Loosing 4th once converter is locked

[alian]

Hey guys. I have just installed a a rebuilt 4L65e and a 3k stall into my Crewman and on some hyway testing I have found the following. The converter locks in great at 85kph (53mph) but after about 5mins on the hyway it seems to unlock and go back to 3rd. Temps are all good 95c max,
No DTCs have been logged, but we can overide and command 4th with efi live.It is hard to work out wether the stall is unlockin 1st or we are loosing the signal and droping to 3rd which would unlock the converter as it happens at the same time. Once lost you can not get it back to 4th, tried playing with the shifter, adjusting speed of car, stopping and restarting car.
The funny thing is that while limping home we found 4th again(as in it just started working again) so about 5mins of 4th followed by aprox 5mins of 3rd and so on. We have talked to the box builder (well known) but is over a1000 km away and he says that it cant be the box.
So anybody out there got any ideas.
Cheers Ian

[Taz]

Post your tune when you get a chance … will take a look.

Was the original transmission also a 4L60/65/70 variant ? I take this problem just presented itself after the install of the “new” 4L65.

Any changes to the tune made concurrently with the installation of the transmission ?


Regards,
Taz

[alian]

Taz. Yep it was a 4l65e that came out aswell. I had never had this problem before the install. The only chages to the tune was lock up speeds and some pressure changes. I dont have a std tune to compare but I have the car booked into Holden on Friday to have the std tune installed. I will then save it my laptop and start again just incase I have a problem somewhere that I cant put my finger on. I will post tune as soon as I have worked out how to do it.
Ian

[alian]

File attached.

[Taz]

Hello Ian,

The attached tune should be considered for diagnostic purposes only - wondering if there may be an issue with the TFT sensor. I eliminated the “Hot mode” shift behaviour in the 3>4 and 4>3 PT portion of the TCM tune. Also adjusted the 4th gear TCC apply / release parameters - to also eliminate the “Hot mode”.

If this helps, then the issue is probably the TFT sensor.


Regards,
Taz

[alian]

Thanks mate, I get what you have done, great thinking. I was going to test it today but it is pissing down rain and have had to get over to the workshop to clean as we have a little cyclone that is supposed to hit late tonight. I will test tomorrow.
Cheers Ian

[alian]

By the way is there a pid for what state the auto is in??, NORMAL,PATTERN "A", "B" or HOT State .This would confirm that is going into hot state.
Cheers Ian

[alian]

Ok, did the testing, and it came back that with the new settings it didnt loose 4th at all. The TFTs are steady at 95C so what would be throwing the tranny into hot mode if the temps are ok. Or is there a setting that you can set where the hot setting cuts in. Has any one out there have any idea if there is a pid to monitor tranny mode. NORMAL,PATTERN "A", "B" or HOT State.
Cheers Ian

[Taz]

Glad to hear the “new” transmission shifts OK with the modified tune. You stated your temps were steady at 95C (203F).

Is that the engine coolant temp or the TFT (transmission fluid temperature) ? If 95C refers to coolant temp, that is normal. If that is the TFT - that seems too hot - generally don’t like to see this value over 75C. Not sure if TFT in the 95C range are common in your climate - still seems a little too hot.

I’m on the road for the day - no access to manuals or tuning software. Will try and check for PIDs and the threshold for “Hot mode” when I get home this evening.


Regards,
Taz

[alian]

Thanks. That is TFT . I have gone over all my logs from when I started 3 years ago and have always seen up arround 93degC tranny temp. I now have a stall converter fitted but have also fitted a tranny cooler to help.
Cheers Ian

[Taz]

Hello Ian,

The following should be taken as general information … bearing in mind my “so called” area of expertise is Gen III conversions - not Gen IV setups. The 4L65 you have is very similar to Gen III variants - with the exception of the addition of an ISS.

The below information is from GM service manuals of North American produced trucks (my primary source of parts and harnesses) - your Holden produced vehicle may vary.

The TFP (transmission fluid pressure) assembly bolts on the bottom (pan side) of the valve body (usually by 3 long and 2 short bolts). The TFT (transmission fluid temperature) sensor is incorporated into the TFP assembly. The TFT sensor is a “thermistor” - similar to the ECT (engine coolant temperature) sensor.

The TFT sensor has a range of 0 to 5 volts. When the TFT is cold the resistance in the sensor is high, and the voltage is also high. The reverse is also true.

5 volts = -40C (-40F)
0 volts = 151C (304F)

“Hot mode” is triggered at 135C (275F). There are many situations (and DTCs) that inhibit the torque convertor from locking in 4th gear. Generally, only “Hot mode” will inhibit 4th gear itself.

Many transmission DTCs do not illuminate the MIL in the IPC - a scan for any / all stored transmission DTCs would assist in further diagnosis of the problem.

My “instinct” given the diagnostic efforts thus far - is a defective TFP assembly, or a poor / intermittent connection to the TFT sensor - as “zero volts” (or no connection) from the TFT sensor will be interpreted as a “hot” transmission.

