735 Failed Transmission Fill Calibration

[Chrisso]

Early 735, AWR008** s/n

Customer replaced modulation solenoids and called me to carry out fill calibration. Previous history, had a trans filter come apart and contaminate the system, then about the same time one morning machine lost all drive in all gears. Worth noting since replacing oil, filter and all modulation solenoids, we now have drive again. Customer reports trans oil pan being clean, suction screen clean also.

I attempt calibration, calibration aborted due to trans oil temp too high. Replaced trans temp sensor, same again.

Did some digging, to meet calibration start conditions the oil needs to be between 154 and 174 deg F. Sis states calibration automatically aborts once trans temp hits 180 deg F.

Can't understand why there's such a narrow temperature range for trans fill calibrations on these machines. Anyone else had this issue?

 

[Nige]

Can't understand why there's such a narrow temperature range for trans fill calibrations on these machines.

Seems crazy on the face of it.
Have you tried dumping the trans temp sensor in a bucket of hot water.? That should effectively fool the ECM.

 

[Mobiltech]

Yes I have had the problem and also cursed the software limitation on temp. It was years ago but I think I started on the low side and managed to get it done.
Did you check for a possible software update?

 

[Nige]

It was years ago but I think I started on the low side and managed to get it done.

I've seen that before on loaders. Despite the fact that the message on the ET screen gives a minimum temperature for the oil before a calibration will commence you can often find it will start at a lower temp if you slowly bring the temp up from cool and keep trying to start the calibration.

 

[Chrisso]

Did you check for a possible software update?

Sure did, put the latest software in it. Parameters didn’t change.

Im thinking I’ll have another go starting from the lowest temp possible. Failing that I’ll try the bucket of hot water as you suggested Nige.

 

[Nige]

Im thinking I’ll have another go starting from the lowest temp possible.

I've had good luck with that in the past. Start with the trans temp well below the lower limit and just keep pushing the "calibrate" button until it starts the process. You might get lucky and the process will start below the temperature it's supposed to.

The other option of course is to hook up a PWM generator to the transmission oil temperature sensor connector and use it to dial in a signal to the powertrain ECM that is bang in the middle of the range you want. Happy daze..........

As a side note, about how long was the calibration running before it fell over with the "temp too high" message.?

 

[Chrisso]

about how long was the calibration running before it fell over with the "temp too high" message.?

2nd clutch into the calibration. I let it go about mid way into the temp range before I started the cal, simply because I’ve battled to keep temperature in the transmission on other machines. Not this one it seems . Will try again as you suggested tomorrow.

 

[Birken Vogt]

Is the trans oil temp sender a 3 wire resistor with the signal somewhere between a 5v reference and ground, or similar? Maybe a pair of fixed resistors temporarily installed so that the module thinks it is 164 degrees the whole time?

 

[Nige]

Is the trans oil temp sender a 3 wire resistor with the signal somewhere between a 5v reference and ground, or similar? Maybe a pair of fixed resistors temporarily installed so that the module thinks it is 164 degrees the whole time?

It’s a PWM unfortunately.

 

[Nige]

2nd clutch into the calibration. I let it go about mid way into the temp range before I started the cal, simply because I’ve battled to keep temperature in the transmission on other machines. Not this one it seems . Will try again as you suggested tomorrow.

I wonder if, with everything that has gone on in the past as described in your OP, that there is something amiss with that clutch.?

 

[Chrisso]

I wonder if, with everything that has gone on in the past as described in your OP, that there is something amiss with that clutch.?

Well, I reckon you're right

Sure did, put the latest software in it. Parameters didn’t change.

And I was wrong, I mustn't have cycled the battery isolator for long enough. The new software meant the 180 deg F abort was no longer applicable.

So, i returned the next day and repeated the fill calibration, this time it failed on the last clutch in the process (clutch # 6, 1, 2, 3, 4, 5)...


This time the transmission got warm. From what I understand the 0009 error code can be caused by two things:
1) unstable TC and/or trans output speed sensor signals (which seem fine),
2) too many iterations (40+) calibrating a particular clutch... which makes me highly suspect slipping clutches and would explain the high temps during calibration.

So customer being customer they sent it ... truck made two passes before losing all drive and reported "a lot of smoke".

My thoughts, the reason the filter came apart was due to excessive moisture/water in the transmission oil. Since they don't use SOS and changed the oil before I got there we'll never know. That water I'm also guessing has destroyed multiple clutch discs.

 

[Nige]

That water I'm also guessing has destroyed multiple clutch discs.

If there are cellulose-faced clutch plates anywhere in that transmission it's highly likely.
Refer to Reusability Guidelines SEBF8115, 8031, & 8098 for more info............

 

[Chrisso]

Turns out clutch #1 was toast. Piston, discs & plates melted. System cleanout, transmission rebuilt, calibration passed and back to work.

 

[Nige]

Difficult to do diagnostics when the customer won't do the necessary (as in SOS, filter cuts, etc) and/or co-operate.

 

[Chrisso]

And the decision to run the machine one last time after the failed cal only added about 20% more to the repair bill, which I thought was good!

 

[Nige]

And the decision to run the machine one last time after the failed cal only added about 20% more to the repair bill, which I thought was good!

Ho f**king yas........
But customers such as that will never learn which is why there's always work. You only have to look at the thread posted by @Vetech63 - it's now up to 136 pages....!!

 

[Chrisso]

I'm scared I'll get stuck reading all 136 of them.

 

[nicky 68a]

 

[Nige]

Is the trans oil temp sender a 3 wire resistor with the signal somewhere between a 5v reference and ground, or similar?

Unfortunately not. The output of the sensor is a PWM signal.