is my trans going out? *update*

[solace22]

I've noticed the last few days typically in 3rd gear or above the truck starts having a problem.
At first I thought the transmission was shifting between gears or hunting gears. The rpms sound like they are changing 200-400 rpms a second like it is reving up then down then up then down literally like you were switching a lightswitch on and off.

I checked the fluids a few months ago and I'll check them again soon, they were fine no bad color or smell with the transmission fluid. The only other thing I notice is that sometimes when I first start the truck it doesn't go into reverse right away. I'll have to let it idle for a 20-30 seconds then it's fine.

The truck is on 35's, 4l60 trans, stock 350.

Any ideas?


Update. Unplugged drivers side connector. Drove really nice. Before it did not use 3rd much just for a sec then to 4th. It seemed to use all gears just fine now. None of the issue with rev up and down etc. What's the issue?

 

[4xcrazy]

Change the filter

 

[solace22]

Change the filter

Definitely going to put that on the to do list.

 

[diesel4me]

Which tranny?..

If it has a lock up converter,maybe the wiring is not making good connections and letting it lock and unlock eratically...that wont affect reverse though,thats another issue--maybe its low on fluid,filter is clogging up,some "push in" filters can come loose too and cause issues like this..

 

[solace22]

Which tranny?..

If it has a lock up converter,maybe the wiring is not making good connections and letting it lock and unlock eratically...that wont affect reverse though,thats another issue--maybe its low on fluid,filter is clogging up,some "push in" filters can come loose too and cause issues like this..

Exactly what I thought. 4l60 trans I believe.

 

[kennyw]

1990 K5 had a 700R4 stock. GM later renamed it to 4L60.

Slow to engage reverse is a sign of needing a rebuild to me.

 

[solace22]

1990 K5 had a 700R4 stock. GM later renamed it to 4L60.

Slow to engage reverse is a sign of needing a rebuild to me.

previous owners swapped around drivetrains so ill have to double check what it is. they claimed 4L60. Its only done the reverse thing once or twice. I dont drive the truck much.

 

[Greg Ducato]

The problem sounds converter clutch related, if it is the 700R4/4L60 and NOT a 4L60E then unplug it on the drivers side and see if the issue goes away. If it is a non 4L60E and has TBI then check the TPS sweep for glitch. Also check the brake switch on either trans as an out of range brake switch can make lockup come on and off just from the brake pedal bouncing as the truck goes down the road. Other problems could be leaking solenoid or pressure switch. None of these problems relate to slow reverse engagement so you are looking at symptoms for two isolated problems in all likelihood.