i have searched this to death.
its 1989 Camaro Iroc, 305TPi. stalling on decel & idle in drive etc.
alldata says the sensor is near the ecm i have removed the ecm and other module near it unable to located even removed the radio and dropped the panels on the left side. dropped the column, removed both kick panels. cant find this part at all. i have replaced the vss on the back of the gauge cluster problem persists, however unplugging the vss on the gauge cluster eliminates the stalling however lose 4th gear at times. i have the replacement buffer box to install but cant find the other one.
PLEASE HELP!

 

try under the dash. p.side. left of ecm. right of radio area. its a yellow box if i rem. right.

 

http://www.alldatapro.com/alldata/PRO~V239856604~C27525~R0~OB0~P5R3H~N/0/34870075/42416801/42416802/42421544/34853741/34869956/34869958/42027340/56472659/163054141/41908591
http://www.alldatapro.com/alldata/PRO~V239856604~C27525~R0~OB0~P4R0H~N/0/34870075/42416801/42416802/42421544/34853741/34857029/34857030/101367133/42465517/42064228/121071115/42457756/42250374

okay just doubled checked still see nothing in that area removed cruise module and see nothing remaining in the general area. however i have checked the wiring diagram on all data and despite it saying that the buffer box is on the right side. reviewing the wiring diagram would reveal a different story- according to the wiring diagram the vss sensor on the gauge cluster is the buffer as well? i just went and checked the wire resistance from the gauge cluster connector to ECM & cruise module (brown wire - gauge cluster c1-p8 - ECM c1-a10 - Cruise p-d) The resistance is minimal no problem there wiggled harness not value change. the proceeded to check ground wire at gauge cluster (blk/wht C1-p9) the resistance is minimal.

side note this problem has been present for years now i have replaced the ECM to additionally cure other symptoms which it did cure ei-misfire/high idle. however the stalling still persists. the current ECM is from an 87 firebird - the ECM service numbers are the same.

 

Check to see if there is a cable from the trans to the speedometer. Can check under the hood for the cable. If there is one the VSS is in the cluster. It is a small lime green box.

IIRC, the Camaro's didn't get the mag VSS in the transmission until '90. While the Firebirds got them sometime in the late 80's.

RBob.

 

When you replaced the ECM, did you swap out the Proms ? I have found the service numbers only relate to the ECM itself. The prom is more car specific ( Type of Trans, changes year to year in programming, etc). Just a thought.

 

Yes check the speedo cable from the tranny housing to the guage cluster I had that problem before and the vss has nothing to do with loosing fourth gear maybe lockup

 

Rbob - any chance of a picture of that lime green buffer ?? I only seen the yellow buffer.

 

Attached picture. Left hand buffer is the speedometer head type. The black piece toward the center of the picture is the optical pickup. It detects the reflection of a rotating bar in the cable driven speedometer. This particular unit is most likely from a Chevy van.

The right hand buffer is the 4-out buffer that is used with a 4-pole magnetic VSS in the transmission. These also come in a clear-ish white box. This particular unit came out of a Caprice taxi. The red scotch-lock is where the signal was tapped into for the meter.

RBob.

 

RBob
I have one of those lime green buffers in an engine harness I pulled out of a 90 C10.

again.

 

I did not change the prom however the stalling problem was still a problem previous i hoped that i would cure it all but cured everything but the stalling. i have replaced the yellow box on the gauge cluster (cable driven speedo). i have disassembled the cluster to see if possible wobbling or worn out bushing of some sort however that checked out. so still stumped.
Unplugging the sensor at the back of the gauge cluster stops the stalling.

 

I have spent the afternoon under the dash on both sides of the car looking for the yellow buffer box, i cant find it.
I still have no speedo, i was going to check the Yellow and Purple wires to make sure there is a signal from the VSS.
Its a 92 RS Model with the 5.0L.
All i found is a black box which is beside the ECM on the passenger side just behind the dash, it has what looks like a circuit board inside but it is sealed with a sticker. What is this box for?
can someone take a photo of the buffer box in situ so i can have another look, or is it somewhere else
Thanks

 

the vss buffer Rbob posted a pic on post #8

 

Your sig states a '92 RS 5.0L, which should be TBI. Which will have the buffer box (yellow or white).

However, you posted on the TPI board. A stock '90 - '92 TPI doesn't have a buffer box. The ECM buffers the magnetic VSS.

RBob.

 

Sorry, i saw the photo of the Yellow buffer box and got all excited.
Mine is a TBI.

 

OK, being a '92 TBI the buffer box has to be there. On the right side under the dash. Look along the ledge that holds the rear-ward side of the hush panel. May need to lie on your back and look up under the dash.

RBob.

 

HOORAY found it, mine is white and it was exactly where you said it was.
Now i can check if there is a signal to the unit and from the unit.

 

[quote=DAVID J BROWN;5596798]HOORAY found it, mine is white and it was exactly where you said it was.
Now i can check if there is a signal to the unit and from the unit. The wireing is not quite the same as the picture, but hey ho.

 

That's it. The yellow & purple wires on the right are from the VSS. One is grounded inside of the box. The other is a sine wave (AC) signal input to the box.

On the other connector, the PNK/BLK is IGN+ 12 volts, the BLK/WHT is ground.

The other three wires are digital pulses streams. DK BRN to ECM (2K PPM), the others are to the speedometer (4K PPM) and the cruise control (2K PPM).

RBob.

 

Just a fyi Billy Kay, old dead thread but 3.1L uses ecm as Vss buffer not a external box

 

I cannot find my buffer. 1989 k2500. please help!

 

It has a drac under the glove box liner.

 

I have removed that a couple times and removed the emc. I didn't see it. I'll try again. Any more tips than that?

 

try a OBS forum if you can’t find

 

Ok,now I had a 3.1 in my 92 Firebird and swapped it out for a 350. I also changed out the ECM.
How do I wire in a VSS buffer box?

 

changed ecm to what ?
might start a new thread
hers some info but depends on what ecm you have now.
https://www.thirdgen.org/forums/elec...-question.html

 

I changed the ecm to one that would work for a 350 TBI. I'm having a new chip burned for it. Since the buffer was built into the ecm I now need to know what wiring harness and buffer I need and how to wire it.

 

You went from tpi or 3.1l to tbi ?
you can use a tbi car yellow buffer box or Dakota digital sgi-100bt to correct for different rear end ratio and tire size if not stock.

 

Thank you. Would you know where I could find out how to wire it into the new system?

 

it comes with instructions