No O.D. A4LD

[DeMo8361]

I just bought this '92 XLT and for the most part, I love it. However, overdrive isn't kicking in. I changed the fluid and filter, still nothing. It goes through all the other gears great, just no O.D. Any advice before I take it in would be appreciated.

'92 XLT
167,000 miles

 

[Glacier991]

hmmm others are better diagnosticians than me, but I am wondering if the OD servo is stuck somehow. Not easy to get to with the exhaust sandwiching it in, but if you could I'd pop the cover and see about putting a new one in (they are cheap, about $7). other possibility is that what you sense as no OD is actually no TC lockup. THAT is controlled by a solenoid, and you can replace that without removing the trannie. I'd guess one or the other. About $30. Remember I said GUESS. Good luck.

 

[DeMo8361]

I'll look into that tommorow, thank you

 

[Charlie's_93EB]

i hope your fix is cheap. i am in the same boat as you, i would start saving my $ because lose of O/D is the first sign of a bad tranny.
i have driven 15,000 miles w/o O/D.
it sucks, but untill the tranny fairy putts one under my pillow at night, i am SOL.

 

[MrShorty]

I haven't got time to write it up completely, but have done so in the past. 1st thing to do is determine if the fault lies in the electronics that control the 3-4 shift or not. Run a search and you should be able to find one of the times I've written up a basic how-to for this.

 

[Dignan]

I have a problem not a solution, sorry.

My problem is that if I put the tranny in overdrive at a stop or at any speed under 35, my tranny slips. It works fine in D, and over 35mph it works fine in OD. Does anyone have an explanation for this?

 

[Opera House]

Slipping in the lower gears in OD but no problem D is usually a problem with the OD one way clutch slipping. When you put it in D, the OD clutch locks (not the one that gives you OD) and takes the power.

As to missing OD, there are a number of mechanical problems it could be. Other than that, look on www.atcdg.com in the tech section under A4LD. There is a screen that can get clogged. Dropping the pan will give an indication if it is a severe mechanical problem or something restricted to the valve body. If you are taching close to 3K at 60, then you have OD problems. Just 300 rpm high higher than normal is probably the TC lockup.

 

[Dignan]

So for mine is there pretty much nothin I can do without ripping it apart? I guess that is ok I am getting used to shifting in and out of OD.

 

[slag]

Originally posted by Glacier991
hmmm others are better diagnosticians than me, but I am wondering if the OD servo is stuck somehow. Not easy to get to with the exhaust sandwiching it in, but if you could I'd pop the cover and see about putting a new one in (they are cheap, about $7). other possibility is that what you sense as no OD is actually no TC lockup. THAT is controlled by a solenoid, and you can replace that without removing the trannie. I'd guess one or the other. About $30. Remember I said GUESS. Good luck.

TC lockup is controlled by solenoid and TPS. You could also check the overdrive band. When you changed the fluid, did you have any particulate in it?

Do you have a high idle?

 

[DeMo8361]

No O.D. A4LD Update

Now I'm confused....butt good

Haven't had OD since I bought the truck 2 weeks ago. After checking the fluid level, I discovered that it was full, but somewhere between pink and brown. Changed the filter and put in fresh fluid. 48 hours later, O.D. worked for about 30 miles or so then quit again. On what i thought was an unrelated note, I haven't had cruise control working at all either. During the time today that the O.D. was working, just for S & G's, I tried the cruise too. SOB.....it worked. So now, my new question is, how are the 2 related? I stopped on the way home for gas (love no O.D) and checked the fluid again, not brown, but certainly not what 24 hour old tranny fluid should look like. Plugged screen? Screen under valve body? I'm tempted to quit shavimg my head for awhile just so I could have some hair to pull out!! Oh yeah, there was some particulate, is that even a word? in the old fluid, but I have certainly seen worse. Also keep in mind I am very transmission ignorant.

Thanks Again

 

[DeMo8361]

Sorry, I forgot, idles at 900 rpm, somebody says it should idle at 700, but I have understand that the idle speed is not adjustable?

