View Full Version : For people who know cars--help please

08-23-2010, 05:14 PM
When a car won't crank, what are the first issues to check for? I know battery, but what about some others?

What are symptoms of a failing alternator?


08-23-2010, 05:52 PM
With the altenator, you'll have power to radio, windows, etc. but the car won't crank - or such has been my experience in the past.

08-23-2010, 06:04 PM
Alternatives would be starter going bad - usually car will click when you turn the key, but nothing else happens. This can also indicate a loose connection with the battery, as well, so both would be checked.

For the alternator, if the lights are running dim, interior lights running dim, radio acting flaky, power windows slow responding/working, car is hard or slow to crank, or the batt/gen light is on, its time to check it. The battery will keep running out of a charge after a few hours/days of use and needing to be jumped. If you have power but the car won't crank, its usually an issue with the battery itself, not the alternator. The battery gets the car started, the alternator keeps it going, runs the electrical stuff, and recharges the battery hold its charge.

08-23-2010, 08:06 PM
The alternator is not part of the starting circuit. The alternator is designed to recharge the battery. Trouble shooting for the alternator is how much power the alternator is putting out on a meter. If you've got good gauges, you'll have the gauge to do this on the dash. Otherwise, you have to hook it up to meter and read it. It should trigger an idiot light.

Start circuit is one of the easiest to diagnose on a car. Engine cranks slowly, lights work but poorly, and you know you've got a bad battery. Engine does nothing, lights work well, no clicking sound, but nothing else is a bad starter solenoid. Engine clicks once but doesn't turn, lights work fine, it's a bad connection or starter. Diesels complicate this with a cam position sensor, which mucks it up a bit.

Easiest thing to try first is a battery charger and see what it does. And a battery charger at Wal-Mart isn't very expensive.

Best of luck,

Jim Clark-Dawe

08-23-2010, 08:53 PM
Thanks so much

08-23-2010, 09:03 PM
If it's a diesel, you have to check both batteries. Either is very expensive to replace. Ask me how I know.


08-23-2010, 11:37 PM
As crazy as this sounds... if you have a battery that's not quite dead but too weak to start the car - turn the lights on for a minute, turn them off, then try to start it.

I know - logically, that's only going to kill the battery further - but a few years back I had a vehicle I was trying get to run so I could take it to the shop and get a new battery. When I couldn't start it, my father told me to try this trick - sure enough, it worked. Don't ask me why - I have no idea.

Linda Adams
08-24-2010, 04:03 AM
What are symptoms of a failing alternator?


Having gone through three alternators in one week ...

If you're driving, it can throw the power steering belt completely off. That happened to me a few minutes from home. Absolutely impossible to steer. All I could do was pull into a gas station and call for a tow to the shop.

It can partially throw the power steering belt off. That happened on the freeway. Steering was manageable but extremely difficult. I was able to drive twelve miles to the stop.

It can just stop working, and you might not know it. My third one stopped and the car ran off the battery. Worked fine until the battery drained, and then the radio went off first and a second later, the car shut down. All I could do was coast to the curb. (I only paid for the first alternator; the other two were rebuilt, and the shop was utterly horrified that I'd gotten two bad ones).

Other oddball things:

If the car is stick and the clutch breaks, it ain't going anywhere without a tow truck.

08-24-2010, 09:47 AM
If the car is stick and the clutch breaks, it ain't going anywhere without a tow truck.

Not entirely true, I had a clutch cable snap and its possible, if you're careful, to jam it in first to get going and then just never stop until you get home. The clutch is what makes stick gear changes smooth, you can still change without it but it's not a fun game. Admittedly the car I was driving was pretty light being a Renault something or other from the late eighties.

Other options for car won't crank - seized bearings or pistons - unlikely but requires a complete rebuild, only really occurs if the car is badly neglected or if there's an oil leak and the idiot lights are broken. Can also occur if the car has been left for a long time in bad condition/environment.

Fuses can blow too, and on some older cars (e.g. Fords) they can sometimes corrode enough to break contact and nedd a bit of cleaning before they go back in.

Lastly, there's always a small black box near the fuses that can blow and need replacing.

This is why I now buy Honda...

08-25-2010, 05:48 AM
And if you want REALLY annoying - today's cars have computers in them, and all it takes is a bad module in the computer....

(1984 Chrysler - picked it up brand new from the dealership, drove it around that night, went to work the next day. When I left work, it stalled and died in the middle of town and wouldn't restart. The wrecker came and hauled it away. I wasn't happy.)

08-25-2010, 03:57 PM
A failing alternator is usually identified by the red ignition light either staying on or flickering when the engine is running - which it will happily do off the battery for about 20 miles. It is unusual for a battery to suddenly become so flat (without warning) that it won't turn an engine, although it can happen. An alternative explanation for a dead engine is because of a problem with the starter motor solenoid. This would give a click when you try to fire up with a weak battery but remains silent otherwise. It is also possible that a lead might have become diconnected somewhere, so the message is not getting through to the starter motor.