ecu/electrical problem

bluesubaru · Post by **bluesubaru** » Sat Jan 15, 2005 12:40 am

Okay my problemo is this...
I have a 95 Legacy L, EJ22-T, wrx turbo and IC, with the greddy emanage. The emanage has been installed while the car was NA for about 4 months with no problems, and been on the car turboed for about 3 weeks. No problems at runnning 5psi.

While coming home from school and idling at a light, my car just turned off and would not restart. There was no bad idiling or check engine light. I have new plugs/wires/battery/starter in for the last 3 wks. No low oil or coolant.

While looking over everything I see that I have a blown fuse, sbf #2. I replace it and it blows again. So I am thinking I have bad relay or ecu. I took off the emanage and it only blows when the ecu is plugged in. I unplug it and it doesnt blow.

What do you all think?

mikec · Post by **mikec** » Sat Jan 15, 2005 1:46 am

Maybe a short somewhere in the ECU wiring? That might take some time to manifest itself, as it would be okay until you moved a wire just right (or wrong, in this case).

bluesubaru · Post by **bluesubaru** » Sat Jan 15, 2005 2:51 am

what do you mean a short in the wire, I mean how does that occur and what do I need to look for?

mikec · Post by **mikec** » Sat Jan 15, 2005 2:58 am

A blown fuse to me automatically indicates a 12V wire is being grounded, which causes too much current to flow through the wire, and blows the fuse.

Unless someone comes up with anything else, I would start by making sure that any wires you had to join when you installed the emanage are properly insulated. Also, you could check for continuity between the emanage wiring and ground without the computer installed. Any wires that aren't intentional grounds that show a path to ground are shorting. Unfortunately, that may be a temporary condition dependant on how a wire is sitting. So definitely start by making sure everything is taped or heat shrinked, so that there's no chance of anything touching the frame.

After that, you may have to look at the emanage being bad.

bluesubaru · Post by **bluesubaru** » Sat Jan 15, 2005 3:36 am

I thought the emanage was bad, so I unistalled it, and tried it again. I still blew fuses. Besides all my wires were taped up. But just to be safe I undid all the connections and tried to start the car, with no luck. So I got a hold of my wiring diagram for the car, and there is a main relay under the passenger side dash. It might be that, not sure?

mikec · Post by **mikec** » Sat Jan 15, 2005 3:39 am

I dunno... I'm going on my basic electronics troubleshooting skills. I'm not at all familiar with the emanage, and not familiar enough with the Subaru electrical system to be able to help you anymore than I already. Hopefully one of the other guys that has explored the wiring a bit more will be able to help.

Good luck!

vrg3 · Post by **vrg3** » Sat Jan 15, 2005 3:43 am

bluesubaru wrote:I took off the emanage and it only blows when the ecu is plugged in. I unplug it and it doesnt blow.

By "the ecu" do you mean the stock ECU or the e-Manage?

vrg3 · Post by **vrg3** » Sat Jan 15, 2005 3:44 am

A bad relay generally won't cause a fuse to blow.

bluesubaru · Post by **bluesubaru** » Sat Jan 15, 2005 6:38 am

vrg3 wrote:
bluesubaru wrote:I took off the emanage and it only blows when the ecu is plugged in. I unplug it and it doesnt blow.
By "the ecu" do you mean the stock ECU or the e-Manage?

The emanage is unplugged for right now, but when I unplug the ecu, no fuse blows, I plug it in, it goes.

Vrg3,
So what would cause the fuse to blow each time? Would it be the whole ecu?

vrg3 · Post by **vrg3** » Mon Jan 17, 2005 3:06 pm

Like Mike said, it's usually some power wire shorted to ground.

What if you only unplug the biggest of the four connectors on the ECU? Does the fuse blow then?

bluesubaru · Post by **bluesubaru** » Mon Jan 17, 2005 5:05 pm

my ecu connector is all one big plug. I don't have the multi plug like other imprezas/legacys do. My year is special I guess.

vrg3 · Post by **vrg3** » Mon Jan 17, 2005 5:18 pm

Oh, whoops, I forgot you have a 95.

