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07-21-2020, 01:27 AM | #1 |
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Dead Short = Dead ride till figured out!
I tried to locate this situ in the threads, to no avail.
-The problem, I blow the fuse as soon as battery terminal is first hooked up. -Simple check- led me to need to disconnect the +positive cable from the top of the alternator so I could connect the battery terminals without (as far as I see is) a dead short. Story- I had to park the subie so I could remove the central exhaust section to weld up a leak. This weld work was done off the car. I don't know if welding on the car with everything hooked up, would damage the circuitry or battery. (would that hurt anything? I haven't seen trouble with my classic cars before) unexpected life stuff and I had to leave the subie parked for maybe 3 months. I guess the last month when I lapsed on checking on it and the battery was completely dead. Bought a new standard replacement. My first time touching the battery terminals, the 80 amp Main Fuse Blew instantly. Actually it was already replaced with a 100 amp fuse, so at least it blew being allowed to over Amp by 20 more Amps without frying something else. Back to my Simple Check above. When I removed the +Positive post of the alternator with or without the 3 wire plugged in, was the only way to Not Short Circuit. The strange thing that never happened to me any other time working on this when hooking up the battery cable after a while... Car seemed possessed! The ABS (?) Brake Pump in front right corner, and some other small motor sound that came from up front kept running. Oh and the Interior air vents from the dash, but the knobs were all turned off! I used a 20 amp fuse to do that test just in case the car tried to turn a wire into a light bulb. I already pulled the fuse block from its mount, but it's so tight I could not see any issue underneath. I am used to building classic cars from head to toe, this is the first car I have had that has a brain... and that needs to Smog, ick! I need to figure this out, Anyone have any ideas??? Much appreciated, EP
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07-21-2020, 10:33 AM | #2 |
Trust no one
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Was it parked in a place where small rodents might have access to it and be nibbling on the wiring? This is a common occurrence when vehicles sit around for long periods.
If the main fuse is spec'd at 80A, that is what should be in there. Never replace a fuse with one rated for a higher current. |
07-21-2020, 05:24 PM | #3 |
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Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:2001 LL Bean Outback Winestone |
If I understand your post correctly you stated that if you remove the main output lead of the alternator the short problem is cleared. If that is correct then you need to replace the alternator. It most likely has shorted diodes inside it.
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07-23-2020, 02:01 PM | #4 | |
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Quote:
-Alternator - was Tested, and said to Function Fine. I have a receipt from that Test Bench showing the values, I can provide them here if you think it will show something. -Regarding removing the Positive (+) Terminal, to stop the Short Circuit - I placed a 20amp Breaker, that has a Fast rate to trip it, in place of the 80amp Main Fuse and sucker blows aggressively. I have a guy at our shop that is real good with electronics, High voltage industrial like in commercial use, But he is also real good with DC low voltage. It has us stumped as to why the battery was Dead as in a trickle low amp drain, but upon allowing it 20 amps (that Temporary breaker) it blows as soon as it touches. (asking myself)-Why didn't it blow the 80amp in the first place while it sat?! -The Rodent issue - happened to me on another vehicle. I didn't see anything yet. I am right at the point of pulling that part of the Wire Loom out/apart to see if it is grounding out. I will also check if there is a sharp edge that rubbed through the insulation. My Subie is parked in the back of our shop out in the open, on asphalt, without food sources common to high Rat/rodent population. We are a Fabrication shop building Props for the Movie's and more. I have rat traps out all the time, but catch one maybe every month. Though, I know it only takes one to mess up our rides! -The Main Fuse being Oversized - Yes, I agree that No fuse should be larger than appropriate, so as not to cause a meltdown. I have a new 80 amp Circuit breaker (correct size, but with ability to reset) to go in after the situation is fixed. I purchased the Subaru Manual from somebody on ebay in CD form. It covers my 2005 STI and a few other years, but by God there are thousands of pages!!! It is hard to go through since there are no links to take me to the right chapters. I am going to rip on the harness this weekend. My fear is I'll have to take it to a mechanic, and I don't have much in funds due to COVID shutdown of my work for 4 months. :-( Last edited by Wayfarer9; 07-23-2020 at 02:24 PM. Reason: Forgot some info. I'm responding to 2 posts as well :-) |
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07-24-2020, 02:05 PM | #5 | |
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Vehicle:2001 LL Bean Outback Winestone |
Quote:
The wiring section of the factory manual is logically layed out. The power section will tell you where all the fuses tie to. Last edited by Cougar4; 07-24-2020 at 02:41 PM. |
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07-27-2020, 01:39 PM | #6 |
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To Cougar4 - Thanks, that's a good point. Thankfully I didn't rip into the harness yet, got busy helping family out. There are many of us, it's a big Irish family!
