Trying to figure out why my Speedometer isn't working, pulled out the VSS and spun it by hand, and still no movement on the speedo, so thought I'd see if anyone had a known good VSS they'd sell cheap (or if close by, loan to me to try out)....

TIA

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Huck
86 Fiero GT

Does the speedo go to "0" with the key on ? If not its not getting power, ground or its bad. If it does check for continuity from the connector under the inturment cluster to the VSS connector on both wires. If there is no continuity on one or both of the wires there is a bad connection or broken wire somewhere. If there is continuity and connections are clead/good at both ends then I would suspect the VSS, although the speedo could still be bad and "0."

Which trans do you have ?

Do either odometers work? Are you getting a VSS SES light?

If the odometers work your VSS has to be working

If your ECM isn't getting a VSS signal, you should be getting a check engine light.

My 85 SE didnt have a gear on the VSS (I lost it in the trans, not fun !) drove it for 3 years with no speedo and the SES light never came on.

idk

Others do get it

quote 24 - VSS Fail Trouble Code 24 indicates that the Vehicle Speed Sensor (VSS) is reporting an abnormally low reading when other sensors indicate it should be higher. The conditions for setting this code are: No Code 33 or 34 (MAF Error) is present, and The vehicle speed signal indicates < 4 MPH and Engine speed is between 1400 and 4400 RPM, and During a low load condition (LV8 between 50 and 99), and Transmission not in Park or Neutral, and All conditions met for more than 20 seconds If the code was logged when the vehicle was in motion, the following should be checked: Defective or corroded VSS connections Misadjusted TPS sensor. The TPS should read about 0.42 volts at closed throttle Defective speedometer cable Bad or missing speedo drive gear(s) in tail shaft housing of the transmission Defective VSS Defective ECM

Sorry, I should have given my cars specs in the first post....

It's in an 86 GT with the stock automatic transmission.
The needle sets on Zero, never moves,
Odometer and trip do not work.
Cruise Control does not work
No CEL,

All other gauges work fine...well, the Fuel gauge is pretty flakey, but the oil, temp, Amp, and Tach all work fine.

Scan ECM... ECM should tell you if ECM getting a signal from VSS.

test
Check ac volt at VSS when VSS turns. Any voltage likely means VSS works.
then check ac volt at pins R, PPL/WHT wire, and G, Yellow wire, on C203 next to ECM.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Good info I'm sure.....but something I didn't mention, while I'm pretty good with a wrench, I HATE wiring, so checking voltage at pins is not exactly something I'm comfortable in doing....but if the weather lets up some, I'll give it a go (Was 1 degree this morning...buurrrrrrr)

If you have a variable speed drill, remove the gear from the VSS and insert the VSS into the drill. Lock it on at the lowest speed, turn on the ignition and you can check the circuit for breaks and bad connections.

On the second VSS - the one you have out of the car. Take your volt meter and set it to dc volts - stick one probe into each side of the connector making sure the metal of the proble of your meter touches the metal of the connector. One in each. Now spin your VSS gear and watch the volt meter. It should go up to like 250 mV and down to like -250 mV. It won't be consistant since you can't spin it consistantly. You should see both + and - voltages. So stick it in, spin it a couple of times watching the meter and you will know if your VSS is working.

It is currently in the car, I pulled it out this past weekend and turned it by hand to see if the speedo would move (it didn't) but re-installed it as I had to drive it back home (Had it up on a rack).

I'll try hooking it up to a meter the next time I have a chance, gotta warm up some first...just trying to have the info when I get the chance to check into it some more.

This is definitely a great forum, I appreciate not getting grief over what is probably simple stuff to some members...
With me just getting back into Fiero's I've got some catching up to do

OK - yeah I misread and thought you already had two.
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quote I appreciate not getting grief over what is probably simple stuff to some members... With me just getting back into Fiero's I've got some catching up to do

I can try to be more of an a-hole.

[This message has been edited by phonedawgz (edited 12-15-2010).]

Until I get this fixed can someone give me approximates on what MPH it is running at what RPM? (86 GT w/TH125)
Thanks!

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Huck
86 Fiero GT

Just got around to testing the VSS as shown in the above video, and the VSS does throw readings on my meter, so I'm gussing it is good, so either the wiring is bad somewhere, or the speedometer is bad...
The Speedometer needle never moves off 0 mph, the trip and Odometer never move either....so does this sound more like a bad wire, or bad speedo?
Or I suppose it could be the gear inside the transmission, but I'm hopping not, as I doubt that is an "Easy fix"..

Any more thoughts?

Plus an Approximate MPH it is running at what RPM would be helpful, until it is fixed...

Thanks in advance!

According to the service manual, the VSS must produce a 60HZ AC signal to create a 54MPH reading on the gauge. This doesn't necesarily mean that if you turn the VSS at 60 RPM you'll get 54 MPH though. Much depends on how many poles there are to the magnet inside the VSS, which I don't know.

