Greetings....
Mike here with a sad 92 V-6 700R4( 88K miles ) that was abused by it's previous owner... the good news is I got it for $175.00.... Now it runs & drives!( after fixing the VATS system & putting the steering column back in one piece!)

This is the start of a father son project.. and will be my younger son's 1 st ride! I will not get into the horrid abuse the car had withstood during it previous ownership.. suffice it to say.. it's got a good home now!

Here's the current problem were facing.. the speedo nor odometer do not work!
I have replaced the VSS sender to no avail....The Actron scanner doesnt see speed pulses...But there are currently no error codes.. (but I havent driven the car recently short of moving it in & out of the garage...

Here are the questions

1) Where can I score a GM shop manual ( none on E bay currently) ...Im an electronics engineer.. and with just a little help I might be able to brain this out.. but this is my first Camaro ( cept for my 1 st car a 67 327 Camaro) that has the more complex ( read over thought ... under built) speedo system.

2)
A] What are the proper color wires that should go to the 2 pin speedo sensor.. there has been some "mods" done to the car .. and I trust NOTHING that I have not fixed & proven myself.. (sounds paranoid.. you havent had to remove 7 feet of house wiring to bypass the fan).
B] What is the path that the wiring goes from point A ( the tranny ) to point B the ECM ( or maybe the speedo first?).

3) does the VSS signal SPLIT to ECM & the speedo cluster?
I have removed the "orig" cluster.. and substuited another one... that yeilded the same results..NADA.

4) Is it POSSIBLE that the output shaft gear that drives this VSS sender in the tranny has moved or is broken... I didn't inspect that as well as I should have.... after my ATF bath when popping the sender out..DUH!


Thanks
Mike

 

Hi ya, Mike!

I believe that the VSS sends the signal to both the ECM and the speedometer. The Odometer is sourced from the speedometer, which is why it doesnt work, either.

The transmission uses two wires, (Dont have the color handy) that are tied to a magnetic field effect transducer. I agree that before you pursue the signal any more on the inside of the car, that you should test out that sender in the transmission and continuity check the wires to the VSS.

The wires are yellow and purple: Check them from the transmission connector to the VSS. If they are OK, then check the VSS for power which is a pink/black wire. If you have power, check the green/black striped wire (It might simply be green) and check that it runs to the speedometer. It is the 4000 pulse per mile signal, which IIRC, is the proper pulse count for a '92 vintage speedometer.

 

Would it be possible to unplug the sensor, put a test device on it like a meter and go for a ride to see if it is producing output?

 

That's the plan later this week ( when I can find the wiring going to the interior)

I did take the old sender and spun it up with a cordless drill and it was VERY intermittant.. So I will do more research tonight on the bench ( speed vs output ) what I really need is a shop manual to expedite my understanding of the circut.

Thanks'
Mike

 

Vigman,
The sensor outputs a low-voltage sinusoidal waveform and the VSS converts it to a 2000 pulse per mile and a 4000 pulse per mile square waveform, probably TTL.

 

That's what I had concluded.. but need more help here... like a scan of a shop manual.I did find one but it's a week away, and this is making me very angry ( to quote Marvin )... So can anyone state the pins/ connector where the speedo sensor shows up on... ? I need to find that point first...

Thanks
Mike

 

Ok here was the deal.... the speedo gear was stripped or WRONG... the one I pulled out was a brown 39 tooth gear.. what I have in now is a 42 tooth ( 10.00 at GMC) and it's yellow. I tried a new ECM, A new speedo, a new VSS sender ( BTW in a 92 you do not have a seperate VSS buffer box under the dash to make the split to the cruise control.. that is now an ECM function).. so how did I find it.....

First I got the shop manual.. and that wasn't 100% clear... next I got a battery operated audio oscilator and injected a 120hz ( 1 volt AC ) signal on the yellow & purple pair down by the VSS and bingo my speedo jumped to life.. as frequency went up so did the speedo... and the ODO & trip indicator spun as well

Next I took the car, Jacked it up pulled the VSS sender ( AFTER TAKING AN ATF BATH!).. re connected the wiring and used a makita drill motor to spin the sender up... that worked

Next I tore apart the OLD sender so I would have a shaft in the housing so the gear could line up & turn by spinning the drive shaft... and it did... however with the silghtest perssure on the VSS shaft the gear would no longer turn and I head a tic-tic-tic.

So the gear for the VSS was worn to it would not mesh properly.

Off to GM I went and bingo the new gear fixed the "issue" and since I had to have the car smogged.. I checked the accuracy and it was right on ( fearing I had the WRONG GEAR ( 42 vs 39 ). BTW the car passed smog with Flying colors.

So all I can conclude ( based on the amount of MODS the car had) that for some reason.. the guy was in there before & put the wrong parts in.

So I hope this saves somebody some time & money.

Anyone need a 49 state perfect stock ECM?

Vig~

 

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