Jimmy would not start, voltmeter read 9. After jumping battery, engine started but voltmeter did not go above 9. Battery symbol did not light up. Alternator or battery with high resistance?

it seems like the battery is going. clean battery terminals, also the grounding to the body (engine block, transmission, etc.) all should be shiny cleaned. suggest you go to autozone (or other auto parts) for a free battery & alternator tests.

I suspect a defective alternator...If you have a voltmeter, set it to read 12 volts...Read across battery terminals with engine off...Jump start vehicle and read across terminals again...Must read at least 2,8 volts higher..If not alternator is defective...If good there is a current drain on the battery when engine is off...Check for any lights remaining on...If you have a under-hood-light this is probably the fault...Remove bulb


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ill answer for NO ELECTRICAL POWER :
sure and is easy with any DMM meter, got one? any $20 DMM.
my guess;1
engine will not crank
dash lamps out.
head lights out. dead.
post systems of electrical system , all parts that work and those that dont work, and problem is easy.
cleaned battery terminals.
tried borrowed battery that reads, 12.6vdc ? (charged is 12.6)
2012 that is in warranty car.... ?
my guess on 2012
jumping a car, that is battery jump starting.
a battery can short, and no jump start on earth will start shorted battery in car. but does lay down some big sparks, or burns up cheap walmart cables.
if the car will not crank, say just that, my starter motor will not crank
jump started from live running other car.
if true then make sure headlights work , if they dont work fix that first.
HL must always work, even keys in pocket.
best is to put a fully charged battery in the car, jump starting can cause
surges that can damage sensitive electronic$$$, do jumps as a desperate measure,
with a charged battery,
1: Head lights work, no fix that , use voltmeter
2: cranks robustly.
no , wiggle shifter lever, (on A/T cars the park switch blocks cranking) On M/T the clutch blocks cranking.
with any dMM
measure battery voltage before crank and during.
12.6v good. reseted.
cranking.
0 to 10v bad (weak battery or shorted starter motor)
11 and above good. and must crank, if not , starter is bad.
to prove starter is bad, check voltage at starter solenoid coil wire lug.
it must be at 11v cranking , below 8v it chatters, and fails.
if at 0v cranking this lug that means the Key start line is failing.
A/T switch not closes, or bad ignition switch.

You need a better battery. When you hook the amp meter and read 0.3 the ECM needs to sleep

Sounds like a weak battery.
Take it out and charge it up.
Then put voltmeter across battery when trying to start.
Before starting it should read 12.5.
When starting should drop to 10.
If below 9 then either bad battery or excess starter draw.
If you stop cranking it should come back up to 12 at least.
If not, battery is not holding charge.
When it does start, must go over 12.5, and when reved, must go to at least 13.5.
If not, then alternator bad, or dirty battery terminals, engine ground, loose belt, etc.

Hello! I do not believe this is a security issue...The Battery Light is telling you that the charging system has a fault...One of three possibilities exist...# 1...The battery can no longer hold a charge...
# 2...The Alternator is defective...Or # 3...The cables that interconnect power and ground are corroded and resistive...Do you have a voltmeter and a wee bit of experience using one?...If not send a comment...Set the meter to rear +12 volts...Place the meter probes directly in the center of the battery post...Record the reading...Jump start the vehicle...Quickly remove the jump cables and while the engine is still running, take the same reading again...The second reading must be 1.8 to 2 volts higher than the first...This tests the alternator...If alternator is good...Have the battery tested...Clean cables (on both ends) if necessary...

When the battery, alternator and cables are correct, the battery light will go out...At that point in time the engine should start...If not, then we have other issues and I'll fix them if necessary...

Guru.......Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Sounds like your battery is tired and isn't holding charge as deeply as it did. As batteries get older they don't charge as deep into plates. Your reading of 12.6 is just surface reading. Have local parts store load test it -- they do it for free

The only draw above 0 should be an infinitesimal amount to hold the radio stations and any alarm requirements.
This will be easier to measure set to ammeter instead of voltmeter, because infinitesimal current can still read 12 volts. A test light also works well, because the light actually show voltage x current. An infinitesimal current will not light a test light.

But if the battery tested good, how do you know it is getting charged? Did you get get an alternator reading of 13.5 volts at the battery, when engine is revved up?

Sound like you have a bad alternator, poss bad battery too.If you can jump start it with a volt meter check voltage at battery should have above 13.5 volts, do this after you unhook jumper cables and engine running.If bad voltage reading replace alternator make sure you charge battery before starting engine with new alternator or it could damage alternator.If good voltage have battery check.Hope this helped.

For starting the engine you need :compression,petrol,ignition.