The thing is, I don't think you need to worry about the VSS since you've proven it works already. You should concentrate on the connections at the speedometer. It's the 18 pin connector that mounts vertically to the bottom of the instrument pod. The pins are numbered A through U. Do these tests to narrow down the cause:

1. Unplug the connector and using your mulitmeter set to VDC, turn your ign to RUN, engine off, and test pin T (yellow wire) for 12V.

a. If you don't get 12V, then check your RADIO Fuse;
b. If you do get 12V, then the power supply is OK, so turn the ignition OFF, then;

2. Set your multimeter to ohms and test for end-to-end continuity between speedo connector pin R (ppl wire) and the unplugged VSS connector pin B;

a. If you get infinite ohms, then your ppl wire is broken or not making good contact at C203 under the armrest;
b. If you get zero ohms, then test one end of ppl wire to ground;

i. If you get zero ohms, then your ppl wire has chafed through the insulation somewhere between the speedo and the VSS;
ii. If you get infinite ohms, then the wire is OK, so;

3. Test for end-to-end continuity between speedo connector pin S (yel wire) and the unplugged VSS connector pin A following the same procedures for 2. above;

4. Test for end-to-end continuity between speedo connector pin D (blk/wht wire) and a known good ground;

a. If you get infinite ohms, then the blk/wht wire is broken somewhere between the speedo and G504 which is a large eylet bolted to the forward cylinder head with a blk/wht and a blk wire pair, under the exhaust Y-pipe. (Not to be confused with a second large eyelet with a green and tan wire pair). This is a common problem area where the wires break because of the heat;

b. If you get zero ohms, then the ground wire is OK.

Once you've done these tests, if you still can't find a problem, then the problem is likely the speedo circuit card. Post what you find. Good luck.

OK, FINALLY got around to working a little more on this...
Responese below in Bold

quote Originally posted by Bloozberry: According to the service manual, the VSS must produce a 60HZ AC signal to create a 54MPH reading on the gauge. This doesn't necesarily mean that if you turn the VSS at 60 RPM you'll get 54 MPH though. Much depends on how many poles there are to the magnet inside the VSS, which I don't know. The thing is, I don't think you need to worry about the VSS since you've proven it works already. You should concentrate on the connections at the speedometer. It's the 18 pin connector that mounts vertically to the bottom of the instrument pod. The pins are numbered A through U. Do these tests to narrow down the cause: 1. Unplug the connector and using your mulitmeter set to VDC, turn your ign to RUN, engine off, and test pin T (yellow wire) for 12V. a. If you don't get 12V, then check your RADIO Fuse; b. If you do get 12V, then the power supply is OK, so turn the ignition OFF, then;. Got 12 Volts 2. Set your multimeter to ohms and test for end-to-end continuity between speedo connector pin R (ppl wire) and the unplugged VSS connector pin B; a. If you get infinite ohms, then your ppl wire is broken or not making good contact at C203 under the armrest; b. If you get zero ohms, then test one end of ppl wire to ground; i. If you get zero ohms, then your ppl wire has chafed through the insulation somewhere between the speedo and the VSS; ii. If you get infinite ohms, then the wire is OK, so; Ohmed out good 3. Test for end-to-end continuity between speedo connector pin S (yel wire) and the unplugged VSS connector pin A following the same procedures for 2. above; Ohmed out good 4. Test for end-to-end continuity between speedo connector pin D (blk/wht wire) and a known good ground; a. If you get infinite ohms, then the blk/wht wire is broken somewhere between the speedo and G504 which is a large eylet bolted to the forward cylinder head with a blk/wht and a blk wire pair, under the exhaust Y-pipe. (Not to be confused with a second large eyelet with a green and tan wire pair). This is a common problem area where the wires break because of the heat; b. If you get zero ohms, then the ground wire is OK. It gets strange here.....there is no wire in the "D" Slot, the only blk/wht wire is in the "P" Slot, and it Ohms out to a good ground...so "shold the blk/wht wire be in the "D" position?...there is a "Prong" in the "D" slot, but no wire attached to it.. All the others were as you stated they would be. If "P" is where it is supposed to be, and it tested right, this means that it has to be the speed-O itself, Correct? Once you've done these tests, if you still can't find a problem, then the problem is likely the speedo circuit card. Post what you find. Good luck.

[This message has been edited by Huck369 (edited 01-30-2011).]

I have now pulled the speedometer, and found some corrosion on one of the screws holing the board, and a little corrosion on the board, cleaned it up, and reinstalled it, but still not working....so I guess I'm in the market for a good 120 Speedometer...

New Speedometer fixed it!!
Still no Cruise, but at least now i can tell how fast I'm going!

Thanks for the help!