My 2002 GMC Envoy transmission slips into neutral

Q1: REVERSE IS DEAD TOO?>
no VIN told or if transmission is automatic. or manual
no engine told of 3 and tranny size matches engine power
4L60-e transmission is on 5.0L gm engine.
I think most Envoy are A/T boxes. USA, shows this .
PRNDL. Reverse. Drive and Low fail? say those words
is east,.
the transmission needs service, vast problems possible
they are complex.

causes, top:(SCAN THE PCM IS WISE SEE IF IT SEES A HUGE PROBLEM THERE.) BUT REVERSE DEAD IS A VERY BAD SIGN. SCAN THE PCM FOR SOLENOID ERRORS!

1. ATF oil leaked out of box and now dry, diP stick it? ATF smells burnt or looks like TAG is bad news. or metal flakes in the ATF DRIPPED TO A SHEET OF PAPER.
2. fuses blown but most time reverse still works.!!!
3. transmission shift linkage failed. (the service manual covers the steps to check that, Read the SM?)
4. transmission shift solenoids bad. (reverse? has none)
5. transmission is bad. (means removal time)

NOW IF REVERSE FAILS
ALL THESE THINGS HAPPEN TO ATTAIN IT.
you asked so here is a complex answer, (not all)
AND LOTS MORE TO FAIL.

http://67-72chevytrucks.com/vboard/showthread.php?t=447470

Depends on the noise. If there is a low hydraulic pressure in the transmission, it will not shift optimally. The reverse clutch pack may be worn. Sounds like time for an overhaul.

When you actuator, I assume you mean the one for the front drive splined disconnect. This would not cause transmission slippage. With your mileage, the transmission is due for an overhaul.

Perhaps it is in severe pain, because you failed to identify it it by make and model!

Sounds like the cable has shifted, from the gear lever to the transmission there is a cable that puts the transmission in the correct gear. this cable is adjustable where it bolts onto the transmission and has probably moved

Yes it has a shift cable.

I also have a 2002 Envoy. Shifting to and from 4wh and 4wa can be done on the fly but shifting to 4wL has to be done stoped and while in neutral. Try that. Otherwise I'm afraid its a new computer for you. Its located under the left rear seat and you need a loan for one.

Check ur fluid--is it burnt or have a bad smell? You might only need a trans service which is changing the fluid and filter, in the process the tech will tell u if there are any filings in the pan, if so u will need an overhaul, if not the service might fix u up--good luck

Low fluid can cause slipping. (depends upon how low) Most manufacturers post "safe" tow speeds. These are generally ignored. (not good). I recommend towing with driveshafts removed and where driveshaft has a "slip yoke" you install a yoke from a scrapyard and wire it to the tailshaft so it stays in place (keeps oil in and dirt out) Although you can't just detach the tow-bar and drive, it eliminates any possibility of trans damage, since the transmission cannot turn. (most use oil from pump to keep gearsets cool...when towing, pump is not pumping and over time and distance it can damage trans internals.)
Hope your problem is just low fluid and not a rebuild...keep in mind what I said though.

the reverse clutch has failed in the transmission, this will require the trans be torn down for repair.