 

[Glacier991]

the screen on the solenoid I was referring to was on the 3-4 solenoid. The fact you seem to have an electrical issue (on cruise control) is also curious. Hmmm...

 

[MrShorty]

How are cruise control and 4th gear related? 1st thing that comes to mind is the vehicle speed sensor (VSS). Cruise control uses the VSS to control vehicle speed, and PCM uses VSS to know (in part) when to shift into 4th gear.

 

[fishtruck]

will the vss or tps set off a code.

i have been without OD since I put a new motor in a month ago

will be digging into problem this week

When i take off the pan, what improvements should i make...I've read about a double lipped seal but can't find part number. I've also read about tightening a bolt ?

I'm so ignorant when it comes to tranniies I would appreciate it if someone would take the time to give me a list of improvements/mods too make while i'm in there

the searches i've done although informative have also confused me so please accept my appologies for asking for info that has already been discussed

Peace

 

[DeMo8361]

and where might one find this VSS that you speak of? I have an ATSG on the way, but until it arrives, I'm still clueless......as for mods you can make to your trans, I had thought about putting in a shift kit and a better torque converter, (like I did on my Chevy 160,000 miles ago with no problems) but after all the negatives I've read about the A4LD, I think I'll just stick with using synthetic fluid and call it good.

I've also been advised when it gets corrected, whatever the correction may be, to get the biggest trans cooler I can find.

 

[DeMo8361]

Sorry for asking a question before I looked for an answer on my own. According to the Haynes manual, the VSS, (located on the trans itself) also controls the speedo reading. Is it possible that the VSS is going but not gone, or is it just this one aspect of the VSS isn't functioning right?

 

[MrShorty]

The VSS is on the end of the speedometer cable. The sensor (electronic) could be bad or any of the wiring could be bad, but the cable could still be good.
A bad VSS can set a code, but may not under all failure modes. Note that it could also be a bad wire, too.

 

[mhn3773]

Re: No O.D. A4LD Update

Originally posted by DeMo8361
Now I'm confused....butt good

Haven't had OD since I bought the truck 2 weeks ago. After checking the fluid level, I discovered that it was full, but somewhere between pink and brown. Changed the filter and put in fresh fluid. 48 hours later, O.D. worked for about 30 miles or so then quit again. On what i thought was an unrelated note, I haven't had cruise control working at all either. During the time today that the O.D. was working, just for S & G's, I tried the cruise too. SOB.....it worked. So now, my new question is, how are the 2 related? I stopped on the way home for gas (love no O.D) and checked the fluid again, not brown, but certainly not what 24 hour old tranny fluid should look like. Plugged screen? Screen under valve body? I'm tempted to quit shavimg my head for awhile just so I could have some hair to pull out!! Oh yeah, there was some particulate, is that even a word? in the old fluid, but I have certainly seen worse. Also keep in mind I am very transmission ignorant.

Thanks Again

from what i have read when u drain a tranny u dont really get all of the fluid out there is still some hiding..so u may want to run the truck for a bit then drain and fill again maybe that wil flush out more of the bad fluid

i may be wrong however..it was like that on the civic i worked on the TC held fluid in it that i wassent able to train with the drain hole

 

[Glacier991]

Let's be clear on one thing - they may seem somewhat the same, but no OD and no Torque convertor lockup are TWO different things. The apparent electrical nature of your problem is suggesting you are lacking TC lockup. If it were TRULY "NO OD" in a 91, there's nothing electrical about it. Let's for now go with no TC lockup as a provisional diagnosis.

 

[MrShorty]

...If it were TRULY "NO OD" in a 91, there's nothing electrical about it....

You'd better double check that, Glacier. Up to'87, the 3-4 shift on the A4LD was vacuum modulated like the other shifts. '88 on, the 3-4 shift, in addition to the TCC lockup, was switched over to EEC-IV control. The wiring diagram for my '92 shows TCC lockup control at pin 53 of the PCM and 3-4 shift control at pin 52.