Auto Trans Problem Help?

[Bob96]

My 97 GAGT 2.4 trans hunts around 50mph. The tach shows ~ 500 rpm changes. It feels like it is slipping in and out of TC lockup. The fluid checks ok and I have cleaned the terminals on the battery and grounds.

Also the shifter position lights aren't right. The P & R lights are right, N doesn't light, D turns on the 3 light, 2 & 1 don't work. What operates these lights? The switch on top of the trans or the computer?

Anybody have a schematic for the trans (4T60E)?

Bob

[rixGAphx]

My 97 GAGT 2.4 trans hunts around 50mph. The tach shows ~ 500 rpm changes. It feels like it is slipping in and out of TC lockup. The fluid checks ok and I have cleaned the terminals on the battery and grounds.

Also, the shifter position lights aren't right.
The P & R lights are right, N doesn't light, D turns on the 3 light, 2 & 1 don't work. What operates these lights? The switch on top of the trans or the computer?

Anybody have a schematic for the trans (4T60E)?Sorry, no schematic. That thing scares me, anyhow. :D

The lights on the console are controlled by the 'puter, which gets the data from the switch on the trans.
That switch is the Transaxle Range Sensor, and is also known as the Neutral Safety Switch. They fail from time-to-time.
$90, http://www.partsamerica.com/product_images/img/thumbs/nie/tn_ns39381-1.jpg
Here: http://www.partsamerica.com/ProductList.aspx?parttype=401&ptset=A&searchfor=Neutral+Safety%2fBackup+Switch

Good luck,
-Rick

[ENGGUY]

If the brake/light switch is not set right or ? It will disengage the TCC. Also it could be an intermittent TCC solenoid or connection to it. Or an internal leak in the transmission.
Any codes?

[Bob96]

No codes set for the transmission. I have changed the fluid and filter. Also removed and serviced both switches on the brake pedal.


Bob

[MantaGreen97]

The 96-98 cars have a problem with the valve body. I know because my car has been slowly developing the problem over the past few years.

GM switched to an aluminum valve body with aluminum valves, but they didn't realise the valves were too soft at the time. They wear/score and then fluid leaks past the bore. Commonly, the TCC lockup is affected and the car drops out of lockup during extended drives or when the trans heats up a bit.

Another common problem is that trying to a kickdown from D when pressing the accelerator to the floor, the trans will actually go into neutral (!) and you'll see the revs fly.

The solution is to have the valve body serviced, and valves (preferrably all affected ones even if you're not having problems with those it's just a matter of time) with anodised (harder) replacements. Later cars had this problem fixed but since you have a 97, like me, I'd imagine it's the original valve body in there right? There are kits that replace the TCC apply valve with a larger one that's anodised and it requires the valve body removed and reamed out, and the valve replaced. Most of these kits have replacements for all the problem areas in the valve body, so if you have that done, you should be good afterwards.

Alternately you could just replace the valve body with a revised/reman one with the problems corrected in it.

The above may or may not be your problem as you also have the lights problem. The shifter lights work via serial data from the PCM. That is, they do work off what gear the trans is selected to be in, but they don't work mechanically. So you could have either a problem with the switch as shown above, or it could be something different there.