2001 Explorer SOHC 4.0 liter. I have the dreaded O/D off light with a side order of a clunking noise when the tranny is in any gear. I have searched the forum for this and have read a lot that leads me to believe it is some sort of electrical issue. There are no engine codes and I refuse to pay someone to read the trans codes until I at least look around first. I will keep you posted as I try to solve this newest problem. Any comments will be appreciated. Thanks.

 

Clunking noise with vehicle MOVING, in any gear, or while standing still with engine idling, with selector in any gear?

"O/D OFF" light solid on, or flashing on and off?

Unlikely electrical issue can cause mechanical clunking noise.

 

No noise in park or neutral. Noise is in any gear, while moving and not moving, while idling and under light acceleration but the noise is not loud enough for me to tell if it is there at heavy acceleration or higher speeds due to road/engine noise and my pee poor hearing. The light is flashing and all this only happens when the vehicle is fully warmed up. Trans will not up shift under moderate or heavy acceleration unless you let off the throttle, while under light acceleration it shifts normally.

 

No expert, me, but without reading code causing flashing O/D light, it's a crapshoot. Off the top: sluggish but not inoperative, control solenoid, likely a pressure control solenoid (there are several, if it is a 5R55S or W).

Does not sound like an issue with Torque Converter clutch, unless broken part(s) exists within it, causing noise. Such noise would likely be present in Park & Neutral, as well as in gear.

Lack of upshift while under open throttle again points to improper control pressure, or possibly shift solenoid(s). Here, USUALLY only one shift is affected, as there are separate solenoids to bring about each shift (1-2, 2-3, etc.). Shift scheduling in these trans. no longer only mechanically-dependent, like old days- (then driveshaft speed {governor}, and engine load (vacuum) determined shift timing. Now, computer (PCM) constantly reviews those factors, plus others- (eng. coolant temp., barometric pressure, trans. fluid temp., exhaust emissions quality, AND the important shaft speeds within the trans, relative to one-another). This last tells PCM whether given relative shaft speeds are appropriate to one another for the conditions being imposed on the transmission. See? A crapshoot! But, you get the idea. Be aware, please, the flashing O/D codes are usually not readable by most aftermarket code-readers, as they look at stored info for "Check Engine" light only. Some of the up-to-date parts stores might by now be able to read them, not sure. Auto-Zone does it free, but maybe only "c.e." codes.

Any other malfunction hints present? Sorry I can't be more concrete in my answer. No transmission GURU or expert. impish

 

Thanks for the response. It is a 5R55E trans. The only trans shop in my area that I trust is not surprisingly very busy as usual but I left it there for them to diagnose. I looked around for possible grounded wires but did not find anything. I would normally do this myself but I am still very limited in what I can do because of broken ribs after rolling my 4 wheeler 2 weeks ago. Again thanks. I will repost when I know more for the education of others.

 

Well here is the final outcome. The torque converter came apart internally and sent aluminum thru-out the system. It took 5 hours to flush it out of the cooler, a new pump and converter and a complete rebuild of the trans to fix the problem. Two transmission rebuilds in 10 years does not speak highly of the 5R55E trans. Thanks for all the input.

 

Simple solution, get a better cooler, and have the shop install a shift kit. The torque converter likely came apart because it was overheated at least once (the whole trans doesn't necessarily overheat, just the converter) The 5R55e is in fact a solid reliable transmission when it is upgraded. Compare to the track record of other small SUVs (S10 series, Durango, Jeep Cherokee and Grand Cherokee) and you will find the 5R55e is at least as good if not bette than what is used in those. Even the imports suffer in this class, the Honda Pilot has a poor record already, the Nissan Xterra and Pathfinder have other issues that make transmission reliability irrelevant, etc. Only the Toyota has proven halfway reliable, and they have their own issues too, in addition to a high initial and resale price. The high resale is great if you want to sell it, not if you want to buy one.

 

I have no idea why the converter came apart but I cannot think of any reason for an overheated condition to have happened. The trans was upgraded 5 years ago when it was rebuilt the first time. All I have to compare my 5R55E against is my non-upgraded 727 in my 22 year old Dodge pick-up. The comparison is quite dramatic and does not favor the 5R55E. To say the least, I am not impressed. Sorry.

 

Must have been a defect them. The part that just gave way was not a Ford part in all probability.

You comparison is irrelevant, you are comparing a light duty trans designed for small SUVs and light duty trucks to a full fledged truck trans.

I would definitely take the 5R55e over the older A4LD, 4R44e or 4R55e.

 

The A4LD was garbage! I have the 4R70W and its bulletproof..... my truck has 185,000 miles on it and not once has the tranny had to be looked at. Shifts perfectly in all gears and no clunking noises. Truck is 14 years old

 

An unfair comparison it might be but that is as I said all I have to compare it to. It very well may have been a defect but I guess I can't expect brand new Ford replacement parts to be non-defective, and it was a stock 5 year old Ford converter that failed. I love someone that defends Ford's design, while their best advise is to upgrade the original stock parts to get reliability. LOL