RELAY PROBLEM PLEASE HELP.
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Senior User
Joined: Mar 2014
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No blown fuses
Cargo Master
Joined: Jun 2007
Posts: 2,723
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From: Roseburg, OR
Bottom line, relays fail. There is no deadline or lifespan on them. And hey, the relay is somewhere around $10. Go buy a new one and put it in, then tear the old one apart to see what failed.
Some of the small ice cube relays that I've worked with manufacturers say they "expect" a million operations.
These automotive relays are cheap enough that anybody should have one in their toolbax as a spare, so you might buy two.
Some of the small ice cube relays that I've worked with manufacturers say they "expect" a million operations.
These automotive relays are cheap enough that anybody should have one in their toolbax as a spare, so you might buy two.
Lead Driver
Joined: Sep 2012
Posts: 7,821
Likes: 93
From: Manteca,Ca
True story most would be a Costco battery spuing acid , then washing the battery with baking soda or even better pepsi, I would add a little dio grease and make sure all the contacts are clean.
Fleet Owner
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
302 fuel pump relay with 303 heater relay.
I would start looking at a bad fuel pump.
And a marginal over draw on current that
is not taking out a fuse can take out a relay
over time. Have a look at the fuse to see
if it is turning dark from heat.
Sean
I would start looking at a bad fuel pump.
And a marginal over draw on current that
is not taking out a fuse can take out a relay
over time. Have a look at the fuse to see
if it is turning dark from heat.
Sean
Fleet Mechanic
Joined: Jun 2006
Posts: 1,589
Likes: 20
Actually what happens, in most cases, is the relay does not fail, the contact points inside the relay become pitted or fouled. I have taken several of them apart and cleaned the contacts. Over time a black residue builds up on the contacts. If it is a high current relay, the internal contacts are normally pitted. You have two options: disassemble and clean or replace the relay. The relay that first failed on me and lead me to check the others was the "time delay" relay for the internal lights, radio, running board lights, etc.. Internal lights stayed on all the time.
Ed
Ed
Fleet Owner
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From: Spanaway
Actually what happens, in most cases, is the relay does not fail, the contact points inside the relay become pitted or fouled. I have taken several of them apart and cleaned the contacts. Over time a black residue builds up on the contacts. If it is a high current relay, the internal contacts are normally pitted. You have two options: disassemble and clean or replace the relay. The relay that first failed on me and lead me to check the others was the "time delay" relay for the internal lights, radio, running board lights, etc.. Internal lights stayed on all the time.
Ed
Ed
tossed into the trash.
Sean
Fleet Owner
Joined: Apr 2012
Posts: 27,307
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From: Spanaway
The ONLY reason I can think of is if you were stuck out in the boonies
and that was the only way to get out.
Sean
and that was the only way to get out.
Sean
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Fleet Mechanic
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Ed
Cargo Master
Joined: Jun 2007
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From: Roseburg, OR
Not trying to be a smart *** here, but do you throw away a car just because it runs out of fuel? No, you do a failure analysis to find out if it was stupidity, fuel pump, leaking fuel line, etc. That is all I did on the relays and found that I could repair them vice buying new ones or keeping them as spares or as you suggested being stuck out in the boonies. When something breaks, I basically do a failure analysis on everything, except women!
Ed
Ed
If you have a failed relay and band aid fix something, whose to say other components didn't get stressed in its failure process.
To cheap out on a relay could possibly leave you stranded on the side of the road, maybe on a vacation. Also, it could start clattering and take out a $1000 FICM or what ever its controlling. The coil could cause extra load on the system
Like I said, taking it apart just to see how it works or what exactly failed is one thing. Trying to fix one, is begging for a break down.
Lead Driver
Joined: Sep 2012
Posts: 7,821
Likes: 93
From: Manteca,Ca
Not trying to be a smart *** here, but do you throw away a car just because it runs out of fuel? No, you do a failure analysis to find out if it was stupidity, fuel pump, leaking fuel line, etc. That is all I did on the relays and found that I could repair them vice buying new ones or keeping them as spares or as you suggested being stuck out in the boonies. When something breaks, I basically do a failure analysis on everything, except women!
