Apart from the solenoid being knackered is there anything else that can stop it from operating, Is it fused or anything?

I connected up the green plugs under my steering wheel and it doesnt click, My fans spin up and I can hear various other things clicking away.

 

Before going any further are you absolutely sure it isn't operating? Sometimes they don't click audibly so try physically touching the side of the solenoid barrel, or even detaching it from the car and blowing through it before assuming it 100% to be dead.

As for your first questions, there are a couple of other things that could prevent it from operating when the ECU is in test mode. A wiring fault is one possibility, as would (even more unlikely) a failed driver transistor in the ECU.

If you're sure the solenoid isn't operating in the car, to determine definitively whether it, or something else is to blame, take it out and try powering it up directly with a 12 volt battery. If it works, you know the problem's elsewhere. If it's still dead...

 

Yea I tried touching it, I also put a screwdriver on it and tried listening through that. Ill take it off tomorrow and try connecting it to a 12v battery, see how that goes. Just sitting bored at work and wondered if there was anything else that could upset it but both the things you just said sound unlikely.

 

Ok I hooked the solenoid up to my battery and it clicked away ok. I connected the green plugs again and put a volt meter across the plug for the solenoid and it read 10.5 - 11.2 volts which is just slighty lower than my battery. It reads that constant though, surely it should come and go ?
What would cause it to stay energised all the time?

Also when it is connected to the car I cant blow through it which I could when I energised it using my battery

 

bttt

 

Confusing!

Probably not. Without a newage ECU in front of me I can't be 100% sure what you "should" be seeing under normal conditions, but it's significant that you say the voltage is lower than the battery.

The solenoid is driven by a transistor rather than a relay, so rather than "coming and going" in a completely binary manner as you're thinking, a little bit of leakage would probably be considered "normal" - it certainly is on the late classic ECUs.

As above I doubt there's enough there to actually energise the solenoid. You'd expect the voltage to be the same as (or within hundredths of a volt of) the battery if the transistor was fully on.

That supports the theory that the solenoid is good. It also makes clear that, despite that residual voltage you've found, it isn't energised when installed in the car.

Seeing as you have a DVM, first thing to do is to run a continuity check between the negative (pin 1) of the solenoid connector and the chassis. If that checks out, repeat the process with the other pin and its opposite end on the ECU connector. The fact that you have voltage suggests it's good but it'd be handy to know if there's any resistance.

If that all checks out, then either the ECU is disallowing boost for some reason or the driver transistor appears to be damaged. One obvious question before we go any further - your check engine light isn't on, is it? If it is, chances are the ECU is in limp mode, although this shouldn't affect what the solenoid does in test mode. On that basis, as above, have a look at the wiring in the first instance.

 

Hooked the car upto to my mates obd 2 software last night and there was an error code up for the solenoid, I think that came up as I turned on the ignition without the solenoid connected, I reset that so hopefully its still gone. Ill try those things you suggested tomorrow and let you know, I cant remember the exact reading of the battery voltage but it wasnt much higher than the voltage across the solenoid plug. Ill do it again.

Thanks for the help, greatly appreciated

 

Was just out messing about with it again before it got dark. Didnt have time to check the continuity between the plug and the ecu like u said ill try get that done tomorrow.

What i did do was check the battery voltage and the voltage at the connector. Battery was 11.4 and the connector was 10.4 - 10.9, it kept wandering about.

The thing that is puzzling me is when i use my dvm when the solenoid is connected i get 0 voltage, Surely even if there wasnt enough voltage to energise it youd still expect to see a reading across the solenoid?

 

Ok everything checks out ok with the solenoid unplugged but as soon as i plug it in the ecu cuts power going to it. Anyone know why it would do this? Had a look to see if any alarms were standing again but apart from 'sumthing to do with heater control' which i beleive is because im running with no back cat there is nothing else.

 

anyone any idea why the ecu would do this?

Just realised I hadnt mentioned my car is a bugeye wrx jap import