How do you know when a relay has gone bad?
04-26-2005, 07:55 AM
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How do you know when a relay has gone bad?
I'm at my wit's end trying to find out why my radiator fan isn't coming on. I just had the thermoswitch replaced and that didn't do it. So I wanted to check the fan relay (in the fuse box under the hood) and how do you know if a relay has gone bad and need replacing?
04-26-2005, 02:00 PM
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I Had A 90 Accord 4dr That Would Not Turn On During Hot Weather. It Turned Out That It Was My Main Fuel Relay That Gone Bad. The Heat Made The Contact Points Expand To A Point Where There Is No Fuel Going In. I Replaced It And It Ran Perfect![quote]
04-26-2005, 02:34 PM
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My fan didn't come on like a month ago. I fooled with it for days. I even rigged it up to turn on when I turned my headlights on. We had it looked at, it was the relay. The garage said a volt meter would work, but if its something like that, they just replace it without testing. This was that "80$" fuse I was talkin about a while back, when I wouldn't let the garage touch my car.
04-27-2005, 10:21 AM
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It seems that this is pretty difficult part to acquire. A lot of automotive shops don't have it, heck some didn't even know what it was. Finally got around to Kragen and ordered one. Should get it by tomorrow. Hopefully it's what I need to get my fan up and running. 
h:
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04-27-2005, 11:01 AM
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I would assume you'd hook a sensor to it (either a voltmeter or just a simple light that lights up when it gets signal), if the relay is getting a signal from whatever is supposed to turn it on but the function isn't turning on, the relay's probably bad. You don't hear of many relays failing but I'm sure it happens.
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04-28-2005, 07:45 AM
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you can use a 9 volt battery and a multimeter to see if the relay still switches.
hook the 9 volt battery to the power prongs of the relay to activate it. using the multimeter on the control prongs (prongs other than the power side), if the relay switches open or closed then it is still functioning (an open or closed circuit depends on what kind of relay and what its function is supposed to be).
hook the 9 volt battery to the power prongs of the relay to activate it. using the multimeter on the control prongs (prongs other than the power side), if the relay switches open or closed then it is still functioning (an open or closed circuit depends on what kind of relay and what its function is supposed to be).
05-09-2005, 05:35 PM
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How to test main relay?
How exactly do you do this? There's 7 prongs on the underside and about 20 pins on the top. I have a 9 volt battery and a multi-meter and it looks like one of my pins has a bad solder joint.
03-08-2007, 05:15 AM
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I would assume you'd hook a sensor to it (either a voltmeter or just a simple light that lights up when it gets signal), if the relay is getting a signal from whatever is supposed to turn it on but the function isn't turning on, the relay's probably bad. You don't hear of many relays failing but I'm sure it happens.