Ed
Ed
I don't think Sean was meaning no harm no fowl just trying to save a FTE Bud
Fleet Owner
Joined: Apr 2012
Posts: 27,307
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From: Spanaway
If you recall my background. Aviation.
You don't dress relay contacts unless you can't get a replacement
and the relay was designed for the contacts to be dressed.
Once you take a dressing file to them you remove some of the
contact and lessen it ability to transfer any heat. Heat is one of
the reasons they fail. They spark and make ozone and deposits
that increase the resistance of the contact that in turn creates heat.
Big circle.
My time is worth more than a $15 relay. They come out and go
into the trash can. If I do take one apart it's with a hammer.
To me it not worth the time or the risk to fix one. Do you think your FICM
would like fluctuating voltage from a relay that is chattering?
Sean
You don't dress relay contacts unless you can't get a replacement
and the relay was designed for the contacts to be dressed.
Once you take a dressing file to them you remove some of the
contact and lessen it ability to transfer any heat. Heat is one of
the reasons they fail. They spark and make ozone and deposits
that increase the resistance of the contact that in turn creates heat.
Big circle.
My time is worth more than a $15 relay. They come out and go
into the trash can. If I do take one apart it's with a hammer.
To me it not worth the time or the risk to fix one. Do you think your FICM
would like fluctuating voltage from a relay that is chattering?
Sean
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Senior User
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My manual says ones the blower and one is the other. I know it was the blower bcus when I switched the relays, my ac wouldn't blow anymore.
Fleet Mechanic
Joined: Aug 2012
Posts: 1,760
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If you recall my background. Aviation.
You don't dress relay contacts unless you can't get a replacement
and the relay was designed for the contacts to be dressed.
Once you take a dressing file to them you remove some of the
contact and lessen it ability to transfer any heat. Heat is one of
the reasons they fail. They spark and make ozone and deposits
that increase the resistance of the contact that in turn creates heat.
Big circle.
My time is worth more than a $15 relay. They come out and go
into the trash can. If I do take one apart it's with a hammer.
To me it not worth the time or the risk to fix one. Do you think your FICM
would like fluctuating voltage from a relay that is chattering?
Sean
You don't dress relay contacts unless you can't get a replacement
and the relay was designed for the contacts to be dressed.
Once you take a dressing file to them you remove some of the
contact and lessen it ability to transfer any heat. Heat is one of
the reasons they fail. They spark and make ozone and deposits
that increase the resistance of the contact that in turn creates heat.
Big circle.
My time is worth more than a $15 relay. They come out and go
into the trash can. If I do take one apart it's with a hammer.
To me it not worth the time or the risk to fix one. Do you think your FICM
would like fluctuating voltage from a relay that is chattering?
Sean
I was repairing a CCRM for my nephew's 1993 car. I opened it up and found a bad relay. The coil was open. I triple checked that thing twice, and I was convinced it was open. I de-soldered it and replaced it with a similar relay. After the bad relay was out and sitting on the bench I checked it just for the heck of it, don't you know it had 80 ohms across the coil. It must have been the heat form the solder iron, and messing with the pins. Now, should I trust that relay?
.
Fleet Owner
Joined: Apr 2012
Posts: 27,307
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From: Spanaway
Real true story,
I was repairing a CCRM for my nephew's 1993 car. I opened it up and found a bad relay. The coil was open. I triple checked that thing twice, and I was convinced it was open. I de-soldered it and replaced it with a similar relay. After the bad relay was out and sitting on the bench I checked it just for the heck of it, don't you know it had 80 ohms across the coil. It must have been the heat form the solder iron, and messing with the pins. Now, should I trust that relay?
.
I was repairing a CCRM for my nephew's 1993 car. I opened it up and found a bad relay. The coil was open. I triple checked that thing twice, and I was convinced it was open. I de-soldered it and replaced it with a similar relay. After the bad relay was out and sitting on the bench I checked it just for the heck of it, don't you know it had 80 ohms across the coil. It must have been the heat form the solder iron, and messing with the pins. Now, should I trust that relay?
.
It could also be in the coil it's self and will open when back under load.
When you have lived on the line and the FAA looking over your shoulder.
You don't cut corners. Would you want the mechanic that is working on
an ambulance to fix a relay and use it in a critical location like the FICM or
fuel pump only to have it fail on a run?
Sean
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