skylinrcr01

My sister has an 05 Nissan Sentra that wont start even with a jump car. It sounds like it's trying to turn over, but it only is getting 8 volts across the battery when trying to turn it over. When its just sitting the battery is at a healthy 12 volts. Anyone know what could be wrong with it?

Thanks in advance,
-Tyler

vasquezgno

alternator??? and check the timing belt

skylinrcr01

Its got a timing chain, not a belt. How do I check the alternator without it cranking though?

ahrmike

its definitely the battery. Batteries need to be tested under load to really see if its bad or not. A "good" battery will also normally test 13.5+V at rest, and should never go below 12V under load

TestMonkey

^Auto parts store. You can rent a battery/ Alternator computer thing for free (forgot the name) to tell you which one is good or not.

skylinrcr01

Allright, Ill try that. Thanks for the help guys, this site really is an invaluable resource.

TestMonkey

NP man, Thats what we are here for

ahrmike

First off, wrong info from the others.

The timing belt jumping a tooth would NOT cause the battery to drop that far.

If anything, it could be a overly drained battery caused by an alternator, which is run by a accessory belt/serpentine belt. the belt visible to you should be tight, if thats loose then it could be preventing the alternator from charging. if the alternator is bad, it could also prevent the battery from charging.

If the timing belt skips a tooth, your car would in all likelyhood start...but idle like crap.

My suggestion:
1) Take off the battery
2) with the battery out, jump start the car (sometimes the battery will have an internal short)
---if it starts, remove the jumper cables. if it still runs, its the battery---
if it doesnt run after you remove the cables, its the charging system
Check your serpentine belt (with the engine off) for free play
if its decently tight, get your alternator checked.

Almost 100% sure those things will solve your problem. If it doesnt, we're looking at a bad fuel pump, a ECU that thinks a chipped key isnt inserted (no fuel allowed), or bad ignition coil/coilpacks.

SKYravefever

It could be the alternator, but if the car won't even start w/a jump, then that's not the first place to look. Seems like the culprits could be in what ikeyballz outlined:

bad fuel pump
a ECU that thinks a chipped key isnt inserted (no fuel allowed)
bad ignition coil/coilpacks.

ahrmike

^Sometimes a bad enough battery will short circuit the battery being used to jump your car, not allowing your car to start. If you remove YOUR battery and attempt a jump, it will start.