Quick Question regarding OD band/Servo issue in 5R55W tranny

[dmenke]

I have narrowed down my transmission problem to either a bad OD servo, or a broken band. I am sure there is servo bore wear, as it has 135,000 miles. Last night on the way home from work, I lost OD in a stiff headwind. I was going highway speeds (65) and the tach was at 3000 instead of 2000. Hence OD out.

Further testing today has led me to believe I have no OD function, due to one of the two above malfunctions. I am leaning to a failed band, due to the relatively rapid onset of symptoms. Shifting has been firm, but consistent the entire time I have owned the vehicle. After all that, here is my question:

Is driving the vehicle going to do any further damage, or more likely to leave me stranded than an otherwise healthy 5R55W would? There is odd shifting due to no OD band function, but no slippage, and other than higher than normal cruising RPM, there does not appear to be any ill effects. It will be rebuilt eventually, and I will speak to the technician about the servo issues in the next month or two, but I cannot afford to not drive.

Thanks,

Doug

 

[BrooklynBay]

Do you have a check engine light or a flashing O/D light?

 

[dmenke]

Do you have a check engine light or a flashing O/D light?

Yes, the OD light is flashing.

 

[imp]

I have narrowed down my transmission problem to either a bad OD servo, or a broken band. I am sure there is servo bore wear, as it has 135,000 miles. Last night on the way home from work, I lost OD in a stiff headwind. I was going highway speeds (65) and the tach was at 3000 instead of 2000. Hence OD out.

Further testing today has led me to believe I have no OD function, due to one of the two above malfunctions. I am leaning to a failed band, due to the relatively rapid onset of symptoms. Shifting has been firm, but consistent the entire time I have owned the vehicle. After all that, here is my question:

Is driving the vehicle going to do any further damage, or more likely to leave me stranded than an otherwise healthy 5R55W would? There is odd shifting due to no OD band function, but no slippage, and other than higher than normal cruising RPM, there does not appear to be any ill effects. It will be rebuilt eventually, and I will speak to the technician about the servo issues in the next month or two, but I cannot afford to not drive.

Thanks,

Doug

@dmenke
Any OD OFF flashing light? If so, codes are present. If not, at 65 mph against strong headwinds, especially uphill, the first thing to "downshift" is the Torque Converter Clutch (TCC) unlocks. Still in 5th (OD) gear, 3000 rpm is easily possible as the Torque Converter comes into play. If still more power is demanded then the trans. will downshift from 5th. to 4th. gear, with the TCC still unlocked. The TCC will not re-engage again until 5th. gear is again attained.

Drive at low throttle, getting up to cruising speed, perhaps 60, holding it there. Depress O/D OFF button, observing tachometer. If rpms jump up several hundred, the trans was in 5th. gear. Depress button again, if rpms drop back down to previous level, your OD is apparently working. Use the tach to observe what your trans is doing. At constant cruise speed on level roadway SLIGHTLY increasing gas pedal pressure should show NO IMMEDIATE increase in rpms on tach; then, as vehicle speed slowly increases, the tach will slowly show eng speed increase. If tach IMMEDIATELY jumps up, your TCC is not operating properly.

Your description leans toward suspicion of the TCC rather than OD gear. Generally, trouble with either will flash O/D OFF, indicating trouble code present. Don't sell the OD system (band, servo) short. Mine has 156,000 miles on it, never serviced, still works fine. imp

 

[dmenke]

The OD button has no effect whatsoever. sluggish accelerating from a standstill leads me to believe it is starting in second, and OD light starts blinking almost immediately. If I cancel OD before moving, OD light will soon begin blinking, and still no OD in any driving conditions or wind direction.

 

[imp]

The OD button has no effect whatsoever. sluggish accelerating from a standstill leads me to believe it is starting in second, and OD light starts blinking almost immediately. If I cancel OD before moving, OD light will soon begin blinking, and still no OD in any driving conditions or wind direction.

@dmenke
I would say, then, that the TCC is not at fault. imp

 

[BrooklynBay]

Could you find out what the trouble codes are, then let us know?

 

[dmenke]

OK, finally got the codes:
P0745 Pressure Control Solenoid A
P0731 Gear 1 Incorrect Ratio
P0733 Gear 3 "
P0734 Gear 4 "
P1000 OBDII Monitor Testing Incomplete

Looking them up now. Kinda wondering about P0745...

Doug

 

[imp]

OK, finally got the codes:
P0745 Pressure Control Solenoid A
P0731 Gear 1 Incorrect Ratio
P0733 Gear 3 "
P0734 Gear 4 "
P1000 OBDII Monitor Testing Incomplete

Looking them up now. Kinda wondering about P0745...

Doug

@dmenke
Looks like it's telling you operating pressures are out of whack, due to inoperative or partially inoperative Pressure Solenoid. The transmission, if original in a 2004 is a 5R55S, not "W".

Incorrect operating pressure causes internal shafts to turn at speeds outside the predicted range, PCM (computer) picks up on that, displys "incorrect ratio" codes, meaning shaft speeds are wacko.

Good chance, IMO, replacing the Solenoid Module, which has all 8 of them in it, will solve the problem. Before saying "go", I'd feel safer hearing from JK080 first. Maybe PM him, he will know. imp

 

[BrooklynBay]

Did you check the internal wiring harness in the transmission, and the bulkhead connector?

 

[dmenke]

Did you check the internal wiring harness in the transmission, and the bulkhead connector?

Have not yet. I am helping a friend get his truck running, and then we will put it on the lift, and drop the pan, and check a number of things, including the wiring harness...

 

[SyberTiger]

If you suspect a broken OD band I believe you can fairly easily check it. Go through the band adjustment process and that'll tell you if your OD band is still there and intact. Look at THESE INSTRUCTIONS under the heading "Band Adjustment".

 

[BrooklynBay]

I have a band adjustment thread in number 4 in my list of useful threads: http://www.explorerforum.com/forums/showthread.php?t=158160.

 

[doug625]

What ended up being the problem?