Rick, a Master certified technician, gives you tips on how to tell if its your alternator or starter is bad.

Hello everyone welcome to mechanical moments at Mercie J, I’m your host Rick Smith certified technician. One of our followers, Brandy, sent us this question. She says, "how do you know if the starter or alternator is the issue? If a 2008 Chevy suburban won’t start and the battery is OK?" Well Brandy first of all we have to define what we mean by no start because we have two types of no start.

We have the cranks but won’t start and we have the crank so it cranks, but won’t start is a situation where the car goes ni ni ni ni ni and it’s acting like if you actually ran out of fuel or something like that so we’re not gonna address that today cause I think based on your question, we’re talking about a no crank, and that means when we turn the key essentially nothing happens.

First of all, let’s talk about batteries real quick if we turn the key and we get a single audible click what I want to do is I want to make sure that we look at all the lights on the dash the lights come on when we turn the key and then when we hear that click they all go out well then that’s typically gonna be a problem with the battery cable. If you go out there under the hood, you’re gonna probably find something like if you entered Superman fortress where you have all those crystallized growth all over the place, that would be all over your battery cable. Just cleaning that up will usually resolve that. The second symptom we might have would be if we had a machine gun sound when we try to start it that’s exactly what my wife’s car did yesterday. As a matter of fact, that’s almost always going to be a weak battery. So typically we check the battery and we replace it and that’s it.

Third, when we are talking about the alternator. There’s a couple things you can do. First of all, if it’s charging, typically we’re not gonna see any lights on on the dash, everything‘s working OK. If we have a voltmeter we should see somewhere around 14 V. If the voltmeters reading at 12 V less while the engine is running then we might have a alternator issue. The other quick test we can do is turn the key on, if it has a battery light the battery light to come on and then as soon as the car starts, it should go off.

Occasionally an alternator can drain the battery and if that’s what you have, typically the car is going to work great then overnight you’re gonna get up in the morning and it’s not gonna start and then that point we could have a dome light left on. We could have anything draining the battery and we would need to check that. The starters a little more difficult. We might have that single audible click, we might not have any noise at all. If you’re savvy enough to know where the starters at you can have somebody hold the key in the start position and tap on it.

The one thing you didn’t ask about was we could also have some problems with our security system so sometimes if we get out of the car lock the door, unlock the door and reset the security system and it’ll start so sometimes the stuff can be really simple. If we have a single audible click, the lights go out or if we have the toy machine gun sound we can usually just figure that out in a parking lot.

The rest of stuff gonna be a little bit deeper and diagnostics. Always feel free to give me a call if you’re stranded somewhere and I can try to talk you through it. So thanks for the question. I hope you guys keep them coming so until next time blessings to you and safe travel.

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