solenoid block test?

[Ironhead Dave]

Early 02 Explorer 4x4 150k miles. It started acting like it was popping out of gear. I wiggled the gearshift and revved it a little and it went back in and got me home. Later, it did it again with my wife and she limped it home. I pulled it in the garage and it sat for a week. I tried to move it and now nothing. you cannot feel it shifting into gear. There is no 'clunk'. I checked the fluid level and it seemed ok. I had all the wheels off the ground and ran it though the gears and it acted ok so I put it on the ground and tried it. Like the tranny fairy fixed it for me or some other nonsense. It backed out of the garage fine and when I put it in drive, nothing. If I rev it up, I can feel it chatter a little and try to move. Shut it down and pushed it in the garage.

I have since dropped the pan, filter, reverse accumulator, solenoid pack and the valve body. Nothing obvious. I am no transmission guy though. I know about enough to be dangerous. Fluid looked decent. Just some fine particles on the magnet.

I have a friend that is a Ford mechanic that is having me do a bunch of checks for things he 'has seen' happen which is fine but a little more than I care to get into. He suggested that the soleniod pack may be bad and to replace it. That's big $ for a maybe. Is there anyway to do an ohm check, etc. to test it before buying a new one?

I plan on tightening the bands but it doesn't make sense that one minute I am driving home from church, I turn the corner and then both bands let loose.

Now to add to the equation, I got stuck in the snow (4x4 is out) and I rocked it back and forth and got on it a little hard spinning tires and such to get out. I did not slam it back and forth from reverse to drive but there was some minor abuse going on. This was about 3 days prior.

I also have full service records from the PO who bought it new and I cannot find where the fluid/filter was ever changed.

So my actual question was about testing the solenoid pack but if there are any other thoughts, they are welcome. My friend wants me to drop the exhaust and check the band accumlators (?) whatever the round caps are on the side oppisite of the band adjusters. I see a can of worms with rusty exhaust etc.

Could this be something as simple as broken down fluid that will no longer create enough pressure? I had that happen with a hydrostatic trans once on a mower.

Sorry for the 'novel'

Dave

 

[PopRichie77]

It's not the fluid. Those round things opposite the band adjusters are the band servos. It could be the solenoid block. Did the OD light flash, that indicates that a transmission code was stored in the computer and needs to be read. Doing an ohm check only proves that the coil in the solenoid is good or bad, does not prove that the hydraulic part of the solenoid is good. You need to do a trans pressure test for line pressure.

 

[Ironhead Dave]

I saw nothing when I was driving it but I wasn't looking either. My wife said the message board said to check transmission. My cheap reader only says P1700 Transmission system fault or someting similar. I have no way to get it checked for better readings since it is in pieces in my garage.

Will Autozone's reader do tranny codes or does it need to be a dealer? The nearest dealer is about 30 miles away but I have a AZ just up the street. I could maybe talk them into stopping by.

My buddy told me to check the band servos because he has seen the rods break on them before. I am definitely not questioning him but it is a lot to go through if someone may have another avenue to check out.

I have a FSM for it. Does it explain the procedure for a trans pressure test?

 

[PopRichie77]

Both servos would not break or stop working at the same time. Manual LOW does not use these servos..
Look in the stickies in the beginning of the forum, you should find information on how to do a hydraulic pressure check. However it must be all together.
This also could be your problem----- http://www.explorerforum.com/forums/showthread.php?t=322684

 

[Ironhead Dave]

PopRichie77. If I understand right, the one way, if bad, will allow travel in one direction but not the other. I had reverse for about 50 feet and then neither forward or back. I really hate to put it back together to test it only to tear it apart again. I am considering putting aa solenoid block on it and hope that is it. If not, I can further diagnose it from there. Or does that sound like a waste of $ at this point?

 

[PopRichie77]

Did you try manual 2 and 3rd gears?

 

[Ironhead Dave]

Did you try manual 2 and 3rd gears?

To be honest with you....I am pretty sure that I did with no success but I cannot say for sure. I know that reverse, OD, and 1st are gone.

 

[PopRichie77]

If a pressure test is ok then probably the O/D sprag (one way clutch ) is bad. Requires trans removal and disassembly to replace. Pull the solenoid block and look for a bad gasket but they don't usually go bad.
The 4 shift solenoids A,B,C, and D are 16-45 ohms.
The 3 pressure solenoids A,B and C are 3.3-7.5 ohms.
TCC solenoid is 9-16 ohms.

 

[Ironhead Dave]

If a pressure test is ok then probably the O/D sprag (one way clutch ) is bad. QUOTE]

I will try to reassemble and do a pressure test this weekend. Is there a way to test the sprag?

 

[JK080]

The symptoms of a failed one way input sprag (overdrive sprag) is no forward or reverse, but it will move in manual low and manual 2nd.

 

[Ironhead Dave]

The symptoms of a failed one way input sprag (overdrive sprag) is no forward or reverse, but it will move in manual low and manual 2nd.

Thanks JK. I have no movement in manual low so hopefully that rules that out.

Like I stated earlier, it will move but only if I almost redline the truck, it will 'chatter' (no actual noise, just grabbing sporatically) and it has to be perfectly flat. No bumps or incline. If I put a couple of people behind and push, it will move....barely.

 

[Ironhead Dave]

If a pressure test is ok then probably the O/D sprag (one way clutch ) is bad. Requires trans removal and disassembly to replace. Pull the solenoid block and look for a bad gasket but they don't usually go bad.
The 4 shift solenoids A,B,C, and D are 16-45 ohms.
The 3 pressure solenoids A,B and C are 3.3-7.5 ohms.
TCC solenoid is 9-16 ohms.

Do you know the pin configuration on the plug to check these?

 

[PopRichie77]

I sent you a PM, check it.