Okay, hmm, well... I don't really know where you should start. ECUs don't typically "go bad" and start popping fuses, but it is possible that the ECU was damaged and now contains a short circuit.

You could try swapping in a known-good ECU from another 95 Legacy, but there is a small risk the car would damage that one as well.

Maybe you should carefully pop the ECU's case open and examine the motherboard closely for any signs of damage. You usually see some scorching or burnt insulation when something shorts and starts misbehaving.

Post by **Legacy777** » Mon Jan 17, 2005 8:20 pm

I replied to your post on nasioc.

On the first gen legacies SBF2 is wired into the ignition switch, fuel pump relay, ecu, and injectors.

Try unplugging the ignition switch, & fuel pump relay. Then plug in the ECU. If you don't blow the fuse, plug the fuel pump relay in or the ignition switch, and see which one blows the fuse.

bluesubaru · Post by **bluesubaru** » Mon Jan 17, 2005 11:05 pm

yeah I got a wiring diagram of my car and saw where that sbf2 goes too (ignition relay, fuel pump relay, ecu, & fuel injectors) . I am not getting spark, obviously.
I pulled the fuel pump relay and the fuse doesnt blow then, so I was thinking its that, but I read that relays dont blow fuses. the ignition relay realy I didnt pull yet.

vrg3 · Post by **vrg3** » Tue Jan 18, 2005 1:20 am

Sounds like a short either in your fuel pump or in its wiring.

You changed the fuel pump when you installed the turbo motor, right? Maybe the wiring has come loose at the pump and the +12v line is contacting the chassis. Check that, and if it's the case, fix it right away! That could easily result in a huge explosion, since it can cause sparks in the fuel tank.

If it's somewhere else in the circuit, you might as well run new 10-gauge wire from the fuel pump relay to the fuel pump. The stock wiring's pretty shoddy. As a bonus you'll get extra fuel flow.

bluesubaru · Post by **bluesubaru** » Tue Jan 18, 2005 3:33 am

hmmm yeah I am going to have a wiring/automotive tech come by and give it a look. I am getting a little frustrated and running out of ideas. All the wires I have checked look clean and fine. Thanks for the help.

vrg3 · Post by **vrg3** » Tue Jan 18, 2005 3:43 am

If unplugging the fuel pump relay made the fuse not blow, the problem is almost certainly the fuel pump wiring. You don't need to pay some tech to figure that out.

Pull the fuel pump and examine its wiring. If it looks okay, run a new wire from the pump all the way to the relay, and put in a new good solid ground. That's very likely to solve your problem.

bluesubaru · Post by **bluesubaru** » Tue Jan 18, 2005 4:36 am

I didnt change my fuel pump, I will, but I havent yet. But I did check my wiring back there and did not see any problems

vrg3 · Post by **vrg3** » Tue Jan 18, 2005 5:24 am

Maybe just try unplugging the fuel pump (with the relay plugged in) and see if the pump is somehow at fault?

You're very close to figuring it out.

Post by **Legacy777** » Wed Jan 19, 2005 7:07 pm

vrg3 wrote:Maybe just try unplugging the fuel pump (with the relay plugged in) and see if the pump is somehow at fault?

You're very close to figuring it out.

That's what I suggested early, definitely try what Vikash & I have suggested.

It will narrow the problem down to the wiring going to the pump or the pump wiring.

bluesubaru · Post by **bluesubaru** » Wed Jan 19, 2005 9:53 pm

yeah okay I tried that, plugged the relay in, and unplugged the pump, it still blew the fuse.

vrg3 · Post by **vrg3** » Wed Jan 19, 2005 9:55 pm

Then it's gotta be the fuel pump wiring, right? Replace the wiring and get your car running again!

If you're upgrading your fuel pump it makes good sense to upgrade the harness, even if the wires aren't short circuited.

bluesubaru · Post by **bluesubaru** » Thu Jan 20, 2005 5:22 am

okay, but what pump, walbro or wrx?

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