I should be able to check on it in these next couple days. Multi-meter is juiced up and ready to go. I'll report back |
07-27-2020, 11:02 PM | #7 |
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Alternator Test Results - I couldn't locate my nice Multi-meter, but I had a cheap backup here so I just used it for now.
Multimeter set to 20k ohms = 16.2 from (+) terminal to Housing, but when set to 2000 ohms it would blink with a random number each time and then show as if I touched nothing. When testing leads together the numbers would drop to 002 I can't access anything through the backside, but I could tear the Alt open. There is only a removable terminal extender to make it easy to access mounting while in the car, but that was in good condition. I keep hoping for an "Ahaa" moment. PepBoys Test Bench Results - Rectifier, Regulator, and General Test = Passed B+ Voltage = 14.97 Ripple Voltage = 0.34 Lamp On Voltage = 1.13 Lamp Off Voltage = 14.64 Part #11058. Would pictures, or part numbers help? |
07-28-2020, 11:34 AM | #8 |
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The resistance test you did shows that there isn't a short to ground on the stud. When you changed the multiplier to 2000, the meter was just showing that the resistance you were measuring was beyond what it could measure using that scale. You were better off using the 20k scale.
From what you have stated about the problem so far it seems my idea about the shorted stud was possibly correct. Now that you have proved there is no longer a short on the stud go ahead and touch the battery lead to it, nothing bad will happen. When you place the output lead on the alternator along with the nut I suggest you remove the positive battery connection before doing that. After you have carefully tightened the nut then check the resistance of the stud to ground again to make sure the short hasn't returned. If you have no short then put the positive battery post on the battery and lightly tighten the connector to the battery post. Then get back to driving. Last edited by Cougar4; 07-28-2020 at 07:05 PM. |
07-29-2020, 12:51 PM | #9 |
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Wiring is an incredible pain in the ass to diagnose and is usually not worth fixing unless you have a spare harness to drop in.
I'm having a similar issue with my swapped GC. Body wiring is fine just ecu harness is completely dead, and it's not even blowing fuses. Thinking of just selling the turd as-is and buying something more reliable. |
07-29-2020, 07:31 PM | #10 | |
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Quote:
Fuse SBF-5 in the panel under the hood needs to be checked to make sure it is good. If that is okay then your next check for a problem should be the Main Relay, that may be behind the passenger kick panel. Having a factory wiring on hand and refer to is very important with these kind of problems. |
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07-29-2020, 08:20 PM | #11 | |
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Quote:
2- If the alternator is completely disconnected is there a short? 3- If there's no short, try untaping the large cable and touching it to the alternator stud it connects to. If it sparks, obviously there's an internal short as previously mentioned. If not, connect it temporarily with the nut. 4- Now put your meter on the battery posts to watch voltage. Connect the alternator connector with the small wires and watch battery voltage to see if it drops rapidly. If it does, there may be something wrong with its internal regulator or it may be receiving a turn on signal from one of the smaller wires in that connector. If it's trying to excite the field coil for no reason, it could draw a good amount of current when it's not spinning. That's my best guess from the information you've provided so far. Like others have said, if wiring is damaged elsewhere, it could be messing with the alternator charging circuit. If any of us were there, it would probably take a max of five minutes to figure it out. Web diagnosing sucks, lol. |
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07-29-2020, 10:19 PM | #12 | |
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Quote:
I have a frankensteined wiring harness so unfortunately no wiring diagram will be able to help me :/ I just built my motor a few weeks ago and looks like I'll have to part the car out now |
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08-05-2020, 10:16 PM | #13 |
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guciodog11 - Dang Man! :-\ Sorry to hear that... I feel ya on that issue with yours, had to do part out my Dodge diesel truck like that. But talk about a B**ch of a motor to pull!! Over 1,000 lbs just for the motor complete! :-0
2slofouru - That is some sound advice! And yes, agreed about Web Wiring fixes. Jeez, probably simple. And I'm a smart guy ;-) This is stream of thought, sorry if it's not broken into many paragraphs. So I did that order of checks, with the Alt + cable end wrapped, battery hooked up, then installed the Main Fuse... No short... But the ABS Pump (or whatever it's called) in the front right corner behind the headlight started running some motor sound! Pretty loud, and like a gear drive kind of grind. Not bad sounding, as in it doesn't seem like it sounds bad but I have never heard that dang thing! I can't tell when I lockup the brakes, too noisy at that moment. So I unplugged it for the time being. Touched the Alt + Ring ended cable to it's post (without little Alt plug with wires, but that though on battery drain is a good one to remember!) and POW! Like the old cheesy Comic books! So I went back to my dummy testing... Anyway, I