Ignition hesitation?
#1
06-02-2010 | 10:28 PM
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From: Mesquite, TX
Ignition hesitation?
Hey guys. Within about the past week I've begun to notice that when I hop in the truck and go to start it, it seems to hesitate for a second or two before cranking up. Cranks fine, runs like normal. It's just after I turn the key it waits a full second or so before turning the starter. No odd noises or anything. Anyone experienced this before? Wondering if the switch/solenoid is getting worn out. TIA.
#7
06-03-2010 | 03:58 PM
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Joined: Apr 2010
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From: Meeker, CO
The easy way to spot a tired relay whose case is opaque is to listen while energizing it -- there will be a relatively long latent period between application of coil voltage and the click of the contacts closing. If the relay is too quiet to be heard over ambient noise, you'll have to test it electrically. A multimeter or test light will work just fine in an automotive application. The tricky part is finding the right wire to probe.
All that said, the easy way to figure it out is to swap in another (known good) like relay from a non-critical circuit and see if the problem clears up. If it does, you need a new relay.
Last edited by UnregisteredUser; 06-03-2010 at 04:00 PM.
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#8
06-03-2010 | 04:06 PM
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Joined: May 2005
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What happens is that the core of a DC relay eventually gets magnetized so it is not so greatly affected by the magnetic field created by the relay coil. The symptoms are reduced contact pressure and slow closure. Later, the contacts just won't close at all because the core can't overcome the contact spring pressure. Depending upon the relay style, you may or may not be able to detect a magnetized core by measuring the coil current. In those relays that don't have (current) limiting resistors or solid state drivers in them, coil current will go up in proportion to the magnetization of the coil. To test in this way you need to know what a normal relay's coil current should be.
The easy way to spot a tired relay whose case is opaque is to listen while energizing it -- there will be a relatively long latent period between application of coil voltage and the click of the contacts closing. If the relay is too quiet to be heard over ambient noise, you'll have to test it electrically. A multimeter or test light will work just fine in an automotive application. The tricky part is finding the right wire to probe.
All that said, the easy way to figure it out is to swap in another (known good) like relay from a non-critical circuit and see if the problem clears up. If it does, you need a new relay.
The easy way to spot a tired relay whose case is opaque is to listen while energizing it -- there will be a relatively long latent period between application of coil voltage and the click of the contacts closing. If the relay is too quiet to be heard over ambient noise, you'll have to test it electrically. A multimeter or test light will work just fine in an automotive application. The tricky part is finding the right wire to probe.
All that said, the easy way to figure it out is to swap in another (known good) like relay from a non-critical circuit and see if the problem clears up. If it does, you need a new relay.
Awesome explanation. I done learnt something today.
#9
06-03-2010 | 04:24 PM
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From: Mesquite, TX
Well, I just went out and swapped the relays. No change. It seems like the delay is somewhere between the relay and the starter. Relay clicks-1 to 2 second pause-Cranks. I'm starting to think the starter's just getting worn out due to a seemingly slow crank..
EDIT
Now it's only wanting to start every few tries. Nothing but a click otherwise. New starter and cables, here I come..
EDIT
Now it's only wanting to start every few tries. Nothing but a click otherwise. New starter and cables, here I come..
Last edited by J McWillis; 06-03-2010 at 04:36 PM.
