A4ld Overdive issue, please help

[Masterd]

Well today I was getting on to the freeway in the X, and noticed that OD wasnt locking in. Instead I heard a LOUD howling noise from under the floor.

My first thought was the TC, since if I moved the shifter from OD to D, the truck would go back to acting fine, minus Overdrive.

But I realized that I think the TC locks in the D position as well, so would my problem / noise + lack of OD be 4th gear???

 

[BrooklynBay]

You might have internal damage in the overdrive section on the front planetary or the one way sprag.

 

[Masterd]

Could something like this just happen suddenly?

Because I drove to my destination in OD, and later that night had to drive home in D because OD was making noise and wouldnt lock.

 

[Tbars4]

...You might also look at your transmission's electrical harness (drivers side) and see if it has met the exhaust...

 

[BrooklynBay]

The fuse would have blown if it got melted from the exhaust. The A4LD has a 3 wire harness (88-up). One wire is a constant positive connection, and the other 2 wires are computer controlled grounds which control the TCC, and 3-4 shift solenoids.

 

[Masterd]

I didnt see anything unusual about the wiring underneath on the driver side.

Just the usual oil leak, and a little atf, from the VSS it seems...

PS - I drove it on the freeway in OD today, and it made less howling noises, but it wont go into 4th....TC still locks (i can unlock it with the brake pedal, so I know the tc is locking), but no 4th. I can start off in OD position, so no slipping there either.

 

[Masterd]

So will my 4.0 care if I'm running ~3k @ 75 mph with no OD, or am I fine to run it that way? Remember its got 288k on it.

Im glad I have the 3.08's in this case.

 

[BrooklynBay]

You could rebuild it now or wait until it breaks down.

 

[Masterd]

Whats the life expectancy out of an A4LD with no OD?

 

[BrooklynBay]

It depends upon other internal parts. Take a look at the A4LD rebuild diary sticky for more information. Project Frankentranny would be recommended after you read the diary thread.

 

[Masterd]

Brooklyn,

If its not too much to ask, can you point me in the direction of ways to test the electronics controlling 3-4 shift, and TCC lockup?

 

[BrooklynBay]

Those solenoids are only on/off solenoids. They don't require any special testing tools. They are not modulated.

 

[Masterd]

Where can I locate them at?

 

[BrooklynBay]

Check WWW.TransmissionPartsUSA.Com. Type in A4LD when you search the site. It's usually one of the first things to come up.

 

[Masterd]

Hey brooklyn,

Is there an easy way to drain the tranny fluid. before I take the pan off? Does the A4 have a drain plug anywhere?

Id like to drop the pan and look for evidence, and also clean the solenoid screens.

Thanks!

 

[BrooklynBay]

You could use a manual vacuum pump to pull the fluid out. This is the big version, not a small hand pump. I have a product review on this: http://www.explorerforum.com/reviewpost/showproduct.php/product/321/cat/500

 

[Masterd]

...I really wish it had a manual drain port or something...

 

[BrooklynBay]

You could install a drain plug after you drop the pan.

 

[Tbars4]

...This might help..
http://explorerforum.com/forums/showthread.php?t=206353

 

[Masterd]

So any method specifically for removing the pan with the fluid in it?

Front or back first