VSS on a 4L80E

[Lt.Del]

I want to take care of my intermettant shifting problem on my '91 sub since it is sunny and in the 70's and I am not going to the Richmond Sprint Cup Race tonight (decided not to work the pits tonight--my Capt, was shocked) ...might as well get this thing solved before my big ATV trip in a couple of weeks.

I know I have two Vehicle Speed Sensors--one on transfer case, one on the trans.  The one on the transfer case (I beleive is the output sensor) is obvious....
pic A


The one for the transmission is not as obvious--i narrowed the possibility down to two items...it is one or the other i hope.....

pic B

just above the shift linkage?



OR

pic C
towards the rear of the trans, near where the transfer case bolts up....




After studying the item in pic C, i noticed that the wires were stripped over the years and touching each other, this cannot be good.




So, what pic is the actual VSS?  B or C and is the trans VSS the input sensor or output sensor.    I have heard these older style (91) vss's were prone to getting dirty of trans fluid and therefore giving the computer false readings and therefore causing bad shifts.   My trans, once in a while, shifts hard b/w 1 and 2, if it ever reaches 2nd gear.   It doesnt happen often, just once in a while.

[Irish_Alley]

i cant tell from the pics but i would go to autozone or advanced and pick one up then match it up i want to say the vss in near the rear of the trany but here are some pics


Now it should look like one of those two
lmao just went to the web site to see were it was this is what i got
Vehicle Speed Sensor - Location
1991 Chevrolet Truck V1500 1/2ton Sub 4WD 5.7L TBI 8cyl
The Vehicle Speed Sensor - Location is located:
Mounted on transmission that solved the whole problem your welcome Sgt

[Lt.Del]

Yeah Irish, i went to the autozone and advance websites and still can't tell which part in the trans is the VSS withouta taking them out--which I don't want to do until i know which one is the VSS.  BTW, its a V2500 3/4 ton 4x4 but the same pics come up. 

So far, i taped up the stripped wires on the one rear thing and my tranny hasn't had a problem since. Maybe that was the problem and that particular thing is the VSS, towards the rear of the trans, near the transfer case.

Now, in preparation for my trip, I noticed my front left wheel is very, very loose--not the lugs, but the wheel bearings and I have never replaced wheel bearings in a 4x4 before.  There is a tremendous amount of play in the wheel and it is not the suspension parts or ball joints. 

[VileZambonie]

Take apart your 4wd hub and check the bearings. It's pretty easy. You will need the socket for it though.

Your wires were most likely your problem. this pic should help you out.

[VileZambonie]

Chris, can you up the image restriction size yet? Pix are too small when I post them to see detail.

[Lt.Del]

thanks Vile...those pics do indeed help.  I didn't know I had three VSS's---an input VSS on trans, an output VSS on trans and a transfer case VSS.  wow.

So far my trans has been just fine, since I wrapped those stripped wires...i dont have any idea how those wires stripped the way they did, but, glad I found it and fixed it up. So far, so good.  Those VSS puppies aren't cheap.

As for the wheel bearings, I have never seen so much play in one wheel before.  And since it is a 4x4, i have never attempted the bearings on one B4. I can do them blindfolded on a two wheel drive--the race is sometimes hard to remove, but, a buddy of mine is going to look at it for me.  I understand the subs from i think 96 on had a one-piece hub, bearing everything...the whole rotor assembly must be replaced when bearings fail and they are over $400 each.  Easy installation though, just the three or four bolts from the backside of the hub assembly...but, mine is 91 and each part is separate.  I just hope I didn't do any internal damage aside from the bearings...she was really really wobbly.  I found out by driving and when i hit a bump in the road or something, the dang steering wheel kept shaking for a couple of extra seconds...which was a sign to me that aint right.  The ball joints were replaced not long ago and I could tell when jacking it up, all the play was in the wheel--the back plate didn't go back and forth. But what was strange is that there was no noise....usually the bearings will give you an audible warning when they are going--from grinding to sqeaking--something.

 

[VileZambonie]

It's easy to service. Greasy as can be but easy to do.

You only have one vehicle speed sensor. The others are the input speed sensor (turbine speed) and the other is the transfercase speed sensor.