1996 Nissan Sentra GLE
1.6L 4cyl Auto Transmission
Mileage: 178,500
Hopefully, someone can help me with this problem. I’ve seen a similar problem on this forum with a 1996 Nissan Maxima, but my problem is slightly different.
One day while driving about 35 MPH, the speedometer dropped to zero, the odometer stopped turning, and the CEL came on. A mechanic friend checked it on his meter (P0500 code) and determined that it needed a new VSS. I replaced it, but the speedometer never moved again and the same code appeared, so I put the old VSS back in. Fortunately, I was able to take the new VSS back for a refund.
Another mechanic friend recommended that I put some silicon or vaseline on the VSS connector. I didn’t have any silicon at the time, so I put vaseline on it and it worked … temporarily. Now, it occasionally works only after the car has been recently started and is cool. Within the first few miles, it will drop to zero again. Once in awhile in those first few miles, it will jump up to the right speed, but then it drops to zero again. After the engine has warmed up, it will always stay at zero.
There is no performance problem with the cruise, automatic shifting, or anything else other than the speedometer and odometer. This makes it slightly different from the 1996 Nissan Maxima problem.
Anyone have any ideas? This is a car I bought 4 years ago for my daughter, so I want to make sure the speedometer is working. 
You need to properly replace the VSS connector on the car harness end. At that point, you may still need a new VSS sensor because its mating connector is likely to be corroded as well.
Is the CEL still coming on when the speedometer is going to zero? A lot of time the VSS sends the signel to the Power Control Module which processes and sends the signel on to the combination meter. So if the CEL is not lighting, check the connection and wiring from the PCM to the speedometer head.
Let us know what you find.
Thank you for your reply. Once the CEL comes on, it stays on unless reset. That includes whether the speedometer jumps up briefly or not.
My mechanic friend told me essentially what you said about the signal going from the VSS to the ECM and then to the meter. However, another discussion for a 1996 Nissan Maxima on this forum said that Nissans in this era sent the signal to the meter first and then to the ECM. With this bit of information, do you have any other suggestions? Thanks again for your assistance.
I’m guessing along with tardis that this just sounds like a classic poor electrical connection. Did you just stick some vaseline on it, and that’s it? Get some electronics cleaner and dialectric grease. Thoroughly clean all of the connectors, put a thin coating of grease on the mating surfaces and hook it back up.
You are right. I looked at Alldata electrical schematics and the VSS sends its signel to the combination meter. The signel then is forwarded to the ECM. Now it appears the problem could be in the wiring to the combination meter or the actual speedometer signel processing. So you might have to trace the VSS signel to the meter and see if the speedometer head is causing the fault.
I could not find a schematic for the internals of the speedometer of the Sentra. There usually is signel amplifing, shaping, and processing on the circuit board of the speedometer head but the entire part is usually changed rather than repaired. A speedometer shop might be able to troubleshoot this further.
Hope this helps.
CORRECTION: I was mistaken about there not being any effects to the cruise control. Since this is my daughter’s car, I had not been able to test drive it thoroughly. Just yesterday, I took it for a drive and tried to use the cruise control. The green light comes on when activating the cruise system, but pushing the button on the steering wheel to SET the cruise is unresponsive. The green CRUISE light on the dash does not come on either.
Maybe this will help those of you who have an understanding of the VSS, speedometer, cruise, etc. to have a better chance at diagnosing this problem. Thanks again for your assistance.
Please see the CORRECTION below and let me know if you still think I need to apply the electronics cleaner and dialectric grease. If this is still your recommendation, can these items be purchased at places like AutoZone or Advanced Auto? Thanks again for your help.
The best chance of diagnosing the VSS system is to check the complete VSS circuitry with a multimeter, using the wiring diagrams and troubleshooting charts. Search for a mechanic/electrican who can do these things, and employ him/her on the problem.
I have an '89 Cavalier that had VSS problems. Turned out the plastic (nylon ) gears were worn. Had to replace both small gear and worm gear.
You sort of ask as if this is a drastic measure. Given that this is such a simple and low cost thing to do I would do it whether it fixes the issue or not. Yes, you can purchase these things at an auto parts store - or likely even at any hardware store.