How to clean/replace 3-4 solenoid on A4LD?

[Ross-N-Chicago]

I've been trying to find out why I lost 4th gear and there are lots of posts/threads on tranny flushes that clog the screen on the solenoid and prevent 3-4 shifting, which is what I believe has happened to me. I flushed mine 3000 miles ago but have replaced the remote 3x and the pan didn't have much clutch dust but there were a few flakes floating around. Still very small flakes at that.

I have done the following:

Replaced vacuum modulator, TPS, O2, low/reverse servo o-ring with the better double lip one, replaced tranny filter and remote filter. Tranny fluid OK.

Do I have to drop the tranny to get at the 3-4 solenoid? Is it difficult to do w/o a manual? Or could it be as simple as an electrical switch that is malfunctioning?

Thanks for your help. Ross

 

[NH25]

Replacing the 3-4 solonoid will require you to remove the pan and the valve body but it should be a pretty simple process. While you are at it you may as well replace the torque converter lockup solonoid since it could be plugged up as well.

After removing the pan you will need to remove the valve body then you will have easy access to the solonoids -they are the two round things that the wires attached to-. You can remove the solonoids by pushing in on the solonoids and removing the lock washers that hold them in place. Then slide the solonoid out and replace it with a new one. Replace the lock washer and put everything back together.

Let me know if you have any problems and I can scan some pics from my manual. Good luck!

 

[MrShorty]

Before going through the trouble of dropping the pan and replacing the solenoid to see if that fixes the problem, try testing the circuitry. As you know the 3-4 shift and the TCC clutch engagement are controlled by the computer. Check for continuity between the computer and 3-4 shift solenoid. Backprobe a connector in the 3-4 solenoid circuit and make sure you have 12 volts with the key on. I've even driven with the volt meter so hooked up and watched for the votage to drop to zero when the computer tells the solenoid to activate. The computer just acts as a ground side switch for these two circuits. Some simple tests like this will help determine if the reason it's not shifting to 4 is because 1) The computer is never telling the transmission to shift, in which case it may not be a bad solenoid, or 2) the transmission is unable to process the command to shift, in which case it could be a bad/dirty solenoidor some other problem in the transmission.
Good luck.

 

[Opera House]

Like I said

Just don't tip it over. There are I think 3 balls and 2 tiny hockey pucks that just sit in the grooves. The seperator plate holds everything together till you can get it on a table. Set it on a towel so if things pop out they don't roll too far. Three spring valves will push on the seperator plate when you remove the screws. If you note where everything is you can get it back togethr without a manual. Only remove the keepers on the solenoids. Then just wash it without removing the spools and tipping it over. I keep saying it but everyone tips them over, it's just natural.

 

[slag]

I'm having a similar problem. I just rebuilt my a4ld but my torque converter locks up and then drops out randomly.. Generally when going up small inclines. I have reset the throttle-tranny cable, checked continuity on my tps (looks good), etc. 1-2 shifts in town are great, its the 3-4-torque converter shifts that seem to "hunt"

I wonder, are the connectors on the solenoids in the tranny polarity specific? I mean, what happens if I plug a red wire into a place where a blue wire goes and vice versa?> This is on a 91 X

 

[MrShorty]

Originally posted by slag
I'm having a similar problem. I just rebuilt my a4ld but my torque converter locks up and then drops out randomly.. Generally when going up small inclines. I have reset the throttle-tranny cable, checked continuity on my tps (looks good), etc. 1-2 shifts in town are great, its the 3-4-torque converter shifts that seem to "hunt"

I wonder, are the connectors on the solenoids in the tranny polarity specific? I mean, what happens if I plug a red wire into a place where a blue wire goes and vice versa?> This is on a 91 X

I'm not certain if the solenoids are polarity specific, but I do know that the wiring diagrams I've seen show a diode in parallel with the 3-4 shift solenoid, so I expect they only intend current to flow one direction, at least on that one.
Even if they aren't polarity specific, switching connectors is going to confuse the wiring pretty bad. If you switched the two PCM-solenoid wires, then the transmission will lockup the torque converter clutch (TCC) when it really wanted to shift into 4th gear, and then give you 4th gear when it really wanted to lockup the TCC. If you've switched the power supply wire with one of the others, I'm not sure what will happen.

 

[slag]

i havent confused the two solenoids, but i am not sure if I have the 2 wires on the correct terminals on each solenoid. Do you know where I could find a picture of which blue wires go where and which red wires go where?

 

[Glacier991]

Red wires to the forward most solenoid, with the 2 wire common (hot) on the topmost connector, blue to the rear most. Actually given the loom setup I doubt you could do it wrong. I am not sure but doubt there is wrong vs right other than reds to front and blues to back. Actually there is only one hot feeding both. They are apparently actuated by the grounds being completed.

The 3-4 solenoid IS a problem child - but the new version from FORD is EXPENSIVE - $179! I'd get a can of brake cleaner and go to town on it in a rebuild (exactly what plan to do) or but an aftermarket replacement ($25 or so) Not sure the pic will help but there is a pic of the solenoids and wiring (poor) in "My A4LD Diary - part 1"

 

[doradexplorer]

Go to matco?.com the online tranny parts house (check someof opera house's posts)
a4ld solenoid kit (3-4 and tcc) was only $30, i put both in when i dropped my valve body
(yeah $900 truck!!)
get new seals as well, valve body and valve body to tranny ( i can't remember any names) as well as the newer style filter and o-rings.
if i had any idea where the receipt was, i would give you actual part numbers, but look around on here and their site
(the thicker gaskest are a little more expensive, in case you have any warping of the valve body)
and prepare to be drripped on!
Scott

 

[slag]

I went to autozone to get my CEL read. It was a code 85--evap canister code for emission control. Defintely not a show stopper!

I bought a TPS (throttle position sensor) while I was there. I came home and took my TPS off and hooked it up to my ohm meter. Instructions are to hook it up and turn the dial and check for erratic readings along the path of the dial. I couldnt find anything wrong after spending a minute or so with it. As I was getting ready to stop, my multimeter spiked a bit and then calmed down.. hmm

Fast forward to today. I did some more checking and it spiked every once in awhile. I tested the new one and couldnt get it to spike. I put the new one in and took the vehicle out on the road after resetting the ecu.

So far, problem solved. The torque converter locked up and at 70 mph, my tach showed around 2400 rpm or so on a few mile test run.

Slag

 

[Glacier991]

thanks for the update - those are always VERY helpful for everyone.