Regarding transmission PIDs that may assist in diagnosing the current problems …

Current gear = GM.GEAR (caption is GEAR)
Shift pattern = GM.TSHIFT (caption is TSHIFT)
TCC enable = GM.TCCS (caption is TCCS-TCCEC)
TCC control solenoid = GM.TCCS (caption is TCCS-TCCCSC)


Regards,
Taz

[alian]

Taz, Great information. I have a question though, if the TFT sensor is faulty and is the cause of the tranny going into "hot mode" you would think that the TFT readings while logging would have to spike up above where the readings are. Just trying to get my head arround it.
Cheers Ian

[Taz]

Hello Ian,

As I stated previously, a problem with the TFP / TFT system is only my “instinct” - just a possible option - the only thing you have changed is the transmission itself - the problem may turn out to be something else. Not sure if the transmission temperature PID is actual or calculated, or how an intermittent connection would affect the PID.

I’m basing my “hunch” on the elimination of the 4th gear “Hot mode”, and the subsequent “normal” shifts of the transmission. More diagnostic work is required to eliminate other options - difficult to be more precise from half way around the world.

I have done Gen III conversions for a while now, just getting into the Gen IV. On a couple of Gen IV conversions that I have helped out with, I have observed the transmission shift pattern (when logged) oscillate from Pattern 1 / Hot / Cruise - etc., for no reason known to me. On those vehicles, I set all the shift patterns to the same parameters to “stabilize” the shifts.

Not sure if this phenomena is occurring in your vehicle - until you try and log it. If it is, hopefully a Forum member with more Gen IV experience than I, could answer why this happens - I would certainly like to know.


Regards,
Taz

[alian]

"I have observed the transmission shift pattern (when logged) oscillate from Pattern 1 / Hot / Cruise - etc., for no reason known to me"


Taz were you using Shift pattern = GM.TSHIFT. I am off to Holden to get the original tune today so I can start afresh.
Thanks again for all your help.
Cheers Ian

[alian]

Update!! Holden were unable to overwrite the tune as I already had the latest calibration. So still on the lookout for a std tune for it.
CheersIan

[limited cv8r]

What OS number are you looking for? What year model crewman?

[limited cv8r]

Woops, just looked at your attached tune.I have a few here with the same OS. I have done a compare of them and they are all identical, so I have uploaded this one for you.

[killerbee]

I saw a similar thread on this. Very similar. TFT voltage scaling difference?

[killerbee]

http://www.gm-trucks.com/forums/index.php?showtopic=123115

[alian]

Woops, just looked at your attached tune.I have a few here with the same OS. I have done a compare of them and they are all identical, so I have uploaded this one for you.

Many Thanks mate. I have looked at your tune but it has been modified. Do you have the original? Or is the date that every thing was modified (Feb 15, 2007) the date that the standard tunes weas modified?
Cheers Ian

Killerbee, Interesting stuff

[alian]

Ok on the weekend I managed to some more testing and have found this.
Test 1.Pid TBASEPAT code changes from 11 to 9 in with hot state tuned out. No converter lock out during test
Test 2.Pid TBASEPAT code changed from 9 to 4 when at normal driving the converter unlocks for no apparrent reasonand dropped back to third.
Unfortunatley I didnt have TFT and VSS pids loaded.
Logged TCCE,TCCEP,TCCES,TCCEO. They all changed at the same time as the converter unlocked.
TCCE went from unknown to CMD off only fo 3.45secs and went back to unknown.
TCCES,TCCEP and TCCEO all went from unknown to failed back to unknown over the same 3.45 sec periord.
All mills were turned on but didnt throw any codes.
If anybody out there has any idea it would be great.
Cheers Ian

[Taz]

Hello Ian,

Glad you found PIDs that worked for you. Looks like the transmission shift pattern is “jumping around” - as I stated previously, I have observed this phenomena before - but I don’t know why it happens.

A couple of possible options come to mind …

As the previous transmission worked appropriately with your current ECM / TCM tunes, I would install the TFP assembly from the original transmission into the “built” transmission. This is straight forward - remove the transmission pan and you will be looking at the TFP assembly. This also has the side benefit of facilitating a transmission filter change (and partial oil change) while you have the pan off.

Alternatively, you could completely remove the “Hot mode” via programming. If you choose this option, the addition of a standalone TFT gauge may be prudent.

If your vehicle is equipped with any type of switch that alters the transmission shift pattern (like the Tow / Haul switch in trucks) then you will need to retain individually programmed shift patterns.

If your vehicle does not have a switch that alters the shift pattern, then all of the shift patterns could be programmed to the same values - which would stabilize the transmission behaviour.

Obviously, whatever approach you choose when programming the shift patterns, will also have to be consistently applied to the TCC apply / release patterns.


