Well, it had to happen sooner or later, I suppose.

Was driving along from point A to point B this afternoon, and noticed that the engine seemed to be ... revving rather freely. It's been a bit luggy lately, in higher gears below 2000, so I let off the gas and pulled it from D into 3.

No difference. Tried N, revs as expected, back to D, still revs the same way.

Coasted it off into a parking lot, parked. Still won't pull in gear. R, either.

No blinkenlights, it was in Sport, and it was still there.

Pulled the codes, and they were the usual collection which have nothing to do with the tranny, usually, except a P1884, about which no one ever seems sure. I see it a lot anyway. (I have a collection which are secondary to one or more bad O2 sensors, which I've been too poor to fix, being mostly unemployed the last year.)

Towed it to my mech, he checked the ATF level which he says is fine, and checked the shifter linkage, which he says appears to be moving fine.

The dash indicator tracks the shifter, so I assume the WXYZ switch is a) connected and b) working.

I tried running the transfer shifter back and forth; it seemed not to be shifting as it usually does (I don't run low much, you understand, but I do usually use it every couple of weeks to pull me through the carwash, and it worked fine last week when I did, and since.) I could get it from H to N, but N was sloppy, and I didn't seem to be able to get a good detent in L. So I pushed a little harder. It felt like it... had been overcenter, or a fork hadn't been seated on a pin, or *something*... and when I pushed, it jumped back to where it would normally sit, and I could then shift both ranges and N.

Didn't help, alas. Since the failure, there's been no indication at all between the engine and the wheels of any contact, in either range, in any gear. Park pawl latches, the transfer case interlock works, the neutral start switch works, the brake pedal interlock works. But no, y'know, torque.

So:

1) Is this a fully-electronically shifted automatic? Is it possible this could be a failed cable or connector or ECU, or *something* less expensive than the several grand a rebuilt transmission is going to cost me?

2) What (if anything) is the next diagnostic step?

3) Does anyone have a reader that will read the TCU that I can rent, borrow, or steal, anywhere near Largo FL? (I've had a Faultmate in my plans for some time, but it hasn't happened yet.)

 

Yes it is electronic. Depends on the tranny computer, cables, connectors, grounds, etc. Good thing is that blown clutches usually foul the fluid, plus go out in one direction, such as forward. Leaving reverse working.

 

When was the last time you changed the ATF/filter?
And what were all of the code numbers that you have dismissed as not important?

 

I would think the transmission computer should throw a code.
If you are leaking fluid out and you got too low, the transmission may not work in certain gears.

The electronic parts just pulls in solenoids.
If the battery voltage is too low - this will not happen dependably.
You should get a low voltage CEL code.

You could try to change your battery or check the alternator.

The transmission also needs fluid sucked in via the trans filter into the pump.
There must be pressure.

If you are just starting it in the morning and you hear a strange gurgle, then
the pump is getting air into it.
I had that from low fluid.

Or your flex plate broke off and you have no mechanical coupling to the transmission from the engine.

If someone stole a drive shaft whilst it was parked, then it may not move at all.

 

And from the workshop manual, page 617 of 1529, the 1884 codes relate to multiple CAN Buss messages that can need an additional level of scanner software to read.

 

Savannah Buzz: Nope; nothing in either direction, as noted; this is why I think it's electronics-side, not hydraulics. Fluid was checked; needed about 3 oz.

Mike: It's been long enough that it needs to be changed, certainly; over a year, probably over 2 years. But I want to graft the arm back on before I trim the fingernails.

And I didn't "dismiss as unimportant" the other codes; I said they were the same codes it's been showing whenever I've checked it before. In order (presumably reverse-chron, as they come out of Torque/Android):

1884 102 445 448 135 155 141 161 340 1590 134 154 140 160 1300 1319

jfall: nope, fluid was up, and no pull-in to any degree in any gear. The battery is about 2 months old; it's the top of the line Diehard Platinum AGM; new starter too, and the starter spins like a bastard, so I have no reason to believe the battery voltage isn't staying up, but I didn't actually meter it. I was, as I noted, *driving down the road* when it failed; pretty sure no one stole my driveshaft. :-)

There was, FWIW, no notable noise when it died; I was on a quiet road at 30 with the windows open, I'm relatively sure I'd have heard a flex plate breaking, somehow.

And yes, Savannah, I had seen that 1884 might be a supercode; hence my inquiry about smarter scanners than mine.

 

These trannies are a very temperamental beast, I have one in my BMW 540i (zf5hp24) and had troubles with the torque convertor. Had to drop the trans twice to replace TC with a stall convertor, and then solenoids.... had to drop it twice because I didn't have the pick up for the crank position sensor lined up on TDC... big pain it the ars. Good luck, Ill be watching this thread and inject any info I can hat will help you.

 

Yeah. Well, a local (Sarasota) has a 5hp24 just out of rebuild, though unknown mileage, for $300, but until I'm pretty sure the problem's inside the power bubble, rather than computer control or cabling, I'm not gambling.

 

Late word from the transmission shop is that 1884 specifically means the ECU can't talk to *some* other controller on the canbus, though it's not clear which one that is, that the AT should be able to engage in D and R even if it has no electronic connections at all (does anyone want to debate that about the ZF auto?), and that this might well be the transfer case, after I recapped to him my description thereof, above.

He's pulling the case to check, since he'd need it out anyway to pull the transmission.

 

I would find the transmission controller and see if you can clean up the CAN Bus connection.

Maybe get the radio code handy.
Then pull the battery cables off.
Put the cables together when they are off to clear all capacitors.

And reboot the controllers by putting the battery back on (With the HOOD switch disconnected).

Long shot.
But...
It is cheap to do time wise and costs nothing.