I Think I Fried My Canister Purge Solenoid Circuit

[Soul Shinobi]

Now I know this thing has a lot of names; the solenoid in question allows venting from the carbon canister into the intake manifold and is often abbreviated CPC Solenoid in Subaru literature.

Now, I'm an idiot and jumped the terminals on the connector for this solenoid, because I though it was the connector for the coolant temperature sensor (I wanted to trip the radiator fans).

Now my idle is bouncing about causing the car to stall sometimes, and the check engine light won't go out: code 35, CPC Solenoid.

I've tried clearing the ECU, this issue is still present. I checked all the fuses, they're fine. I've put voltage to the solenoid and it works.

I then went about testing it as follows:





Alright, now, the second to last test could be a possible issue because I got a resistance of 13k Ohms between connector E11 terminal 2 and ground, I would think this should be either much higher or even Out of Limit when the ignition is off. This might indicate that the transistor in the ECU is bridged.

The last test yielding 600k Ohms of resistance between connector E11 terminal 1 and battery cable positive is odd because both battery cables were disconnected from the battery and the power would have to flow through the ignition relay. I would think resistance would only be 0 Ohms as specified only if the ignition was on, which it couldn't be in the prescribed test conditions.

One of two things (or both) are damaged based on this data. The power side of the solenoid's circuit, which could be:
-Wires (doubtful, but technically possible)
-Ignition relay (doubtful, but technically possible)
-Fuses (already checked fuses, they're fine)

Or, the ground side, which consists of:
-Wires (tested out okay)
-Transistor in the ECU (oh shit, could be possible because I got a resistance of 13k Ohms between connector E11 terminal 2 and ground)

I really really really hope I don't have to replace my ECU. What do you guys think? I just don't know where to go from here. EDIT: Is there a parameter on Vikash's scan tool I could check out?

Cross-posted to NASIOC.

[glennda5id]

You can pick up an ECU for $50 on ebay. What year car, and is it turbo or N/A.

Also, why would you jump the temperature sensor, I think it runs on 5 volts which is provided by the ECU so jumping it with 12 would be dangerous.



Also, you can turn the radiator fans on by connecting both the black and green diagnostic connectors and turning the ignition key to ON. It will put the car in a mode where it will cycle them on and off.

You should also look at getting the scanner software that was developed by vrg3. It doesn't seem to be hosted at his Cornell page any longer and b10scan.com doesn't seem to work. But someone on the board should have it.

[Soul Shinobi]

I know, I think I will be getting an eBay one unless I can get one from a junk yard or my WTB post in the parts shed soon.

1992 Legacy L Sedan AWD N/A 5MT.

I wanted to be sure removing my A/C relays (since I got rid of the A/C system) wouldn't impede the main fan operation. I only jumped it through the connector, I didn't put 12v to it.



I didn't know about that particular test method, thanks.

I do have the scanner software, actually, I haven't run through it recently but I don't think it could tell me for sure the cause of the problem. I think I will check it out though, just in case, thanks.

[glennda5id]

I know that some of the A/C relays do control the fans. Not sure which ones though.

[Soul Shinobi]

Turns out they're not needed, the Main Fan Relay has primary control.