transmission help

The flashing OD light is a sign that something is wrong.... left unattended, transmission problems have a way of snowballing.... At the time that the light is flashing, the transmission goes into what might be considered a "fail safe" mode. Line pressure maxes out in an attempt to keep clutches from slipping (hence the harsh shift feel) and the PCM (bless it's niave little heart) firmly believes that the owner is going to say "Uh-oh... better get that checked".

Without knowing which trans it is, total miles on the car, how many miles has it been driven "hurtin'"... codes... maybe some pessure and "what gears do I have" kinds of testing.. it's a crap shoot to come up with an answer that really means anything.. Is the concern very, very intermittent - or does it happen very regularly? So many questions, I know... but a good diag needs to have them asked and answered.

Occasionally, we see these kinds of things as an electrical concern... more often than not, they are mechanical or hydraulic problems. If it is an internal problem, the condition of the rest of the trans needs to be considered... If it's getting long in the tooth, the wise choice might be a rebuilt.... If the trans has a lot of miles, going in and fixing only the obvious problem could leave an owner with a ticking time bomb on his hands.

FWIW.... on both the 5R55 and the 4R70, I'd have to say that I see more direct clutch failures than anything else.

A good trans tech will start with fluid level and condition... a code scan... and (hopefully the trans will be acting up for this part) a road test - he'll be checking what lever positions work as they should.... whether there is engine braking when it should happen... upshift and downshift points. This part can be tough to describe... I don't know what I'm looking for.... but when I find it, I'll know.... Pressure testing can be very important as well.... Using this info, the appropriate band/clutch apply charts... a savvy trans guy should be able to nail the cause of the failure 90% of the time.

Not the answer you're looking for, I know... but the automatic trans is a pretty complex beast...

FWIW, the only "rebuild" kits that I know of come only with the fiber and steel plates and all the "soft" parts (seals, gaskets sealing rings...) and might not contain what it is you actually need..

Afterthought... I've heard of worn servo bores in the 5R55 giving grief... Haven't come across one myself, but there are aftermarket kits available to repair this condition.

Jim -

Not meaning to hijack this thread, but I have a related question. I own a 2002 Explorer V-8 with 5R55W transmission and 135K miles. Last year, on two separate occasions, the "OD OFF" light (the orange one on the right of the instrument panel) began to flash very rapidly. Both times, this occurred after pulling a lightweight (3500 pounds) camper trailer on level roads at turnpike speeds for more than two hours with the OD OFF switch activated, and it started not during towing, but as I slowed down at an exit ramp. After a few minutes of slow-speed driving, the light went off. Other than the fluttering light, nothing else seemed to be amiss.

A couple weeks later I took the vehicle to a Ford dealer, and they told me that an error code had indeed been set. They didn't tell me the code number, but said that the name of the code was something like "Improper second gear ratio". I don't think he did anything about it, and it never happened again.

My questions are 1) I can't find any reference anywhere to transmission-generated codes (as opposed to engine or emissions system codes). Can you point me to a list of these codes? I'm not nearly a good enough mechanic to screw with my transmission, but I am a curious type. And 2) what would/could an "improper second gear ratio" refer to, and why would it show up only after extended towing in 4th gear?

Many thanks for any answers you care to offer.

Bill Jeffrey

Bill... unlike OBD2 codes, transmission codes are "proprietary"... They can't normally be accessed with low end code readers and scan tools and it will be the manufacturer that decides on what a particular code definition is. IIRC, your Ex is fitted with the trans that has no dipstick.. fluid level is where the tech would have (or should have) gone after retrieving codes. While this might not offer any clues, it still needs to be done to rule out some basic issues. Unfortunately, the only real way to check fluid condition is to remove the pan.

Gear ratio error codes are most often the result of intenal transmission concerns... this next bit is more opinion than diagnosis... The OD band is applied in second gear as well as fifth gear. Your had OD cancel applied while you were towing so there would be no indication of any 5th gear concerns. Your light came on only while you were towing... this indicates to me that there is the possibilty that the OD band was slipping (only one of a few possibilities) under higher loads. Knowing that other techs have found concerns with the servoes leaking past the plunger, I'd probably spend the time to check the servo bores in the trans case....

What can make diagnosis extremely difficult is being unable to recreate the concern using "normal" conditions....

HTH

Jim -

That is a whole lot more info than I had before, and I thank you for taking the time to pass it along. Though I didn't mention it, I did ask the shop to drop the pan to replace the filter, as part of the follow-up. Don't know if that was needed, but it sure didn't hurt.

Thanks again

Bill

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Jim Warman wrote: