you scroll further down.

Is this CCM part of the PCM or are they seperate computers ?
Funny about the switch, its just what my mechanic said to do..
however the car has only done less than 40 000 milels and if I can fix this I want to keep it. Should get 200 000 miles out of it.

If you look at Sparky's post CCM inputs, can you identify a likely faulty sensor that would narrow the sensitivity of power being applied. If i could widen that range then it would lock up more readily. The problem seems to be power related. also how does the CCM know its in 5th gear?
The trans specialist suggested if a speed sensor was faulty i would have a whole lot more trouble than this, so he assumes the speed sensor is ok.

OK, I looked at the link, saw "BCM" mentioned, but not "CCM". I suspect the "issue" is building upon itself; this cannot be as complicated a problem as it appears. Below is the complete 5R55S wiring schematic. If you yourself are not experienced adequately to follow and understand such wiring, look it over very carefully to become acquainted with all the terms and items, then ask your mechanic guy to review it. Forgive me for being so simpleton, but not knowing where you stand, makes it useless to present things not familiar to you.

The "turn on" output to the TCC solenoid originates at PCM pin #5 . The other TCC sol. connection is in common with ALL the solenoids, and provides the 12 volts needed for their operation. Tracing back up from the bottom (common) TCC terminal, we see it receives it's power from a fuse, looks like [URL=http://www.explorerforum.com/forums/usertag.php?do=list&action=hash&hash=3]#3 7[/URL] , 15 amp. rating. Aside: That fuse is only "on" or operative, or "hot" if you will, when the PCM Power Relay is energized; this happens when the ignition key is turned to "on" or "start". The moving contact arm in the Power Relay is "hot" at ALL TIMES, receiving power from a large main fuse, F-11, 40 amps., these fuses being found in the Battery Junction Box (dotted outline) underhood.

Now, as you can see, there are 3 speed sensors. The "turn-on" signal to TCC will not occur until the PCM "sees" a pre-programmed minimum fluid temperature in the transmission. This is done via the "TFT" (Transmission Fluid Temperature) sensor shown within the solenoid module. TFT "enables" all three speed sensors to provide data to the PCM. Each speed sensor's output to PCM may be acted upon by PCM independently of the other two. Unimportant fact to this discussion.

At this point, I must go back and re-read your original post(s), to determine whether TCC seems to be working intermittently, or not at all. Here is what I would do, if it were mine: Open insulation of correct wire in harness AT the transmission which feeds the TCC solenoid: #14 in the connector there (shown violet/yellow, but can't count on color correctness), solder one wire of a length of twisted-pair wire like lamp-cord to the bared spot, make sure it can touch nothing else conductive or tape it, connect other wire to a good ground location, on the FRAME, scratched shiny-clean for good contact. Run the pair of wires up into the cab, drive until certain transmission is hot, perhaps 15 minutes or more, depending on ambient temp., have a good D.C. Digital Voltmeter connected in the cab, I use a Simpson Multimeter Analog type, watch the signs: when tachometer shows 5th. gear achieved, under least throttle necessary to maintain speed ~ 50mph, meter should indicate about 12 volts IF PCM has commanded TCC lock-up. Doing this AT TRANS. eliminates possibility of an "open circuit" in that one wire feeding the solenoid somewhere between the PCM and Trans., OR! The PCM is NOT commanding TCC lockup. That case COULD be caused by faulty speed sensor(s), OR faulty TFT, but I KNOW PCM can detect failure of either speed controls or TFT, based on current levels it expects to see there, as there are DTC's listed for TFT failure and speed control (all 3) failure.

NOTE that at trans. electrical connector, both #3 and #14 are shown as violet/yellow; an ohmmeter placed across these two terminals should read the D.C. resistance of the TCC solenoid coil: 9 to 16 Ohms. This must be done with ignition key in OFF position! Use a high-range setting at same time to measure resistance between either #3 or #14, and a good ground location; this indication should be very high, millions of ohms, if low, say less than 1000 ohms, a partial short to ground is being seen; that could occur most likely within the solenoid coil itself.

