Had transmission codes read and came up 2 of them

1 - DTC 335 (which said egr something)
2 - DTC 646 (incorrect second gear ratio)
Antone have any info on what to look for or what to replace w/ these codes in mind???
Sorry this is a 95 explorer 4X4 auto 4.0L

 

1st question: are these KOEO, KOER, or continuous memory CM codes? If you're not sure, review instructions (see "tests" at www.dalidesign.com/hbook/eectest.html if your instructions are unclear). It makes a difference in your diagnosis which part of the test these codes came from.

 

these codes were pulled from a snap-on scan tool, no key on key off ,they are continous memory codes that are blinking my overdrive lite, had problem w/ shifting into 2nd and sometimes overdrive also , so had tranny rebuilt new conveter, fluid, the works, same problem is still present and overdrive lite is flashing again so had these codes pulled from the truck, he had the scan tool plugged into the obd plug inside as well as the test plug under the hood behind the battery ...hope this helps , my wifes gettin antsy she wants her truck back..hahha

 

If I understand correctly, it passed the KOEO test, and those are continuous memory codes. Is this correct? On that assumption:
Before dealing with the CM 335, do the KOER test to see if you get an equivalent KOER code.
As for the CM 646: The transmission has a sensor on the input shaft of the transmission and another sensor on the output shaft of the transmission. From these sensors, the computer can tell how fast each shaft is spinning and calculate a gear ratio. On a '95, you have the 4R44E transmission on which all of the shifts are controlled by the EEC-IV computer. So basically what happens: the computer tells the transmission to shift into 2nd gear, and it knows what gear ratio it should see. It calculates a gear ratio from the sensors and compares the calculated gear ratio to what the gear ratio for 2nd gear should be. If they are significantly different, lights come on and trouble codes are set. Possible causes, and I can't be too specific because I'm not that familiar with the '95 and the 4R44E:
1) The transmission isn't shifting into 2nd gear when told (Since you just had it rebuilt, I would hope this isn't the case).
2) One of the sensors is faulty. If this were the case, I would expect to see more codes (incorrect gear ratio in 1st and 2nd and 3rd and 4th).
3) A bad connection between the computer and the sensors. You will need a wiring diagram.

 

Rob, the 335 is "probably" a bad EGR PFE sensor; very common problem with these engines.

As MrShorty says, the 646 can be caused by several things. The 4R44E shifting is electronically controlled by solenoids. Since the shifting problem shows up when it's supposed to go into second gear (and you've had it rebuilt), I would suspect a bad or clogged second gear shift solenoid. I think it's called "S2", but I don't have my book with me.

This assumes the solenoids weren't replaced with new ones during the rebuild......?

 

Hey, If I can bring this issue back to life....

I also have a '95 Explorer 4x4, EB edition.

I have searched through these threads and looking for an answer myself. I just had the exact same problem: I was accellerating hard down the road and my explorer didn't shift to 2nd gear until 30mph+/- and the O/D light started flashing. I went home and pulled the codes with the Actron code scanner and got codes 335 from the KOEO portion and 646 from the CM section. Now my truck will only shift out of 1st if I let off the gas and go really easy on the gas, in third gear, between 27 & 35. If I go hard on the gas it jumps back up to first gear.

From reading some of the other posts, it seems like the 335 & 646 (or 642 in some other cases) codes seem to be related to each other. Has anyone figured out if the Solenoid is the culprit, or if there is another solution? I need to get this repaired, but it sounds like having the tranny rebuilt may not be the answer...

 

I can't see how engine EGR feedback can be related to transmission shifting. Only possible thing is that at WOT, EGR valve closes and the transmission should be looking to shift down. So if EGR isn't working and transmission has issues, WOT could trigger both codes at the same time. But fordfuelinjection.com lists 335 was a KOEO code that is a simple test at the off condition, not a dynamic test with the engine running...?

I'd try to tackle the issues seperately. I think Mrshorty's analysis is where I'd start.