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Old 03-06-2013, 09:28 AM   #1
jdmftw88
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Default Don't know what's going on help!!!

My 02 WRX wagon (2.5 shortblock, vf34, sti int, sti inj, gimmick intake piping (stock filter) and gimmick catback, noname downpipe w/ cat) is having issues on starting up...one day it just cut out on me on the highway, and ever since has been cutting out on me once and a while, usually starting right back up. I replaced the fuel pump, which seemed to help for a little, but still cut out. now, when I try to start the car, the "check engine" light does not come on in the key-on position, which it should. I am told by my friend also subaru mastertech that this means the ecu isnt communicating or getting power...I checked all fuses, they all are good to go. I'm thinking it could be a relay(?) but dont know how to test this. the main relay does click over when you turn the car to on, every time, check engine light coming on or not. It wouldnt start last night at all, I spent 3 hours trying to fish for the problem. Got a ride home with my dad. This morning came in to work, and for ****s and giggles decided to try to start the car. Check engine light came on, and it started right up, normally. I let it run for a cpl of mins, then shut it off and tried to restart it. No check engine light, no start. My question is what the heck could possibly be so intermittent that it fixes itself even tho the car hasnt been moved overnight, then goes straight back to not working again?! This is the most aggravating problem I've had with a car because its so tempramental you cant even depend on your own car. Any insight would help. Looking to fix this asap so I can actually use my car without worrying if it will start or not again ...thanks for your input in advance!!!!!
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Old 03-06-2013, 12:13 PM   #2
Cougar4
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Well first off my hat is off to you for thinking about the Main Relay as the problem. You very well could be right about that. If you don't have at least a test light probe to test for power with I suggest you invest in one. Getting a voltmeter would be even better but you don't have to get one to find this trouble.

Fuse SBF-5 in the main panel under the hood should supply power to the relay. Make sure that fuse is making good connection. Also use the test probe to check the power getting to both sides of the fuse while the trouble is happening and with the key turned to ON. If the fuse is ok then you need to check the relay next. The relay has two sets of contacts so each set should be checked. I think you will find either the relay is the problem or the ignition switch is at fault for this issue. The ignition switch provides power to the ECU I believe and the ECU controls the relay turn on if I remember correctly.

My info shows power from the fuse ties to blk/red and blu/red wires on the relay and the contact to yellow wires on the other contacts of the relay. To see if the ignition switch is causing this trouble check for power on fuses 8,11,17,and18 in the dash panel while the ignition is on. If you don't have power on those fuses then the power to the ignition switch needs to be checked.

Last edited by Cougar4; 03-06-2013 at 12:31 PM.
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Old 03-06-2013, 01:07 PM   #3
jdmftw88
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thanks for the help! I have a harbor freight test light, and also a voltmeter, so will have to go get them from home tomorrow and bring it to my car here at work, thank god we have the spare truck. Is there any way of telling if a Slow Blow fuse is blown by inspecting it? I actually switched out SBF5 with SBF6 just to see if that would fix the problem (they are the same amps) obviously did not fix it. I actually popped the clear caps off all the SBFs to take a better look at them, they all look clean/unburnt/unseperated. And how could it be the ignition if the ignition is successfully always telling the ABS, SRS, and the starter to turn on? Or are you just saying just the circuit from there to the ECU might be fried/shorting? either way, I'll look into it. that would be a valid explanation, at this point I'm hoping thats the problem.
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Old 03-06-2013, 06:15 PM   #4
Cougar4
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You're welcome for the help and it's good to hear you have the test tools we need to help find the trouble.

