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Please explain relays to me.

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Old 02-26-2007, 11:39 PM
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Default Please explain relays to me.

My car is currently half a mile away and dead in the local grocery store parking lot and it will stay there all night. I believe its because of a relay.

Yesterday, I washed the car under the hood. Just as normal, yea, it sputtered a bit after i drove it later on, but no biggy. Today, put 100+ miles on the car w/ plenty of turning off/ cranking back up w/ no problems. Tonight, i leave the gym and go get some gas and when I go to crank it up, all of the electricals are goin crazy. My guages are moving on their own, interrior lights wont come on and when they do, they're faint, and i hear a damn clicking noise in the dash. We hook up some jumper cables to a friend's car and let it charge, nothing happens. No lights or anything. I took off the cables and hit them together to make sure they worked and they did. I left the cables connected on my car and hit the other side together to make sure sparks from that side as well, it sparked. Got in the car to try again and everything lit up like it would work, turned the key and it all went dead again. Nothing. Now, it just has a clicking noise in the dash. W/ no other options, i locked the car up and left it there for the night. Man, its in a good place, but i still hope nothing happens to it tonight


Same thing pretty much happened when it had 15k miles on it. I washed under the hood and later on, the car went bizzark. Headlights were popping up and down w/out the key even in the ignition and the lights turned off. Sounds coming from the dash, lights blinking. I video taped it and took it to the local dealership and they couldnt do anything b/c by that time, the car was back working fine. They said that unless it was doing it in front of them, they couldnt do anything.

It apparently all has to do w/ relays and tomorrow, if it doesnt fire up, i guess im going to have to get it towed and fixed I hate F'n relays and I hate i cant wash under the hood of my car w/out having to worry if im screwing something up. Its not like i soaked it down, i just rinsed it off.


/rant.
Old 02-27-2007, 08:00 AM
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Relays are an electrical device that uses an electro-magnet that closes an electrical circuit, I cant remember what the numbers are off the top of my head, but if you look at the side of the relay you will see a diagram if you put a multi meterin the ohlms position or the little horseshoe looking thing to test the relay. on the diagram you will see two numbers with a little squggley line between the numbers that is your feild coilthat is the electro magnet, while testing that resistance it should be between 50 and 100 ohlms if resistance is higher replace. If the resistance is like 680olms that is a diode in the relay and should also be replaced. to test the relay switch circuit you are going to need two wires that are about a foot long each. some how connect connect one end of the wires to the battery one on each post, then hook the other two wires to the field coil on the relay this will arm the relay and you should feel it click. then take your Meter and test the remaining two terminals the relay should read .5 or less olms. this is on a late ninties GM relay please let me know if it is different. some relays have a normally closed switch but is rarely used, if this is a ford let me know and I will let you know how to test those same princible just differently aranged. I am a Ford factory trained Technician, any q's feel free. I will be on Later Tonight
Old 02-27-2007, 09:37 AM
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I am doubtful that one lonesome relay (no matter how
ill) accounts for such widespread crap. From what I've
seen on the schematics there isn't much common feed
and no "main relay".

The symptoms to me describe a power or ground fault
that depresses downstream voltage span, to the point
that relays don't work and when they do, sag the line
even more (here comes in the relay chatter).

I'd look first to battery terminals, clean / tighten, and
then chase down the BAT wire to where it becomes IGN
(keyswitch and maybe some relays) and then the ground
(sheet metal, block and BAT_GND). If you want to check
voltages do it at the battery posts while this is going on
and then move outward, BAT+ - block_gnd, BAT+ -
sheet metal, block_gnd to IGN, chassis sheet to IGN,
and so on. At some point they may show you a low
reading and then you look for what's in between the
good and the bad reading probe-points.
Old 02-27-2007, 10:05 AM
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Yeah, honestly it sounds like a bad cable connection at the battery. My son had the S10 somewhere and it had the dimming interior lights, clicking coming from the steering column and jumping didn't get it going. It turns out the car had one of those funky felt rings that is supposed to inhibit the lead salts from forming. What it did was perpetually keep the side post connection from staying secure. Any relay will act weird if the current flow to it is poor.
Old 02-27-2007, 11:50 AM
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It's possible the battery is also bad. If it has a dead cell you will never get it start even by jumping it. Check the cables first and then get a good battery. The closest these cars have to an ign relay controls only the eng sens fuse, inj a,b, a/c cruise fuses and a couple others I cannot remember but they are pcm controlled devices only.
Old 02-28-2007, 10:41 PM
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I think you got a bad battery connection or even a dead battery. Whenever i hook up my battery on the t/a, before it is completely on, it goes crazy, the headlights pop, the alarm makes weird noises and stuff clicks on and off.




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