Anybody know about VSS issues?

drumsaregood46 · 05-29-2008, 05:41 PM

alrighty, here we go. 97 sl2, its been running like crap for a while and the speedo and odometer will occasionally stop working. It finally warmed up so i went under and check the VSS. The Haynes repair manual said it should have 10volts going to it for signal, according to my meter mine has 230milivolts going to it. After checking the voltage running to the VSS i put the connector back on and drove around as usual.

As of right now the problem has gotten worse. my speedo and odometer never work, my car idles either high (1500rpm) or really low (700 800 rpm). Also when i push in the clutch to come to a stop the engines rpm's drop really really low to like 400 or 500 rpm and sometimes it stalls out.

I:Ive replaced the TPS (got that code a few weeks before this started happening), ECTS (the crass tipped type) and still my car cant run like it should.

I also checked the resistance coming from the TPS and ECTS and both of the sensors are in working order.

My guess is my PCM has gone haywire. Any thoughts?

RC1488 · 05-29-2008, 07:09 PM

PCM RARELY goes bad. Its always a sensor or some sort. Clean your throttle body including all the IAC passages. Also be sure the PCV valve rattles (its the one part of the car that should rattle).

As to the VSS, im not to sure. I would check all your grounds and make sure there is no corrosion. Ssicarman may have more info onthe VSS

drumsaregood46 · 05-29-2008, 09:40 PM

PCV is clean as is the TB. when i did the TPS and IACV i took off the throttle body and cleaned it. and i got a new TB gasket too. i;m thinking its the wiring running to it maybe? i;m playing with that in my driveway right now.

At the connector for the VSS the voltage is 230 milivolts....according to Haynes it should be 10.

Right now i'm in my driveway tracing the wire from the VSS to the PCM looking for rust corrosion and all other forms of brokenness.

If anyone has any thoughts let me know.

Also if it is the PCM i;Ive heard swapping in a PCM from an automatic SC2 removes the rev limiter? true/false?

RC1488 · 05-29-2008, 10:26 PM

Quote:

Originally Posted by drumsaregood46

Also if it is the PCM i;Ive heard swapping in a PCM from an automatic SC2 removes the rev limiter? true/false?

Doesnt remove it but will increase it to 124mph. However an automatic PCM will not work with a manual tranny. Your SES light will be on and not pass inspection.

drumsaregood46 · 05-29-2008, 11:29 PM

o.k. update. According to the haynes manual the PCM has a yellow and purple wire at pins A9 and A10. HOWEVER it also mentions that the wiring schematic is only good for 1995 and older saturns. Because of this there is no purple or yellow wire going to pin A9 and A10 on my car

.

I found a yellow at pin A14 and purple wires next to it at A13 and A15. I tested the voltage and got nothing at A13 and A14 and got .5 volts at A14 and A15

seeing as i get .25 volts at the VSS connector i"m thinking i have the wrong wires.

dose anyone have a schematic of a 1997 SL2? It would be muchly appreciated!

**Ssicarman** · 05-30-2008, 01:23 AM

So far as I know the VSS does not get fed voltage. It produces an AC voltage pulse which is sent to the PCM which interprets the signals into a speed signal for the IP cluster. The Haynes manual has been known to be wrong.

I don't have schmatics for the 97 MY but the 98 shows the yellow wire from the VSS going to J3-D15 at the PCM and the purple wire going to J3-C15 at the PCM. The feed to the cluster is a dark green from D10-J6 at the PCM. Make sure of your connections at the cluster. I would tend to suspect the speedo head but you want to rule out pretty much everything else first.

If you suspect bad wires then you want to test continuity (ohm/resistance) not voltage. Do it while wiggling the wiring and the connectors.

drumsaregood46 · 05-30-2008, 04:30 AM

NEW SYMPTOM! my car gave itself a new redline of a rip roaring 4k! Its the same cut off point you hit when you rev the car when its not moving. at 4k it just slams into a rev limiter-esque thing and jerks around.

Thanks for the help Ssicarman, i will me testing what u said tomorrow.

Anyone watch that show House M.D? i feel kinda like him. bitter, pissed off and trying to diagnose some weird unknown ailment. only house is cooler and my car doesn't have lupus.

turbo_saturn85 · 08-24-2008, 05:04 AM

If the car isn't registering anything over ~5mph, you will have a fuel limiter at around 4000. I don't think you will measure 10V at the sensor connector. 10V is a odd number for the electronics. When the VSS is working, it produces a square wave at 5V peak-to-peak.

So, if you are willing to get under the car or at least hook a multimeter to the VSS wires while the connector is plugged into the VSS sensor, jack the car in the air and put it in 1st gear and let the tires spin freely in the air in 1st gear. Then watch your volt meter. You will see a voltage fluctuation and it will stay near 5V. If that step works, then your VSS is good and you need to move elsewhere.

96sc2 · 08-24-2008, 03:54 PM

My 96 sc2 has the same connections as post #6. It is inductive which means that the only time you'll see an output or voltage is if it's turning. It will be an ac voltage that you could monitor with an oscope if you had access to one. And it could be checked off the vehicle, just spinning it by hand.

The factory manual says that the resistance should be 800 to 1600 ohms on the sensor itself. That will be the coil resistance of the sensor.