After getting a good handful of results on my search of overdrive light, I kept seeing that a normal code reader can't necessarily grab the code that the overdrive off light is flashing.

So: on a 2000 Expedition 4wd, overdrive light was flashing (3/4 second on, 3/4 second off) on my way to work. Got home and scanned and had a pending P705 code.

Is this the code that is being represented by the blinking OD light or is there another code that I can't grab with my OBDII reader?

I bought it recently so I am not familiar with "normal" shift points of this transmission. Also, are there four distinct gears plus lockup or are there three gears plus lockup, or four gears that can be locked in 2nd, 3rd, or fourth...etc?

Thanks!

 

A P0705 code will flash the OD light. That is probably the one you are looking for.

You have either a 4R70W or a 4R100 transmission. Each of them have four gear ratios, plus a torque converter clutch. The lock strategy is different on the two transmissions, but both normally lock in third and fourth, while the 4R100 can lock in first and second when the go pedal is on the floor.

 

Great info. Time to do a road test and see what I can come up with.

 

Check and see which transmission you have.

The P0705 code indicates that the signal(s) received from the TR sensor were not logical. The TR sensor contains a four-section portion (along with other functions) that sends a set of four signals back to the PCM to tell the PCM what position the shift lever is in. If any of these four connections or the underlying switch section fails, the PCM cannot properly determine the position of the shift lever.

I'd start by pulling the connector on the TR sensor and inspecting it for corrosion or damage. Clean it and reinstall with some dielectric grease and see if the fault comes back. If it does, I'd replace the sensor.

Ford's DTR and TR sensors have earned a reputation among transmission specialists for being a PITA.

Steve

 

Trans door code is E, has factory drain plug, 20 bolt pan. Trans tag is the following:

Just took it for another road test, no light. Automatic upshifts seem what I would consider normal and I also have normal manual control as well. There are two problems that I seem to have found though.

When in OD and letting off the gas, decelerating through a subdivision or something (dropping from 30mph), I can give it gas and it doesn't seem to be in any gear per say...just seems like I am loading the torque converter and RPMs will go up. No clunking or freewheeling though--I am up against some load, it is just that speed doesn't increase unless I hold it at the point where the torque conv stops "flashing" and then it will continue in its gear. I would guess it flashes an additional 800RPM or so.

The second problem (which might have caused the code to begin with) is that my shifter is definitely not smooth. It needs to be lubed somehow I would think. I popped the coverplate of the top of the steering column, saw the hold down bracket for the shifter shaft on top, then it goes to where it has the spring-loaded lock (almost like a woodruff key from the angle I could see it).

Truck has 177k so I could understand if it was worn...but being stiff seems like the opposite of what I would think.

After the road test (of course I had to make sure the exhaust was hot while disconnecting the trans switch!), I pulled the connector. Definitely a tight fit and someone had already had it off before since the lock tab was broken. I need a new pigtail for that. One of the 2 bottom terminals had a lot of corrosion inside the cavity. Cleaned it with CRC electronic cleaner and a brush pick and then put the connector back on with dielectric grease. That is when I noticed the connector wouldn't snap and that it had been broken. So I tried jamming it again and it was as far as it had been when I pulled it off judging from the dirt marks. Now here's the kicker...

Looking into the cavity of the switch, the lowermost right pin was bent inward. My guess is that the pin was bent previously and that is why the connector cavity was corroded. Unfortunately when I moved that pin to align it straight, it was as floppy as a joystick. Either I crushed it or it had been crushed previously but like I said, with the corrosion and broken harness end tab, I would guess it was already bent to begin with.

GTG to work in 30 minutes but I am getting ready to give it a quick road test to see if that pin might have something to do with it.

P0705 has still been pending ever since I scanned it and the OD light has been off.

 

Was going to try to solder the pin back into the switch but I had to break the switch housing in order to get the part off that surrounds the shift shaft. Got an OE part from AutoZone (Wells usually did Ford parts and then they literally grind off the Ford emblem and long part number). BTW, the pin that was broken/connector socket that was corroded goes to TR1 in the PM. I am limited to EBSCO online right now and it doesn't list what that pin is...any ideas? If not, I can give AllDATA a shot tomorrow.

Anyhow, the shift lever is much smoother so disregard everything I was talking about with trying to find out how to grease the shift shaft running along the top of the steering column.

Haven't road-tested it long enough to see if my trans seems to shift normally or not though. No pending P0705 anymore. It was likely due to the fact that the switch was so gummed up, it was not making correct contact all the time.

Now I just have to fix my D/S exhaust leak to get rid of my emissions code, get the rear wiper motor working, and the truck should be good as new...plus 178k

Thanks.

 

TR code = E is 4R100

Signal 'TR1" is one the four signal lines to the PCM that is uses to determine shifter position.

Sounds like you've probably fixed it...

Steve