Hi: My daughter's 94 Sentra LE (1.6L) has both Battery and Brake Lights On. The problem started just last night. I checked the alternator and the battery - both are OK. The alternator-regulator output is 12.4V with A/C on and 12.6V with A/C off. The battery leads and terminals are very clean. The battery charge is Ok and the voltage remains >12VDC with engine turned off. Engine starting/cranking is smooth. The fuse (10A) to the Charge lamp is Ok. I'm not sure why both the Battery and Brake lights are coming on at the same time (Parking Brake released). Is it due to a defective Instrument Cluster System Bulb Check Relay (per schematic) or something else? If so, is this relay in the engine compartment or in the driver's side fuse box area? Your help will surely be appreciated.

Rod

Rod , you have a bad alternator on your hands. the lights come on when the diodes go bad inside. You should have near 14volts from your alt. when the car is running not 12.6. replace the alternator and all will be good.

jsut for kicks , u might want to pull that ebrake cover of and check for crap on the sensor. just my 2 cents

i thought u were to have 14.6 volts on the alternator and 12.6 on the battery well thats what i got out of a car today i was working on at the shop i work at maby its just that it was a ford

Thanks for your response. The problem went away a day after the original post. I'm just glad I haven't ordered an alternator yet. It's been 3 weeks now and the problem has not recurrred. The voltage at Idle-no a/c is 14 VDC and Idle-with a/c is 13 VDC.

weird. usually that's an indication that the alt is toasted. u lucked out then. what could have been the cause of that?

Ben

The alternator finally 'died' last 26 Oct' 03 and so did the replacement in less than a week. Took the car to a shop for electrical system check (short/leak) but the car tested OK. I installed the 2nd replacement alternator and it died the same day. However, I found the culprit - a portable Garmin Street Pilot III Navigation System (@ $1000). The alternator died (Brake & Battery lights came on) as soon as I turned it on during the test drive. The nav system overloads the alternator when turned on, especially in the evening with the headlights on. The nav system works fine in my Q45 and I30 which have bigger alternators. But my daughter loves this nav system so I have to find a way to make it work in the Sentra w/o killing the alternator. I'm looking at 2 options - a higher capacity alternator or a stand-alone battery to power the nav system. Anticipated problems - a bigger alternator may not fit in the tight space in the Sentra while a separate battery will require a special mounting bracket and tray in the trunk as well as regular recharging. Any suggestion?

you can get an altenator that is physically the same size but has different internals to handle the larger load but you may need to up the CCA of your battery as well to handle the additional load. where to get one I would say check around. Nissan may offer 2 different alt for your car as one would be for a car with all the options and the other would be for a base model vehicle. if you have the base model try stepping up to the options model alt.thats if this is an option. you could also see if after market parts houses offer a different alt for those who wanna put those ungodly powerful amps in their cars.

you can put in an optima which has 800 cca(red top). definitely stronger than a regulare group 35 battery. as far as the alt. goes, not too sure who makes a stronger alt of the same size. u could probably squeeze in a bigger alt off another nissan but you gotta tweak the wiring harness.

Ben