starter "buzzing" sound - what causes it?

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PattiM
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starter "buzzing" sound - what causes it?

Postby PattiM » Mon Mar 04, 2019 10:13 pm

I have a 1992 Pathfinder 4x4 6 cylinder.

Sometimes the starter won't crank, instead there's a sort of a buzzing sound, sort of like a relay not closing or poor electrical contact, which sounds like it's coming from under the passenger side dashboard or else on the firewall in the engine compartment on the starter side. After a couple of tries, it doesn't buzz but just starts cranking normally. It seems more pronounced in cold weather.

I changed the starter relay and the starter motor assembly - but I still get the buzz some of the time. I cleaned battery connections and the new starter's connections are tight. So I am thinking, what other relay might be making this noise? There was a note in the new starter's box that there may be something called an "inhibitor relay" in addition to the starter relay - but I can't find any documentation of this. I have the Chilton's and the Haynes' but I couldn't fine any mention of either of these relays.

EZ Starter Change on 4WD vehicles:
https://www.youtube.com/watch?v=Pn9TeW9hUtE

Does anyone have any ideas? Thank you very much! I'm trying to avoid being stranded...
Last edited by PattiM on Wed Jun 19, 2019 2:23 pm, edited 1 time in total.


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smj999smj
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Postby smj999smj » Tue Mar 05, 2019 5:21 am

Any chance you have a few stripped teeth on the flywheel and what you're hearing is the starter's Bendix drive free-spinning when you try to start?

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Postby PattiM » Tue Mar 05, 2019 9:29 pm

smj999smj wrote:Any chance you have a few stripped teeth on the flywheel and what you're hearing is the starter's Bendix drive free-spinning when you try to start?
Thanks for the reply. No, it's a relay buzz or something - nothing hard like gear-clash. And the starter doesn't activate. At least I'm pretty sure of all this. I've had cars with stripped teeth before or a solenoid that didn't fully extend the starter gear... a really harsh grinding.

Does anyone know where the Inhibitor Relay is on a 1992 4x4? (6 cylinder) It isn't any of those I can see on the wheel wells or in the relay box...

Thank You!

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smj999smj
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Postby smj999smj » Wed Mar 06, 2019 9:06 am

They are usually in the engine compartment on the passenger side. Exactly which one I couldn't tell you without looking it up in the factory service manual. If you want, you may be able to find a free, downloadable manual at NICO Club's site. Low voltage can cause relays to "buzz," so you may want to check your battery cable connections and battery.

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Postby PattiM » Wed Mar 06, 2019 7:53 pm

smj999smj wrote:They are usually in the engine compartment on the passenger side. Exactly which one I couldn't tell you without looking it up in the factory service manual. If you want, you may be able to find a free, downloadable manual at NICO Club's site. Low voltage can cause relays to "buzz," so you may want to check your battery cable connections and battery.
I'm guessing mine doesn't have an inhibitor relay. Can't find it anywhere. But a friend tried starting the car, and the buzzing is coming from the starter relay. It only happens every now and then. The car starts strongly.

By the way - there are a couple of empty connectors by the starter relay. I assume they're test connectors since everything runs find and they're quite dirty (and so have been empty for a long time). They're not next to any mounting points - just short leads coming from the harness.

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Postby smj999smj » Wed Mar 06, 2019 11:12 pm

There are no test connectors under the hood. Those are relays for other options that your vehicle doesn't have.

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Postby PattiM » Thu Mar 07, 2019 12:48 pm

smj999smj wrote:There are no test connectors under the hood. Those are relays for other options that your vehicle doesn't have.
AH, thanks. Cool!! I had a friend try starting the engine and the Starter Relay buzzes in my hand. Why? Battery voltage is perfect and all connections are tight and clean. Weird!

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Postby smj999smj » Thu Mar 07, 2019 3:38 pm

Could be the relay is starting to fail. If you have another similar relay on the vehicle, swap them and see what happens.

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Postby PattiM » Mon Mar 18, 2019 6:59 pm

OK - so I know it's the starter relay (even though I've replaced it twice in the last few weeks). I put my fingers on it as I turn the key at a time when the car is "buzzing" rather than starting, then I can feel it buzz. SO, what would make the buzz happen instead of the starter just cranking? All terminals are clean. And 9 out of 10 times, it will just start normally with no buzz, but 1 out of 10 times it will just buzz. I turn the key off and back to start and it may buzz once or a few times, then suddenly start perfectly.

The ONLY thing I can think of is that the starter switch on the steering column isn't sending enough voltage to the relay? What else could it be? I think there's another relay-ish sort of thing somewhere (which handles the BIG currents for the starter) - is that correct? (The starter relay doesn't have big enough wires going to it to be switching the huge currents the starter draws...)

Any ideas anyone? Help! I don't want to get stranded...

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Postby smj999smj » Tue Mar 19, 2019 12:47 pm

You could remove the relay and put a 12v test light in the terminal for the ignition switch input while someone turns the key to start and see what happens (dim light, flickering, etc.). I would be inclined to suspect a poor ground on the circuit. Get the wiring diagram for the starter circuit, locate the grounds and clean them up.

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Postby PattiM » Tue Mar 19, 2019 5:45 pm

smj999smj wrote:You could remove the relay and put a 12v test light in the terminal for the ignition switch input while someone turns the key to start and see what happens (dim light, flickering, etc.). I would be inclined to suspect a poor ground on the circuit. Get the wiring diagram for the starter circuit, locate the grounds and clean them up.
Wow, thanks - good idea. That's called a "12v test light?" I see these on amazon - but the look like they're meant to connect between "+" and a chassis ground. To test, do I hook it across pairs of terminals in the relay socket (after removing the relay) or between ground and pins in the socket terminal?

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Postby smj999smj » Tue Mar 19, 2019 9:36 pm

Clip the alligator clip onto a good chassis ground or the negative battery cable end or terminal and the pointed end to the power terminal in the harness connector.

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Postby PattiM » Fri Mar 22, 2019 9:00 pm

smj999smj wrote:Clip the alligator clip onto a good chassis ground or the negative battery cable end or terminal and the pointed end to the power terminal in the harness connector.
Thank you very much. Is there a "computer" on this age of car that can tell anything on this?

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Postby smj999smj » Sat Mar 23, 2019 7:03 pm

The ECM has self diagnostics but it's crude compare to today's OBD II systems. I can't see where it could give you any information regarding your particular issue.

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fix?

Postby PattiM » Wed Mar 27, 2019 8:21 pm

OK, I found a video online with the exact same buzzing I'm hearing from the starter relay. (but on a honda accord) The sound is at about 3:25 into the video.
https://www.youtube.com/watch?v=5zZZWd--duE

I haven't replaced the starter switch yet. I'll post the results.

EDIT: Guess what? It was the starter switch!! But I guess I got a new starter (rebuilt) and a new ignition relay and clean electrical terminals out of the deal. Ugh!! It's a fair amount of effort to get the starter out of a 4x4 of that type.


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