No reverse 2wd or 4wd high but ok 4wd low

[edseven]

1998 Explorer 4.0, 5r55e, 4405 180K miles.

Trying to fix this problem. No reverse in 2wd or 4wd high but ok in 4wd low. I replaced the original xfer case with a junkyard one but still the same problem. Then I did the TSB re:5r55e vb diary including replacing the EPC and boost valve. No help. Hoping that the junkyard xfer case was junk I put in a rebuilt case and still the same problem.

I'm guessing this is a xfer case electrical problem but that's just a guess. Can anyone give me some direction as to why I get reverse in 4wd low only??

 

[Glacier991]

I will await more informed Transfer case guys to answert, but if you have in
4Wd-L it ain't the tranny.

 

[gijoecam]

When you replaced the case with the junkyard unit, did you replace the shift motor too, or re-use your existing motor? If you replaced it too, then there are other electrical gremlins to start chasing. If you re-used your existing motor, I would consider it the primary suspect. It sounds like the motor is stopping in the neutral never-never land instead of 4high. IIRC, the rear output is a direct drive off the input if the system is in 4high/auto. If that portion was broken, it shouldn't drive in 4 low either.... the fact that it does makes me think that the t-case is in a neutral position.

To troubleshoot it, make it 'no-go', shut everything off, pull the battery cable, and remove the shift motor. Look for the pics in the useful threads of where that shift shaft should be pointed (towards 4high of course) and see if yours is there. If not, your motor is incorrectly positioning the shift shaft, and you'll need a new one. (Turning it manually to 4high and seeing if it'll drive then should verify the diagnosis) If the shaft is correctly positioned, the t-case is fubar internally and needs to be torn apart. Could be a worn shift shaft or other issue, but parts are available.

Good luck!

-Joe

 

[edseven]

I think the shift motor is ok. The motor shifts from high to low and back. I did pull the motor and the shaft was pointing at HIGH. I manually turned the shaft to neutral an the truck didn't move. I manually turned the shaft to LOW and the truck move in drive AND reverse.

I do have my old case. Guess I'll split that open and try to find out what the difference is between high and low in reverse. Drive works in both high and low. Only reverse is fubar in high.

 

[gijoecam]

If the motor pointed at high, it sounds like you have the infamous shift rail problem.... IZ Waxk knows more about that... he should (hopefully) be back around in a bit to help out.

IIRC, either IZWack or ??? had the original problem... Run a search for Omega Machine and there will be a couple threads....

-Joe

 

[edseven]

How does the shift rail prevent reverse from working in high but not low? Is it possible I'm getting reverse in low only with the front wheels?

I opened the original xfer case tonight. Had a shift pad in pcs but the fork and the oil pump looked ok. However, the shift rail boss looked oval even from just eyeballing and the rail rocks to and fro a good deal.

 

[edseven]

If the shift rail problem can prevent reverse in high but not low can I just remove the 4wd components in the xfer case and make it 2wd?

 

[edseven]

make sense?

4405: brown wire energizes the xfer case clutch in 4wd high and low, the shift fork moves the range gear from high to low. Therefore:

2wd = shift fork in high gear = towards front of case AND no power to clutch
4high = shift fork in high gear = towards front of case AND clutch powered
2low = shift fork in low = towards rear of case AND clutch powered

I get no reverse in 2wd or 4high. If my shift fork shaft is loose in the case because of wear then the fork is not holding the range gear in place. In drive this isnt much of an issue as the gear is turned into the planet because of the cut of the gear. However, in REVERSE, the range gear wants to back out of the planet. Because the shaft is worn, the fork cannot hold the gear in place and it backs out but not enough to get low gear but only enough to get neutral causing no go in reverse.

In low, the shift fork is already pulling the gear towards the back of the case therefore I still get reverse in 4low.

The fix is then to bushing the shift fork rail or convert to 2wd by keeping the range gear locked into the planet.

Make sense?

 

[gijoecam]

That sounds like it makes perfect sense... IIRC, that's almost the description that I've seen described on here before by whomever it is that I can't remember yet LOL!

edit: Found it! Glacier991

http://www.explorerforum.com/forums/showthread.php?t=155458&highlight=omega

Your symptoms definately fit the diagnosis. Did the replacement case fix it?