Sure will TJ - Works on everything Pre Bugeye.

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Wow, great stuff. I just googled "2000 wrx check engine light flashes 4 slow 5 fast" and this thread is exactly what I needed.

Quick question for Rossco, you seem real familiar with Subaru factory info. Is there any recommended troubleshooting procedure for that pressure switching solenoid? Are there any known issues with a code 45... like is it probably that the solenoid is sticking or is it more likely an issue with the circuit? How does the ecu detect that fault?

I registered a profile on this forum because there's just so much more info available than any forum stateside. NASIOC has some info available for the gc8 swap, but nothing like this. This is great stuff.

Hi Mate,

The ECU looks for an open circuit or low resistance (Short) in the pressure exchange solenoid circuit only - it's not a clever system by any means.

If you put your ecu into 'check mode' it will cycle all the engine system relays including the pressure exchange solenoid and boost control solenoid - I'd start with hitting the solenoids plug pins with contact cleaner and then using a multimeter to see if voltage is reaching the solenoid when the ecu is in check mode.

Hope that helps!

P.s check mode is enabled by plugging the two green connectors together and switching the ignition on.

Rossco

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I'm checking all around the circuit, I even jumped the solenoid to battery ground and power to make sure it works (and it does, I even blew through it to make sure the solenoid was switching the air flow), and I can't find a problem. The solenoid does not tick when the check mode connectors are connected and the ignition is on (eng off), but I can't figure out why.

For clarification: this is a USDM Impreza 2.5RS with a JDM(?) EJ205 swapped into it. I bought the thing from Canada; it came with the harness and ecu. I spliced the harness myself using a combination of NASIOC posts, PossumLink's V5 wiring guides, and USDM RS wiring schematics as guides. The car runs and drives, but the check engine light is on and the ignition(?) cuts out under boost. I'm really hoping it's not the ECU. I just bought the damn thing.

Um... some specs I pulled looking at it tonight:
Voltage drop across the solenoid is only about 2 volts while the check connector is connected and the wastegate solenoid was clicking away next to it. Resistance is in the 40-45 ohm range, like I said.
Measured 0.2 ohms between the ecu pin (B134/26) and the solenoid ground side (both connectors unplugged).
Measured 0.002 volts between the solenoid power side pin and battery plus (with the ignition on, 12.65 volts with the ignition off).

Any suggestions?

Check the voltage from the positive pin on the harness direct to chassis earth when the ignition is being switched from off to on.

Also do you have the MAP sensor plugged in?

You should have the following components wired in:
Boost solenoid
Pressure exchange solenoid
MAP sensor

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Yes, power to the plus side of the pressure exchange solenoid connector with the ignition on.

The map/boost sensor is plugged in, the wastegate sensor is plugged in and clicking away when the ecu is in check mode. The vacuum lines are connected properly, securely with no cracks and no blockages. I know the exchange solenoid is seeing engine vacuum and so is the map.

I compared the voltage reading to the power side of the wastegate solenoid and it looks the same as the exchange solenoid. I don't know if my DVOM isn't fast enough to display the rapid switching. I would expect the voltage reading to drop when the ecu applies ground to the solenoid, but I'm just seeing steady battery voltage to both solenoids...

I checked that there's continuity from the solenoid ground (earth to you) side of the exhange solenoid connector to the ecu. Is there anything else I should be checking?

I was thinking maybe the code is just setting from having the connectors unplugged during all these diagnostic steps, but every once in a while the check engine light goes out and then comes right back when I try to get on boost.

I'm worried because if it's as simple a circuit as you say, I've already ruled out the wiring and the solenoid... which looks like the ecu isn't switching the solenoid on.

I'll try to get pictures up if you think it'll help.

Bump.. for a good old thread

I found this post after my CEL came on.

I don't know if I'm missing something. I have a US-spec 2000 GC8. I don't see two black connectors anywhere. I see the green ones and three black ones but the three black ones do not seem to be able to connect to each other. Attached is a picture. Am I missing something?

Please help. Thank you.





If the images don't work, the album is here:

https://imgur.com/a/leaDx

what do the green ones do?

found it under stock-ecu-discussion.. where they are both connected as part of the reset process