You should be able to visually see if one of the SBF fuses is blown and not have to remove the cover to do that. While the fuse may be okay and chances are power is getting through it, you really don't know for sure until you test the connections for power. As for the dash fuses they do provide power to some of the areas you mention so are most likely ok but it is just an easy place to check if the ignition switch is suspect. The most likely area for the trouble is the Main Relay or a connection to it. I don't think anything is fried, you most likely have a bad connection that is causing this trouble. It could be the relay or in a connector possibly.
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Old 03-07-2013, 08:56 AM   #5
jdmftw88
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ok cool. I grabbed all the tools today, and yesterday I actually got the car started and had enough balls to drive it the ten or so miles over to my buddy's subie dealer (un:carnz-pj-410), it actually cut out on my once in the parking lot after starting it, then on the way there once again, both times started right back up thank god. but now the problem is that I cant get the check engine light to not come on like two days ago, so I'm gonna try to futz with it again today but if I can't get anything to happen I might just order a new ignition switch because thats the only thing that makes complete sense at this point anyway.
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Old 03-07-2013, 11:54 AM   #6
Cougar4
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Well if it was me I would start with the Main Relay as the first guess. Intermittent problems like this can be hard to pin down and they seem to happen at the worst times. One other thing that could be going on is the grounding for the ECU may be at fault. Check the ground at the rear of the engine at the top of it. Make sure it is tight. You very well may find out this is a ground issue rather than a problem with the power side of things.

Keep at least the test light probe in the car in case the trouble happens and then you can at least easily check the fuses mentioned earlier in the dash panel to see if they have power getting to them.
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Old 03-07-2013, 12:15 PM   #7
jdmftw88
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Quote:
Originally Posted by Cougar4 View Post
Keep at least the test light probe in the car in case the trouble happens and then you can at least easily check the fuses mentioned earlier in the dash panel to see if they have power getting to them.

That's an awesome idea, I'll definitely do that.

and also about the grounds, I'll try to locate them and check them this afternoon after work

dude thanks so much for your help it always leaves me with a good feeling when people reach out to help each other on the forums like this. I'll check back when I get an answer or if i run into something else...
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Old 03-07-2013, 12:52 PM   #8
Cougar4
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You're welcome for the help. There are a lot of helpful folks here at this site.

Another thing you could do is purchase a small 12 volt light and tie it to one of those fuses mentioned and place the light on the dash somewhere you can easily see it while you are driving. Then when the trouble happens either the light will still be on or off and you will know instantly if the problem is with the switch. Frankly I doubt it is, my money is on a bad ground or Main Relay as the cause of the trouble.
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Old 03-07-2013, 04:20 PM   #9
jdmftw88
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oh ok. Thats a great idea as well. And I wonder how much it is to replace the main relay anyway. Could something actually still be wrong with it even though it definitely clicks over every time I turn the key pos to "on"?
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Old 03-07-2013, 06:10 PM   #10
Cougar4
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Yes, the relay contacts can and do go bad and unless you test them while the trouble is occurring you won't now if they are really good or not. Replacing the relay would be an easy thing to try if you just want to give that a shot. Also tapping on a bad relay while the problem is happening can often make it work again and verify it is bad.
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Old 03-12-2013, 01:07 PM   #11
jdmftw88
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so I tested all the fuses and SBF's while I had the trouble going, and they came back all good. One of the power wires to the ecu from the main relay is measuring out to 1.9 volts, the rest checked out at 11.9...I thought I was reading it wrong but I triple checked, definitely is saying 1.9 not 11.9. I believe this is the yellow/blue wire coming out of the relay. We're going to further check into it later today, my buddy at subaru has the whole ecu/relay wiring diagram so we'll trace it according to see if theres a voltage drop anywhere.
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Old 03-12-2013, 02:35 PM   #12
Cougar4
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You are making good progress. The trouble is most likely due to the relay contacts but there may be a problem with the input side of the contacts. My info shows pin 5 of the relay has a blk/red wire suppling the power from fuse SBF-5 to the wire of concern. See if you have 12 volts at that point. If you do then the relay is bad. Jumpering that connection will prove it. There is also a connection in the line (B66 pin2), after the fuse and before the relay, that could be where the trouble is.
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Old 03-14-2013, 01:03 PM   #13
jdmftw88
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my subaru mastertech friend just worked on it and diagnosed that its actually an ecm failure...which would also explain everything. thanks for your help man, I see a used ecm on the classifieds, will try to buy that, once it comes in I'll check back and post if it fixed it or not. ugh, gonna have to re-flash this ecu now, running open source currently
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Old 03-14-2013, 05:30 PM   #14
Cougar4
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I assume you are saying that the ECU is causing such a high current load on the power supply wire from the Main Relay that the voltage is dropping down to 1.9 volts and if that is the case that would be really bad. The trouble might be due to a bad diode or capacitor inside the unit and might be pretty easy to find and fix. With such a high load I'm surprised it didn't blow a fuse, assuming that idea is correct.
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Old 03-14-2013, 08:52 PM   #15
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I pulled the cover off his ECM today and could not find any burnt spots, failed resistors/capacitors, etc.