Challenging, and daunting, is it not? I'll get back later. imp

 

[chezzrob]

Excellent info Imp, thanks a lot.
I will be getting my head into this soon when I can get some spare time, however would like to know a bit about the temp sensor, and perhaps away to fudge it. Like put a resistor or something in the circuit. Any info about measuring the temp sensor welcome.

 

[imp]

Excellent info Imp, thanks a lot.
I will be getting my head into this soon when I can get some spare time, however would like to know a bit about the temp sensor, and perhaps away to fudge it. Like put a resistor or something in the circuit. Any info about measuring the temp sensor welcome.

Unfortunately, the fluid temperature sensor is not a simple "on/off" switch, but rather provides a variable resistance dependent upon temperature, the range of which voltage output causes PCM (through it's programming), to control variables OTHER than just "yes/no" of solenoid enable.

Look at the TRS, Transmission Range Switch, or DTR, Digital Transmission Range Sensor, on the right: This switch provides multiple inputs to PCM to tell it the position of the gearshift lever vs. other variables pertinent: speed sensors outputs, 4WD Control Module, position allowing "start", and back-up lamps on/off. I THINK, but am only surmising that, the programmers used TFT to give PCM a range of temperature values to work from, given a number of different driving conditions, such as considering extremes of ambient temperature to allow normal operation over-ride given certain circumstances, maybe like wide-open throttle, for example. I THINK.

If it helps you any, the TFT is likely a thermistor, here's it's operating characteristics:
0`F-31`F, 284K ohms to 100K ohms
32`-68`, 100K to 37K
69`-104`, 37K to 16K
105`-158`, 16K to 5K
159`-194`, 5K to 2.7K
195`-230`, 2.7K to 1.5K
231`-266`, 1.5K to 0.8K
267`-302`, 0.8K to 0.54K

This means at well below freezing temp. of water, it has very high resistance, allowing almost no current flow at all (284K ohms), but at the high temp. end of scale, it's resistance is around 500 ohms at 300`F. It is not clear to me whether PCM allows speed sensor inputs to be "accepted" at some discrete TFT output level, or whether it "accepts" 1, or 2, or all 3 individually, based on the TFT input.

In a nutball, you would have no idea what inserting a simple on/off switch might do to confound this messy technical gem of today.

We're getting too deeply into the nitty-gritty of operation here with inadequate knowledge of the how and why happens, based on Ford's programming of it all. Wish I could help you more. imp

 

[chezzrob]

Very Interesting. I think I will run a wire up to the dash and install a 0 -100k pot. At 0 the sensor will be as is, if I wind the pot up the PCM will think the oil is cooler than what it is. A post a reply on what I have found. Allow me a couple of months.
Thanks Imp.

 

[imp]

Very Interesting. I think I will run a wire up to the dash and install a 0 -100k pot. At 0 the sensor will be as is, if I wind the pot up the PCM will think the oil is cooler than what it is. A post a reply on what I have found. Allow me a couple of months.
Thanks Imp.

Will definitely like to hear the results! Admire your "pluck", sounds like something I would have done when I was much younger! Too hard to get down under those vehicles now! imp

 

[chezzrob]

Just wrapping this post up. I have been to busy to do any of the testing mentioned above but I have solved the problem, although it may be temporary, time will tell. The history of the explorer is unknown but it had HF radio antennas and Anderson plug which tells me it has done a lot of towing in its first 40,000k. Enough to stuff the Trans and consequently the torque converter. The torque converter has been replaced then the trans showed problems with locking the torque converter. By chance I came across a Transmission oil additive that one of its features is to dissolve varnish. I added that and the trans has shown no more faults. The Torque converter is locking up as it should, even under a slight power load. All fixed. I assume the varnish has accurred from overheating the oil, and has caused sticky valve movement. The oil has been changed out but this did not fix the problem until the additive was added. The additive I used is no longer available so if you in a similar situation you will have to go looking. The feature you are after is dissolve varnish.