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Old 02-23-2004, 01:53 PM   #1
Hawk296
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Default Idle air control valve circuit

Yet another problem with my 1995 impreza L. 5 speed AWD 1.8l

Something is draining my battery. The other day the car wouldnt start (fast clicking from the starter solinoid). Popped the hood and heard a high frequency electrical noise like a transformer. I traced it to the Idle air control solinoid. I unplugged it and it stopped. Then car also started at that point. With the idle air control valve disconnected I checked voltage with a multimeter across PIN # 2 and PIN# 3 on the wiring harness end. I was getting alittle over 12V with the car turned off and the key in my hand.

My question is, is this normal? should I be getting power to the IAC when the car is off? It doesnt seem right.

Also, what controls this circuit? Is there a relay somewhere that can be stuck? I have the wiring portion for the engine harness and then I have the copy of the ECU pinouts but I dont have the electrical diagrams for in between So I cannot see components in between. Any ideas?

Thanks a ton for any ideas you may have...
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Last edited by Hawk296; 02-23-2004 at 04:47 PM.
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Old 02-23-2004, 04:48 PM   #2
Hawk296
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any ideas?
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Old 02-23-2004, 09:08 PM   #3
avk
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There shouldn't be battery voltage at IAC with the key off. EFI devices are powered through the main relay, and the grounds are controlled by ECU (someone please correct if this is wrong). Are you sure nothing gnawed on the bulkhead harness? That might explain it all, including ABS. Anyway, you probably need wiring diagrams.
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Old 02-23-2004, 11:17 PM   #4
Hawk296
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Yeah thats pretty much what I was thinking. Hmm Ill look closer at the harness tomarrow. There are some really strange people in my apartment complex, maybe they decided to snack on my wiring haha.

I definatly think my misfiring/stalling problem is related and also considered my ABS as well. We will see.

I just need to get the car to MI on fri...

Thank you so much for replies!
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Old 02-23-2004, 11:26 PM   #5
Castle4kq
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#1 Fix all

1) splash gasoline throughout and under vehicle

2) apply spark for ignition.

3) call insurance
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Old 02-24-2004, 12:23 AM   #6
Hawk296
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HAHA! I am so almost at that point right now....
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Old 02-26-2004, 10:27 PM   #7
vrg3
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I had trouble with my sensors and solenoids being powered when the car was off too. I got in the habit of disconnecting my battery when parking my car.

I did eventually trace it to a bad ignition relay. I got a replacement from subaruwrxparts.com, put it in, and all was well.

I do believe the IAC valve is powered directly from the ignition relay.

Apparently Subaru used to use better ignition relays. Loyale ignition relays have platinum contacts, so they don't wear out nearly as fast.
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Old 02-26-2004, 11:43 PM   #8
Hawk296
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Thats crazy, thats exactly what I have been doing everytime i go somewhere, connect the battery, then disconnect when i get out. It just has to get me through tomarrow so i can make it back home.

Thanks for the info, I'm definatly going to check into the ignition relay. Where is that located in the car?
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Old 02-26-2004, 11:48 PM   #9
vrg3
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Assuming it's in the same place as in my Legacy, it's in a very annoying place.

It's mounted behind the driver side dash, way up high against the firewall. I was able to reach it by sitting cross-legged on the floor facing away from the car, and reaching up with my right hand. There's a cylindrical metal relay which is the fuel pump relay, and a brown rectangular one which is the ignition relay. The ignition relay is somehow snapped into its mounting bracket and I was never able to figure out how to get it off. I just disconnected the harness from it and mounted the new relay elsewhere with zipties.
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Old 02-26-2004, 11:53 PM   #10
vrg3
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Actually, before I was able to source a new relay I did come up with a kinda cool workaround.

SBF-2 in the underhood fuse box was responsible for feeding power to the ignition relay's contacts. So, I stuck spade connectors into the fuse box and wired a relay in series with the fuse. Then I had the coil of that relay driven by the parking light wire. The end result was that power was cut to the whole engine management system whenever the parking lights were off. Since they cut off automatically when you turn the car off, that worked well. As a bonus, if I turned off the lights manually, the car wouldn't start -- an anti-theft device.
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Old 02-26-2004, 11:54 PM   #11
Hawk296
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haha, so youre still carrying around a dead relay!? awesome.

