# HELP! 02 Sentra Electical/Alternator/Relay/MAS issue



## IGotThe02SentraBlues (Aug 1, 2012)

So, my 188k, 02 Sentra, 1.8 GXE has finally $h*t the bed. Or at least it seems. About 4 months ago, the left half of my dash's light went out. then I got this intermittent flashing of my brake and battery light. generally happened after the car warmed up and only when I was accelerating, which led me to believe a bad motor mount could be relieving tension on my my alternator belt... But, near the end the lights flickered, accelerating or not. So. I drove my car to and from work for awhile like this, but it got progressively worse by dimming all of my interior lights, turning my radio off completely (randomly) and fluctuating power to my headlights. Was charging my battery on my days off, and finally bought a new battery to buy some time.

So, fast forward to 2 days ago, my car was parked, idling, with the headlights on - and the airbag light starts flashing intermittently, and within a few minutes the car is dead. I get a jump, car starts, on the drive home all of the guages inside (gas, speed, tachometer) are bouncing up and down and when I finally pull of the exit for my house and to a redlight, the car dies again. My father in law brings me the new battery, we install it. Try to start the car.... NOTHING. he jumps it, I drive a mile home. As I pull into the driveway downshifting into first, the car dies mid driveway and now NOTHING works. the Car will not turn over, no interior/exterior lights, no odometer, no radio. Nothing. dead as a doornail. we try jumping it, and charging the battery, changing the terminals. nothing. the steering wheel won't lock, I can't roll up my windows.

The guys at work think it is a bad ground somewhere, or a relay (don't know where the alternator relay is located...if there is one.) But I have been reading about bad Mass Airflow Sensors, and I did have one replaced a couple years ago. (the car has a modified intake). (I did get a P0102 PD code about 2 months ago randomly, but cleared it)

I don't want to take it into my dealership, a month ago I had my oil changed there, and they stole my dipstick, and stuffed a shop towel in the tube. Bought the car in 06 at 45k, and at 55k the engine blew and they replaced it, and the clutch, and within a few months the Mass Airflow Sensor (I had the MAS replaced a 2nd time, a couple years ago - car was bucking). 2 of the times the car was brought into the dealership, they gouged my tires with the tire locks for their lifts, and when the engine was replaced they told me my new 84 month battery was dead after only driving it 10k miles. I threatened lemon laws and haven't had an issue till this last oil change. The only other issue I know of with the car is that both tail lights have been punctured and the last time I replaced the turn signal/brake light, I noticed corrosion in the female end of the light bases. 

Conclusion - I still think at 188k that the alternator is probably the issue - but what do YOU think about 'a relay (and if so, which one?), a ground, MAS'. I don't have a fortune to go replacing everything piece by piece. The car has been sitting for a full 24 hours, and acts as if no power is connected at all.

Sorry for the novel, figured the more info the better. Thanks!


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## SPEEDO (Jun 9, 2003)

next to the batt is a fuse box, have you checked them? batt cables good? tight? no corrosion etc? alternator putting out? check the grounds, make sure they are tight etc...


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## smj999smj (Jan 1, 2006)

Start with the basics! Have the battery load tested. If it fails, then have it charged and retested. If it fails the retest, replace it. Just because it's "new," doesn't mean it's good! Once you know your battery is good, make sure your cable connections are tight and clean. Make sure the alternator belt is properly tensioned. Turn the key to the "on" position and make sure your charging system warning lamp illuminates. Start your engine and check the charging system; normally you'll see around 14.7 volts, but an acceptable range is 13.2-15.0 volts. Make sure you test it at idle and at around 2500-3000 RPM and with both loads "on" and "off" (loads being headlamps, AC, etc.). If the voltage goes too high, the regulator is bad and you need to replace the alternator. If the voltage is too low, you "could" have a bad alternator, but you'll need to check the fusible link for the alternator and the circuit between it and the back of the alternator to make sure power is getting to the "BAT" terminal on the back of it. I would have suspected a bad alternator, too, back when the brake and charging system warning lights were flashing.


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## danbaz (Aug 18, 2012)

Alternator.


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