Our friend has one in his garage so jdmftw88 picked it up this evening and i should be swapping it in tomorrow to test
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Old 03-14-2013, 09:41 PM   #16
Cougar4
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If there isn't a problem inside the ECU then the low voltage that was measured on the power lead earlier would have to be due to a problem with the relay or in the connection to it. Check the resistance to ground on the pin to the ECU the wire from the relay ties to. See if it is less then 10 ohms.

Unless the ECU is getting 12 volt power on that lead I don't see how the ECU could be proven to be at fault. If there is only 1.9 volts on that lead then the ECU isn't getting proper power to it.
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Old 03-14-2013, 09:57 PM   #17
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Going thru the tests in the service manual and the whole trouble tree it leads to "replace ECM", have not found a single faulty wire on the car or bad connector.

No connection to ground at all on that wire, multimeter reads "OL" showing no short to ground.

Don't worry man I know how to do electrical

main relay also passes resistance checks, when energizing the coil you can feel and see the switches engage on the other 2 circuits, and proven with multimeter.

i also re-tested the wires that were checked the other day and I could not duplicate the 1.9v concern

B134 pin 6 also is not outputting at least 10v like required in the SM, as tested this morning got 2.37v when tested to chassis ground thru the meter


lol sorry for all the updates, adding info as i check the notes i was taking earlier

Last edited by carnz-pj-410; 03-14-2013 at 10:04 PM.
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Old 03-21-2013, 09:12 PM   #18
jdmftw88
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update, it is fixed! turned out to not be the ecu, but it is my understanding it was the power wire coming from the SBF#5 to the fuel pump controller. In the middle of it, there is a connector, it was from the connector to the pump controller that was missing voltage somehow or had a voltage drop there or something, guessing bad connection, cant remember what carnz said. A new line was run to the two points and wire replaced, problem fixed. fuel pump primes, check engine light comes on at proper time, etc etc responding/operating normal now. What a bitch of a job! Thank you so much and thank you carnz-pj-410 for dealing with it I owe you a lot!
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Old 03-21-2013, 09:24 PM   #19
Cougar4
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Thanks for the update and glad you got it fixed. I checked out pin B134 pin6 and see that it carries 12 volt power from the ECU to turn on the Main Relay coil. Connector B97/R1 pin 7 supplies power from the fuel pump relay to the fuel pump controller and may have been where your problem was at.
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Old 03-21-2013, 10:16 PM   #20
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There was an open on the BR wire that comes out of SBF-5, it splits into 2 BR wires in B61 terminal 2 and terminal 8, the wire going to terminal 2 was open.

I ran a new wire and then checked all my circuits again and the car ran

The failed wire was causing a false failure pointing to the ECM in about 4 different tests. When he came to pick it up today I showed him all of my notes and test results throughout the process.

The broken wire directly fed the fuel pump relay and 2 terminals on the ECM for power through the main relay.
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Old 03-21-2013, 10:33 PM   #21
Cougar4
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I see what you are referring to in the drawing. It appears there is a splice somewhere in the line coming from the fuse and now makes two wires. Good job on the find. This kind of problem demands that all the power supply lines need to be properly checked in order to find the trouble.

I noticed that the wire supplies power directly to the data connector along with the ECU and to the Main Relay.

Last edited by Cougar4; 03-21-2013 at 10:39 PM.
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