O/D Light Flashing, no codes.

[JamesGTRS]

I have a 2006 Ford Expedition where a new problem just cropped up. It has 170k miles.

It has been just fine till today. We recently just took a 600 mile road trip over the last 2 days, no problems at all. No problems in the months and weeks before. No indication anything was at fault. We even went out earlier in the morning and everything was working just fine.

Went to take my son to work and and there was no issues, but at a stop light when it turned green, the Expedition did not move. I would have to really rev it up to 2500-3000 RPM and it would move forward very slowly. I can get it up to speed lightly feathering the throttle, but when you stop it doesn't even feel like it's in gear. Eventually the O/D light starts to flash.

Reverse is just fine, put it in R, it gets right into gear and it's good.

I've had transmissions go before in other vehicles, and it gradually goes, I've never had it fail in the middle of a drive so suddenly.

I've checked the fluid, it's a little over full but not bad. If it was the issue, I would think I'd have problems in reverse too? I've reset the computer by pulling the battery cables for a little bit, it didn't seem to make a difference.

1 - Is there an easy way to read the transmission codes?

2 - What else can I check to see if I can remedy this, or do I need to take it to a shop to get it checked?

We have had some fluid leaks over time and I have fixed them before it got to low and added new fluid. I feel like in the last 50k miles I've probably replaced most of the fluid in that time.

 

[whtbronco]

A good OBDII scanner will read the codes as will FORScan. FORScan is available very inexpensively, but does require that you purchase an ODBII adapter.

My past experience similar to this was related to a pressure issue on a GM trans. I found that selecting 1st gear also resolved the issue since the transmission line pressure increased by 30psi in 1st gear compared to Drive. Line pressure on that trans was also increased in Reverse compared to Drive. I installed an improved boost valve to resolve the issue. Not sure this will help, but trying to manually shift into 1st gear is free to try.

 

[JamesGTRS]

I have got the 2 month trial license for ForScan and my PC obdII adapter will be here tomorrow so I can test and see codes.

I also have my transmission pressure testers, which I will connect as well. I found an ATSG manual for the transmission online that gives me some troubleshooting to try. One item in that troubleshooting manual.

"Transmission slips or chatters in forward gears, reverse is ok". It says it's a partially clogged shift solenoid if the pressure is not between 55/75 on the pressure line and the forward clutch line.

I will test tomorrow an report back.

 

[JamesGTRS]

ForScan says "P0732".

Possibilities:
- Internal transmission failure, I don't think this is it. No noise, no clanking, it just stopped.
- Valve body issue, maybe dirty?
- Low transmission fluid level, Nope. Not low.
- Contaminated transmission fluid, maybe, but I doubt it.
- Faulty shift solenoid, I am thinking it's this.
- An issue with the shift solenoid’s circuit. I doubt it, but I will check the wiring.
- Malfunctioning transmission control module or powertrain control module, Doubt it.

Next, check line pressures. If they are different, it's the solenoids. If they are the same, it's probably new transmission time.

 

[JamesGTRS]

Tested the line and front drum pressure.

Line: 78 psi.
Front Drum: 45 psi.

It's the solenoids. Going to pick them up now, install it tomorrow.

I'll post if this was the solution.

 

[JamesGTRS]

Got the pan off...ooo...nasty.

Lots of material in the pain, despite every leak I've seen and it dripping out of the pressure ports being clean, I can see why the solenoids would fail. That fluid is not going back in.

It's not as bad as our Mercury Monterey minivan we had when I replaced the fluid in there, that was a disaster. A few months later the transmission started to slip after replacing the fluid.

It still drove a year or two later before the fuel pump died. I hope the Expedition does not see the same fate.

 

[whtbronco]

I think trans fluid should be changed far more often than recommended. Changing it all is not as easy as it used to be since the drain plug has been removed from torque converters. I changed it all at around 50k as I recall. Ever since I just drop the pan every 2 years which is almost half and it's always nice and red. I change the filter every 4 years. That may be excessive, but it has worked well for me. My trans has 302k miles on it thus far.

 

[JamesGTRS]

Well, none of that worked. Still slipping, no change. There is either a blockage somewhere else in the transmission or there is damage in the front drum.

This is a $1500-$3000 repair at a shop, and no shop in my area can get it done for at least 3 weeks. So for now it sits until I figure out what to do with it. Not sure it's worth putting that kind of money into it.

Anyone ever rebuild a 4R75E? Is it "easy"? Maybe the words I am looking for is "straight forward".

 

[whtbronco]

Well crap, I really thought you were on to something with the solenoids. The PCS seemed very probable.

I have not rebuilt a 4R70W or 4R75E. I did a C6 years ago, but that's not much help. I have watched a few tear downs on the 4R7xx trans and it really doesn't look that difficult. I have also been tempted to buy a used one and rebuild it. The parts are not that expensive.

I did that with my transfer case and found out it really isn't that difficult, obviously much easier than a transmission though. I also found in the end that I decided to remove the used and rebuilt transfer case, proceeded to rebuild my original t-case and reinstall it since mine had so much less wear despite higher mileage. So this experience kinda makes me weary of possibly spending $5-600 to rebuild a used transmission only to find out I want to rebuild mine anyway. Maybe the money is worth the experience though. So much easier the 2nd time.

 

[JamesGTRS]

I've watched a few videos myself of seemingly very difficult things an they don't see that difficult. Going to ponder for a bit. I have time. Thanks!

 

[mbtech2003]

did mine a few years ago, dropped transmission and replaced all clutchs and bands, not too bad. got all parts from https://www.oregonperformancetransm...EFuB0jrVXo6p5tYN9pD97slsl8RLfwspOnE1Feo1OJonD

as well as a shift improvement kit from trans-go, I also did a few of the J-Mod drills in the NEW tough shift plate. took a 180k mile transmission and now shifts quick and firm. I have an automotive repair background. IF you are not tech savvy don't do this and just have a shop do a full build. It cost me 900 in parts for everything I did... plus my time... For 2K more to have a shop do it. let them. and have a warranty. I know have 205k on it. I didn't replace any seal/pisot/ bushing in the trans. but did all the accumulators, and springs. good luck.

 

[whtbronco]

@mbtech2003 I'm intrigued and maybe others are as well. Why go through the effort to replace many of the hard parts inside the transmission and not replace the seals? Were they simply in good shape and didn't warrant replacement.

My old C6 didn't really need a rebuild it needed new seals. After almost 30yrs the seals had gotten hard and it was struggling to build pressure as a result. So while I was there I went ahead and replaced the typical wear items in it.

 

[mbtech2003]

Didn’t feel the need. I blew the reverse band backing up a 8k lb trailer in reverse in 6” of mud. I have horses and was dumping the manure trailer at a local landscape place. I wasn’t having any issues with it until then. Also need the truck back in a weekend. If it was not mine I would have so my chance I took. I wouldn’t recommend it. lol. Trucks all rusted out anyway so if it didn’t work I was just gonna trade it in or junk. But it’s still going on strong when something else dies in it I’ll retire it.

 

[whtbronco]

Well that makes sense. Thanks for the explanation.