did some other simple checks. Momma always said KISS, Keep It Simple Stupid! When checking the Voltage to see where power would flow IF it were connected. I saw that touching Battery to Alternator case (should be grounded), it read -12vdc... Wait (-)?! I had my Red Meter lead on Positive Batt, and Black on Ground. Checked battery, read -12... So I was going "damn junk Harbor Freight meter", went inside and check multiple small batteries and transformers... Meter is NOT Broken it seems. So my new question is, have any of you had a Battery that was flowing power in the wrong direction??? Or am I going crazy?! I don't have the local Asylum's number on hand New thought, and I would normally just through another battery at it, properly checked and hook it up. Anyone see an issue with that, or is there something I should unplug just incase I have been technically plugging my battery in backwards unbeknownst to me! Thanks everyone! Well, at least I do have a second car thank goodness! And I like to drive it, but still needs some work. 1972 Chevy Blazer K5 4x4, stock driveline, built suspension and 3 link King Bypass Coilovers in front, 8 point cage welded to frame, and paint is the color of Chevy engine block-Orange/Red, with black soft-top! Gas mileage is half the Subie though, argh. Cheers |
08-06-2020, 09:39 AM | #14 |
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If I understand what you are saying about the battery voltage reading correctly it sounds to me that either the battery is connected up reversed polarity or it is reversely charged (don't think that is possible). Place your meter probes across the battery posts, with just the ground wire connected to the battery, and see what the polarity shows. If the red probe shows positive polarity when it is touching the black ground wire side of the battery then the battery is reversed.
You didn't seem to check the resistance, or tell us if you did, of the main output stud of the alternator to ground. This is an important test. But from what you have now stated it seems to me your battery connections are reversed. |
08-06-2020, 01:04 PM | #15 |
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Good Morning,
Tested again right now, just to double check. I know it seems very unlikely, but as it stands right now the Battery Is Reverse Charged. When tapping probes to battery posts properly (Black to "-", Red to "+") the meter shows "-12vdc", and switches to "+12vdc" if I reverse the orientation of probes. I do have the battery cables hooked up properly to the battery as they were before, so they are Not reversed by me. Although the battery internals Are Wrong, polarity inside the battery does not match the labels/markings at the posts, even though the battery Group is the same as what I had. The only part of the meter I don't always use for work or play is the resistance. I do a little work with resistance when soldering LED's. So that area of this testing is where I am not sure what is supposed to be coming from the alternator. I thought I did post the resistance before of the Resistance, but it looks like the number changed with this test. Maybe all the testing with reverse polarity has altered this. The difference from that resistance check to now, is that the Alternator is now mounted back in the car. But both sets of wires on the alternator are unplugged for testing purposes, the Battery, Main Fuse, and ABS Pump in front of the car are also unplugged. (Alternator wires that are unplugged for below test = 1 positive ring end cable, a plug where only 2 of the wires are being connected to the 3 terminals on the Alt. side. Sorry if this is too much info, but I am trying to not miss Anything since your not here seeing what I am seeing ***55357;***56898;) Resistance test of Alternator to it's own other connections with items above unplugged, meter set to 200k Ohms - 124.2 Ohms - Alt. "+" to chassis. (before I seemed to have 16.2 ohms with meter set to 20k Ohms, maybe mounted in the car changed it instead of reverse polarity?) 165 Ohms - Small plug with 3 internal connections Top connection to Alt.+. 253 Ohms - " " Middle connection to Alt.+. 100 Ohms - " " Bottom connection to Alt.+. FYI - Battery is "Interstate Batteries" from Costco, Group 35, items #88550242 Back to the basic issue about the Battery with "Internally Reversed charge" compared to the polarity markings for the Posts. Basically, What happens to Subie's when someone hooks their battery up backwards? I will see if I have time to hook up a standard Battery to Subie and see what happens. I just hope that the battery didn't fry the ECU or other important items. I have only once hooked up a Battery the wrong way after a very long time away, never again! it was my 1960 VW Bus with built motor and upgraded high output Alternator. Something in the Alt smoked! When checking further and with the Fan belt removed, the Alt was acting like an under powered motor. ***55357;***56883; It was spinning when hooked back to battery properly. Subie is Not doing this thankfully. Cheers |
08-06-2020, 05:15 PM | #16 |
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When ever you make a resistance test you need to be sure no power is applied to the circuit you are testing. Since you say that the multiplier of the resistance scale was 200k that means the readings was 124,200 ohms not 124.2 ohms. If you had tried the 2k scale the meter should read "OL" or over limit. The reading proves there is no short to ground. When you make this test you do want the alternator installed in the car, with the wires connected to, it except for the main output lead and the positive battery clamp. Just the ground wire tied to the battery.