Regards,
Taz

[alian]

Thanks again Taz. I have to check wether the box is still here or has been sent back to the builder. I will be doing more testing in the next couple of days and will post results.
Cheers Ian

[alian]

I have a segment of log where the converter unlocksand drops to third as earlier explained. you can see where TBASEPAT switches from code 11 to code .
Cheers Ian

[joecar]

Can try logging TCCMODE and TSHIFT if available.

[joecar]

I have a segment of log where the converter unlocksand drops to third as earlier explained. you can see where TBASEPAT switches from code 11 to code .
Cheers IanAlso log TSTATE05, 09, 10.

[alian]

No Problem, Will give it a test. Will take a couple of days before being able to get out and test again but will let you know.
Cheers Ian

[alian]

Finaly got some time to do some testing. Joe I was able to get some of the pids you suggested to validate. l coudnt get TSTATE05, 09, 10 or TSHIFT to work. I got TCC mode to work and I need to work out what the description acualy mean as the TCC locks I get datta saying "lock" for a couple of secs then it goes to "slew" for the whole time until its does its usual trick and unlock for no apparent reason. I would assume that it should say locked. I am trying to confirm if its the box or the TCC that may be causiing the problem. The box builder has said he will build another box for me but if I fit another box with the same converter I am no better off. And like wise if I change the converter. If I replace the lot I will never no what it was. Lus the suppliers will want to know aswell.
Chees Ian

[joecar]

Slew is an intermediate state between unlocked and locked, the TCM is slightly slipping the TCC on purpose...

try setting the D6032 TCC Sol Max PWM to 100% and the D6031 TCC Sol Min PWM to 95%.

[alian]

Hey Joe is that for testing purposes or keep it there? D6032 lowest setting is 98 but D6031 setting are no higher than 34 max.
Cheers Ian

[joecar]

Set D6031 to 95%...

if that keeps the TCC locked (as far as you can tell via SOTP) then keep it there...

i.e. the TCM will still "slew" the TCC, but the slew range will be 95%-98% rather than 34%-98%...

Anything above 85%-90% usually locks the TCC (i.e. no slip).

[slow67]

Set D6031 to 95%...

if that keeps the TCC locked (as far as you can tell via SOTP) then keep it there...

i.e. the TCM will still "slew" the TCC, but the slew range will be 95%-98% rather than 34%-98%...

Anything above 85%-90% usually locks the TCC (i.e. no slip).

I usually set mine to 99%.

[alian]

Will do and see how that goes.
Cheers Ian

[alian]

Ok, Time for an update. I finaly got out to do some more testing. Set D6031 up to 97%, Made no difference at all, still went from lock for a milli second to slew and held that for 5 mins before unlocking and going back to third. We are going to try changing out the stall to a TCE over the next week or so and see how that goes. We are thinking that the stall is not allowing full lock up and after trying for the 5 min or so it lets go.
Cheers Ian

[Taz]

Hello Ian,

Quickly reviewed this entire thread … I had posted a diagnostic type tune with a disabled 4th gear Hot Mode - in post #5. In post #8 you posted a response, that while using this diagnostic tune the transmission “didn’t lose 4th at all”.

Did the convertor also remain locked during the test drive with this tune ? If so, then it is not the convertor preventing a lock (or failing to remain locked) - but the tune, TFT sensor, or other (yet undiscovered) factor.

Just wanted to clarify this point with you - don’t want to see you needlessly going through all of the effort (time, money, & inconvenience) of replacing the convertor - only to have the underlying problem remain.


Regards,
Taz

[alian]

Hey there Taz, I will go back over it and check again. I have done so many things now that my head is fried, And only have limited time to do things, hence the delays to test.
Thanks heaps Ian

[JezzaB]

UPDATE: New gearbox was put in and a new, tighter converter and its the same.

[joecar]

Are any of the bits on in the pids TSTATE09 and TSTATE10...?

[Taz]

I was concerned with that potential outcome .......


My condolences,
Taz

[alian]

Me to Taz. By changing the auto aswell it change the Trans temp sensor so now that is out of the picture now 2.
Ian

[Taz]

Perhaps ... but perhaps not ... depends if the trans temp sensor in use is compatible with your original TCM tune ... would have been helpful to have retained the original trans temp sensor for diagnostic purposes. This is generally not an issue, but given your situation the more variables you can eliminate, the better.


Regards,
Taz

[alian]

Joe state 9 and 10 dosnt work with my set up, I have tried to validate them without success.
Taz, There is not alot of T42/E38 combos in Aus. Unfortunatly My box went back to the builder(over 2000kms away ) and would have been built and be in someone elses car by now. So it could be something quirky but I am still looking. I suppose I could get onto Holden and see if theTrans temp sensor for my vehicle has the same part No as the rest of the T42 boxes. Worth a look. ( at least that would eliminate that) The TFT sensor is reading about right as it sits pretty close to the ECT all the time.
Cheers Ian