Wondering if anyone could tell me where in the dash the wires/connectors are for the VSS.

I took my car to Firestone to have the transmission service done
(long story there involving a pan gasket that decided to leak and not really having the tools/ramp/time to do the job myself)

Got the car back and out on the road and noticed I had no Spedometer and shortly thereafter the service engine soon light came on. I was like YAY more things to fix. Diag said Code 24 (VSS).

I took it back to firestone and had them try to figure it out since it was working before I left it with them.
They weren't able to find anything. The speed sensor was connected (located above the tailshaft) and didn't seem to have any shorts (or so they told me). The only place they couldn't check was back behind the dash. Which told me that hey we couldn't have messed this up and if we go any further we are going to have to charge you.

Unfortunately the shop manual briefly mentions the VSS but nothing pertaining to how to diagnose/fix it, and I can't find anything on the internet.

The firestone people said that the ECM wasn't getting the signal. so it's either a bad connection in the dash or my D*(n ECM went bad.

Any help is appreciated.

Thanks for your time.

 

If i remember correctly, they go straight back to the ECM and then display cluster. It's been i while since i worked on 1 so i may be wrong

 

I am not sure about the automatic but I would assume the sensor is located in the tailshaft housing like the manual. If they unplugged it for any reason, the contacts are very fragile. If they tried to jam it back together, they could have broken. Does your speedo have power and read "0"?

 

jerkyboy:
Yeah speedo has power and read's 0.
When I turn the key and everything is initializing you see the speedo go from 23 down to 0.
I'm thinking they must have pulled on it some how.

I'll try to prop it up tonight after work and see if I can find the sensor.

SuppaVette:
Hopefully it doesn't come down to me pulling the dash apart to get back behind the display cluster cause that would suck!

 

The sensor in the tranny sits right at the back, on the left side, and has a female connector with 2 pins inside. If you want i can post a pic of the sensor out of the tranny as i have 1 lying on my bench. Thats if your unsure of where it's located, or what it looks like. maybe they burnt the wires on the exhaust cause they didn't clip them back prop??

 

That would be awesome! I think I might know which one it is but I'm not real sure. If it's the one I think it is I'm going to need to clean it up as there is a bunch of mud/oil caked on it.

Thanks!

 

I'd also check the speed sensor itself. Last year, on my car, the rod that holds the VSS gear snapped, resulting in the same code and speedo display.

 

Well I seem to be getting resistance and such from the connector that comes from the ECM so it doesn't look like my ECM is having a problem.

Is there a special way to take out that Speed sensor to check it?
The book says to clamp it and pull it out.
I just wanna clean the contacts and such with it out of the car and not necessarily break the darn thing.

Any other troubleshooting suggestions before I pull the speed sensor out?

 

STARTING AT THE SPEEDO SENSOR AT THE TRANSMISSION CAVITY A IS A YELLOW WIRE THAT GOES TO THE ENGINE HARNESS WIRE CONNECTOR UNDER THE RIGHT DASH,THEN TO A IP CONNECTOR WHICH IS THE LARGE CONNECTOR TO THE RIGHT SIDE OF THE DISPLAY. THIS IS RUN TO D11 THE OTHER WIRE SHOULD BE A PURPLE WIRE THAT ROUTS THE SAME BUT HOOKING TO C15. THERE ARE 2 PLUGS THAT PLUG INTO THE DISPLAY, A 24 PIN AND A 32 PIN CONNECTOR. THESE CONNECTIONS ARE IN THE 32 PIN CONNECTOR. ON MY 84 I SIMPLY RAN 2 NEW WIRES DIRECTLY TO THE DISPLAY FROM THE SENSOR WHICH TOOK ABOUT 2 HOURS. HOPE THIS HELPS.

 

WOW :-)
this will be fun lol

 

Well I've finally got around to working on it again and have determined it's the speed sensor itself that has gone bad.

I'm on a parts search and found this place.
www.rockauto.com
They have 3 speed sensors I can get but not sure which one.

There is a D9A and a D9B Option code and I'm not sure which one I need.
(The third one was an ACDelco D9A) I'm going to guess and say I need the D9A?

Any help is appreciated!

Thanks

 

How do you know its bad?

I had the same problem, and it was the plastic gear on the tail shaft that had thrown the securing clip and worked its way forward on the shaft - then no mesh wit the gear on the VSS. If you take the VSS out (one bolt) the gear should be central in the hole.

If the VSS is indeed bad, the one you need will depend on your axle ratio.

 

Checked ECM voltages and those were fine.
Then got the car up on jack stands and put it in drive and checked the VSS with my multimeter to see if any voltage singles were coming from it and it had straight 0.00

I could take the VSS out but the manual doesn't say much about how.

I took the bolt out and the manual says to clamp it and pull the VSS out... well umm there isn't a whole lot of room in there and I don't think I need to be clamping it on the plastic part and breaking it. The rest of it is too wide to get anything around it.

If I do pull this thing out I will probably break it :-)

As far as the axle ratio... All I know is it is stock... where would I find the specs?

 

The RPO codes that are listed on the sheet in the compartment behind the driver seat... one of those codes will tell you what your gear ratio is...

 

You say you checked the Vss output, and got 0v. The output from the VSS is a sine wave (AC) .Was your meter on AC volts.

If you have removed the bolt and the semicircular clamp, the Vss should wiggle out of there, it is only held by the pressure of a rubber "O" ring. If it is bad, it HAS to come out. Don't take no for an answer.

As I understand it (and I could be wrong), the VSS is a toothed metal disc, which turns and induces a current in a coil of wire wrapped round a magnet. An electric guitar pickup more or less. This electrical output will vary in frequency according to how fast the toothed wheel is spinning. This frequency is then converted into a DC voltage (in the ECM I presume), so now we have the faster the rotation the greater the voltage.

The DC resistance of my VSS is 376 Ohms. So that may tell you if the pickup coil in there is good.

 

I haven't had to mess with mine so all I can offer is this http://members.shaw.ca/corvette86/Code%2024.pdf

 

I've got a speed sensor for a 700R4. It's was for my 2.59 before I went to a 3.07. I had to change sensors for the rearend swap.

Art

 

Well I think I know what was causing the problem.

When I pulled the VSS out there was a clip of some sort inside the hole that I think jammed up the gear. I Have no idea where it came from or where it goes.

I hooked the Multimeter up to the VSS and proceeded to spin it. It started returning some voltage. So I don't think the VSS is bad. I think this clip of some sort jammed the gear.

Anyone have any idea where this Clip might go or where it came from?

It looks like a little music note. If I had a camera I'd take a picture and post it somewhere.
****_
**_ |
***||
***(_) <-- My poor representation of a picture of the thing. (had to put stars in there because it was mashing the lines to the edge of the textbox.

The car runs fine, shifts great, just don't know what the heck this thing is.

 

How did you fix this?
I think this is the same problem I'm having.

Where does this securing clip go?

 

This clip has a small tang that fits in a hole in the tailshaft of the gearbox. it also slides between the plastic gear and the tailshaft to hold the gear on. Now be careful here, there are two holes in the tailshaft, and every car except the Corvette uses the front one. You need to use the rearmost hole, otherwise the plastic gears will not line up properly.

The gear is a tight fit on the tailshaft, I needed to remove the tailshaft housing, and tap the gear on using a piece of plastic waste pipe (the type used to get the water away from a kitchen sink- dunno about US plumbing though), and an improvised slide hammer to get it off (actually a 3/4" drive tommy bar from a socket set)

So the clip goes between the tailshaft and the gear.