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Faulty odometer, airbag light, whining noise from under hood


I have a 1996 Nissan Sentra with (probably) 90,000 miles on it. It has several issues, and I will try to tell them as concisely as I can. First, I noticed that my Air Bag light came on and would not go off. None of the local mechanics would even take a look at the airbag light and the Nissan Service Center people told me that they have to replace the airbag diagnostic switch - they were not sure if it is the switch that is broken though! Then I noticed that my Odometer is not working properly (that is why I have ‘probably’ in the first line of this paragraph!) - it only moves sometimes and when it does, it moves accurately. However, I did not notice any particular pattern in its behavior. It seems to work only during some random times as if there is some kind of loose connection that snaps into place only randomly. Again, I had to take it to Nissan Service Center and they wanted to replace some kind of Odometer switch which they were not sure is broken in the first place! About the same time, I also noticed a whining noise coming from under the hood whenever I hit the brakes. This whining noise does not start immediately after I start driving though. It takes a little while (may be about a couple of miles of driving) to start and I first listen to it when I hit the brakes (like when I am at a red light). Once I hit the gas pedal, this noise is gone but then it reappears every time I stop at a red light. It remains even if I stop at a parking lot and put the car in Park. I showed it to Nissan Service Center mechanics and they were not sure what it was… And lastly, my radio stops working randomly too! The only thing I listen to is WHYY 90.9 FM on it so I don’t even fiddle with any of the controls - it is ON all the time. Often the radio starts fine when I start the car (sometimes radio won’t work when I start the car but will suddenly start working) and tends to stop randomly after a certain period of driving… for no reason. I noticed that this happens only to FM radio stations. What I mean is that when FM radio stops working I can just flip the radio to AM and it works fine.

I know there are several issues with my car. But I am most worried about the airbag light. Nissan Service Center says they need about $800 to replace the diagnostic switch which they are not even sure is faulty. With an impending DMV inspection, I am not sure how I should go about this. I wonder if the whining noise coming from under the hood is a sign of something serious to come. About the radio, I was wondering where the problem is: is it the radio that is faulty? or is it some kind of loose connection that needs to be checked? Please help!

Check your terminology I am not aware of a “diagnostic switch” I wonder why they cant plug in a Nissan scanner and read the codes in the air bag computer.

We get this refusal from independants quite a bit and airbags are not hard to work on. Sometimes repair techniques muddie things up (like having to replace entire modules for seemingly unrelated conditions) Perhaps this is what is creating the reluctance for the Indy garage to work on airbags.

I have the GM training for airbag repairs,nothing so special

Keep looking for a garage to work on your airbag. Dont settle yet for that one Dealers requirements.

You may be making a false connection between a whinning noise and brake application. When people connect some condition to brake use I always advise a wheels off brake inspection,lets get a baseline established.

Some common things under the hood that can whine are the alternator,or the power steering pump followed by the fuel in the fuel lines,maybe you are hearing the in tank pump whine,they do this worse in hot weather.

The radio sound like a simple “head unit” failure. Ask the Dealer if they have a source for refurbished OEM radios or what they do for radios that need replacement when the car is under warranty. Maybe you can use this source for your non-warranty issue.

 Your 'erratic odometer' may be a 'cluster gage' problem.  My Honda has erratic gages, but it affects all of them.  I only noticed the speedometer and odometer for the longest time.  - on and off for no apparent reason, but worse in winter.  I then found out, by running out of gas for the first time in 20 yrs. that my gas gage was also not functioning properly - the problem was it LOOKED like it was functioning.  When I filled up the gage would go to full, and gradually go down to half.  But half meant nothing, as I found.  On Hondas one has to replace the whole 'cluster' as it is one unit.  And most of my gages would start working if I drove for a while, turned off the engine, then restarted, so it was difficult to diagnose at first.  Now most of them are off, most of the time.  

 And my airbag light is always on, too, which I thought was related to the gage problem, so didn't worry.  I just happened to stumble upon this forum and found that if the airbag light is on, the airbags will probably not deploy, and was told my mechanic should be able to check the sensor for the airbag system to see if it is functional even thought the light is off - and assume they will not deploy until I have it checked for sure.

 So I am looking online for a used 'cluster gage' to have installed (helps with obeying the speed limit....), and making an appointment for my airbag system to be scanned, so I don't kill myself.