Understanding my Tranny

[Robrt32]

I was going down the interstate this morning and my truck dropped a gear.. I first thought, Well Ive lost overdrive like Ive heard others say BUT If I shift down one it kicks down another gear.. SO from my understanding I have a 3 speed overdrive trans with a lock up torque converter, is that right? Since it kicks down when I shift down one, Did my converter stop locking up? ALSO , When I get to 65 I get a Check engine light, soon as I slow back to 55 it goes out. This has to be related or a big co-inky-dink.. The fluid levels are full, it shifts perfect in every gear except for the final one.. My Tach use to be just below 1500 @ 55 now I'm just under 2 grand @55...... I got to go back to work now.. I will check replies and answer any questions later this afternoon.. Thanks in advance for insight

 

[Masterd]

You probably lost 4th, and now you have a 3 speed with lockup. The same thing happened to me.

When you're cruising at 60+ on the highway keep your foot on the gas, and tap the brake pedal, if the revs go up, that means the TC unlocked, meaning the TC is working and 4th gear is dead. If the revs dont jump, that means the opposite.

 

[Robrt32]

alrighty thanks, I will check that out in the morning

 

[Robrt32]

TC isn't working.... What are my options to fix it? I get good gas millage, I hate to loose that IF it could be fixed fairly easily...New TC?

 

[Shen2187]

New TQC is just about the only option..

 

[Robrt32]

I will price check a few today...If there is room. I SHOULD be able to just slide the tranny back and not have to drop it all the way down to change it..

 

[Masterd]

New TQ is NOT the only solution.

It could also be the solenoid that controls when the TC locks....

 

[Robrt32]

Is there a link that shows me how to test it?

 

[Robrt32]

also, I have another complete Exploder for parts... Is the solenoid something I could swap?

 

[Masterd]

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This pic shows the electrical connector (circled) and the two solenoids. One controls 3-4, and one controls lockup.

I dont remember if you have to pull the pan and VB to get them out. As for testing the solenoids, they are both just on/off....they either work or they dont when you apply voltage to them.

 

[Willard]

That picture is not accurate. That is not the standard A4LD transmission that we have. That is and A4LD-E, used in vehicles over seas after the A4LD was not made here in the states. Your transmission has a vacuum modulator where it is circled in that picture. To access the solenoids you must drop the pan and you will see the two right there. Information on testing them and what they look like can be found in Glacier911's A4LD rebuild diary which is a sticky in the transmission forum. If the TC is not locking up, that solenoid is very likely the issue. Testing and replacing that would be my first plan.

 

[Masterd]

Oops my fault, that is the A4LD-E...but the servos are still in the same place.

Heres one with the vacuum modulator:

 

[Willard]

Yes but those servos are not what is likely causing this issue, it is the electronic solenoids that activate them. The solenoids that activate them are in the valve body, the servos are what physically tighten the bands to engage the gears.

 

[Masterd]

The servos can also dry out and leak...the exhaust cooks them.

 

[Willard]

You are right, but when it happens suddenly like this, it tends to be something electrical. I wouldn't think a servo would normally just let go all the sudden, it would be a little more gradual and change under certain conditions. But if the solenoid checks out that would be the next place to look, however i don't think it's as likely.

 

[Robrt32]

I guess I'm gonna pull my spare tranny, I got a tranny guy that will rebuild mine for less than half what shops charge and he is GOOD.. I don't wanna put a tranny in I'm not sure how many miles are on AND EVERY time Ive seen a pan come off and new oil added back , the tranny went out.. I'm not puling the pan. I understand some people do it and all is fine but Ive never had that kind of luck!....SO, I will run it like it is while getting a fresh tranny ready to go in

 

[Willard]

Perhaps before you go that far you need to make sure the TCC solenoid is being triggered to lock it up. It is possible that something happened not related to the tranny causing it to stop locking up.

 

[Robrt32]

Does this help any, TODAY it worked fine... ALL I done different was, I was in a hurry and ran the sh$t out of it.....

 

[Masterd]

Does this help any, TODAY it worked fine... ALL I done different was, I was in a hurry and ran the sh$t out of it.....

Servo