Seriously though It probably is in a similar place seeing how subies are so alike. Ill check it out. It really sounds like this could be it. Its been driving me nuts. Thank you much.
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Old 02-27-2004, 08:34 AM   #12
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The ignition (a.k.a. main) relay is plugged into the harness that goes through the firewall. It's indeed brown and has two pairs of switching contacts, so spotting it shouldn't be very hard. But it's much easier if you remove the lower trim panel.
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Old 02-27-2004, 02:00 PM   #13
vrg3
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Hawk296 - Yup... The whole ordeal has now made my car slower due to added weight.

avk - It must be easier to see on GC/GFs than BC/BFs. On my car it was hard to see even with the trim removed. I ended up doing it by feel because I could never see it and touch it at the same time.
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Old 02-27-2004, 08:40 PM   #14
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Yes, on 1st gen. Legacy it may be harder to work in the footwell because ECU is in the way, and on your (vrg3's) car likely the cruise control, which a '95 Impreza wouldn't have from the factory.
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Old 03-06-2004, 02:59 AM   #15
Hawk296
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ok so i have located the main relay. It is indeed getting stuck on but its not the relay. I bench tested the relay and it works fine. It also returns to its open position when the battery is disconnected and reattached. It stays this was until the key is turned and the ECU engergizes the relay again. THen once energized the main relay stays that way (with 12V running through the coil) when the key is off and removed.
There are two large 16 pin connecters that connect the engine harness to the main harness that goes through the firewall. One is grey and one is blue. If you disconnect one of these there and leave the otehr connected the relay works fine and switches on and off with the key. When both are connected the relay gets stuck on until its reset by removing power all together by disconnecting the battery cable. I have been chasing wires all day. This defys all logic and I am completly burned out from it.
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Old 03-06-2004, 03:06 AM   #16
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Quote:
Originally posted by Hawk296
ok so i have located the main relay. It is indeed getting stuck on but its not the relay. I bench tested the relay and it works fine. It also returns to its open position when the battery is disconnected and reattached. It stays this was until the key is turned and the ECU engergizes the relay again. THen once energized the main relay stays that way (with 12V running through the coil) when the key is off and removed.
There are two large 16 pin connecters that connect the engine harness to the main harness that goes through the firewall. One is grey and one is blue. If you disconnect one of these there and leave the otehr connected the relay works fine and switches on and off with the key. When both are connected the relay gets stuck on until its reset by removing power all together by disconnecting the battery cable. I have been chasing wires all day. This defys all logic and I am completly burned out from it.
I worked with Hawk296 for a few hours tonight on his car, and I want to add that we checked for shorts through the sensor side of the gray harness, using a continuity test on each pin. We originally thought we had found a short, but it turned out to be an injector that we had left plugged in.

I'm by no means an electronics wiz, but I do know my way around fairly well, and this has me completely stumped. The relay is switched on by 12v from the ECU (light green wire). We tried swapping out the ECU, and it did the same thing.

So we've basically eliminated a bad ECU, bad sensors, bad harness, bad relay.

Any other suggestions?
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Old 03-06-2004, 11:45 AM   #17
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All that comes to mind, maybe the "cold" side of one of the two switched circuits somehow came in contact with the positive side of the coil inside the housing. Then the relay would become self-latching. Can you disconnect the relay and check for continuity between the pin that connects to light green/white, and the other pins? You should only have continuity across the coil.
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Old 03-06-2004, 12:39 PM   #18
Hawk296
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With the relay unplugged, there is no continuity between any of the pins ecept the the Light green wire that connects the ECU to the coil and the ground for the coil which is directly across from it. So there is no continuity except for across the coil.

with the relay powered to the closed position, there is continuity between the two pins that normally are connected to B+ and their respective pins. This to me indiactes that the relay is operating correctly with no internal shorts.

I also got a jumper wire and 12V and put 12V to the two pins that are normally hot from the battery and grounded the other two. Then added 12V to the coil to make it switch (thinking that once it was switching it was shorting internally to the coil keeping it powered) but as soon as I removed the 12V from the coil it disconnected and opened up.

So overall I tested the relay just about everyway i knew how and it passed all my tests. I even connected the relay to the harness via jumper wires one at a time and everything works fine UNTIL the dark green wire is attached. Everything but this green wire can be attached and it switches on and off fine. As soon as the dark green wire is attached it will switch on and get stuck on.

This dark green wire is the one that runs from the relay to the MAF and to power the injectors. That is what led me to try and disconnect that side of the engine harness from everything else discovering that once its disconnected it works. From there we disconnected every component and tested continuity as mentioned above.

I am going to take everything off, fab up a manifold, and switch to a carburator and distributer. haha.
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Old 03-06-2004, 01:10 PM   #19
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Is the ECU's "ignition switch" pin getting voltage for some reason?
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Old 03-06-2004, 02:34 PM   #20
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When applying 12V to the "hot" switched contacts with a jumper, why did you ground the other two? Can you test it w/o grounding? To positively exclude an internal short, there has to be 12V at the "cold" side. If I misunderstood, never mind.

Add: The green wire connects to ECU, too. So what happens when you unplug it looks like correct behavior. At this point I second vrg3's opinion.

Last edited by avk; 03-06-2004 at 10:08 PM.
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Old 03-08-2004, 12:37 AM   #21
Hawk296
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I had to head back to IA today so i didng get much time. But I did aquire a new main relay from another car. It is for sure a good relay but when in my car gets stuck on also. So I can now safetly rule out the relay and look deeper into the circuits it connects to and the ones that control it.

And youre right that green wire does go to the ECU also....

And last night I went back and Re-checked all my fuses (have done this already and all were good) But this time the 20A fuse for the "main fan" was blown. I replaced it and so far all is good on that end of things.
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