You have proved that the battery is reversely charged by using you meter so I don't think you need to make any more resistance tests. Who would have thought you had a reversely polarized battery causing this issue. You stated earlier that this is a new battery, and if so, it needs to be returned for a new replacement. Somebody really goofed up on charging the battery. Hopefully nothing has been damaged by this error, but you will have to check things when you get a new battery installed with the proper polarity. The ECU is protected for this kind of thing by a diode reversely installed to the normal power. It will cause the fuse to blow if power is connected backwards. Last edited by Cougar4; 08-06-2020 at 05:36 PM. |
09-11-2020, 08:59 PM | #17 |
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Hey Cougar4, Thanks for the good intel!
Good News Guys! After dealing with Costco and the return line from hell, but a nice manager... I have the new, and correct polarity battery!! And my Subie starts ... sort of. Okay everything at first check seems great, and car starts easily. Here is the next rub, really not sure if that whole messed up battery did something else. She runs perfect for about 30 seconds, then stumbles like a classic car not getting enough fuel. I know this is drive by wire, and there is no Accelerator pump circuit for when the throttle is pushed. But I tried to keep it running, the only way was to pump the throttle really fast. I hoped it would clear the "air out of the lines" (I don't know if that is a thing for gas, but it was for my old diesel), it just prolonged the "stumble". If I left it alone then it seemed to be consistent. about 30 seconds running great, I could rev it and build boost to get the blow off valve to hiss (after it was warmed up of course, didn't want to hurt a cold engine). Then it would stumble for about 10-15 seconds. I mean really stumble till the Tach could not read and I swore it stopped running. Then maybe one cylinder caught and got it turning again at the last second. I let it go without my foot on the gas, and stopwatch in hand for at least 7 minutes. It was close to operating temps, and all else seemed fine, I did not drive it thankfully. What could that mean??? I was unemployed for months, and hope I don't have to go to the mechanic. Thankfully I have my work truck to drive around, but 10 mpg sucks. Thank you for helping out |
09-12-2020, 02:46 PM | #18 |
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I suspect the trouble you are now having is due to lack of fuel pressure. This could be because there is a problem with the fuel pump controller, a faulty relay, the fuel pump itself, or the wiring connection to the pump. To see if the problem is fuel related you could spray a small amount of starter fluid into the intake when the engine starts to act up and see if the engine acts favorably to that. It may be good to replace the fuel filter also as a first step.
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09-17-2020, 11:45 PM | #19 |
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Good to see that old school rodder tricks still work on engines with brains (ECU's)! I forgot to reread before heading out there can in hand, I didn't replace the fuel filter. Probably should anyway. But good news, I got a reaction. The Stumble picked up to a clean rev up each and every time, for a handful of times.
It was running just great before this whole battery thing! I'll get on that filter, but what do you think it is? Or how I can test this? I know how to test the relay |
09-18-2020, 09:32 PM | #20 |
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Hopefully replacing the fuel filter will fix the issue. If it doesn't then you should check the fuel pressure to make sure the pump is working correctly.
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11-10-2020, 11:01 PM | #21 |
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It's surprising how fast time goes by! Jeez! I'm back on this again.
I pulled the fuel filter and pump. before I "waste time buying what I might not need, I cleaned and tested it before I'll put it back in. Fuel filter did well on blow through test, after draining the fuel backward into a cup. I then ran thinner through it backwards, a little bit of dirty gas. Nothing that blocked the flow. Seems like it can go back in. I'm trying to save money during these times, and it seems high to me that I see $70 for just a filter. Next I did a simple test, just the first thing that came to mind. I hooked up a spare pressure gauge direct to the pump and powered it up. I got 30 psi, is that standard? Thanks a mill! |
11-11-2020, 01:48 PM | #22 |
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I seem to recall that the fuel pressure from the pump should be around 70psi for fuel injection and the regulated fuel pressure should around 30psi but I'm not certain of that.
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11-11-2020, 06:31 PM | #23 | |
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Quote:
The shutoff discharge pressure for an '05 model is between 64 to 99 psi according to the manual. The discharge pressure is 45 psi. I think you may need to replace the pump if it is getting the proper input voltage to drive the pump motor. |
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