06 WRX Intermittent Start Issue
 

Hi,

I have an 06 WRX CS9 with roughly 145,000km on the clock, over the past 5 months it has been having intermittent start issues which I have been unable to determine the cause of. Majority of the time the car starts perfectly however every so often (issue seems to have become slightly more prominent recently roughly occurs once a week now) the car will fail to start. When I turn the key to start, all of the dash lights come on as usual, I can hear the fuel pump priming, the clock light even dims as if the car was starting but there is absolutely no action from the starter motor, no cranking at all. Once in this mode it appears completely random to how many subsequent start attempts it takes before the starter will engage and crank, sometimes the very next try it will start other times it might take 10-30 attempts before it cranks. Once the car has started I turn it off and start it again straight away it always starts perfectly.

Immediately I jumped to this issue being a failing solenoid on the start motor, stupidly without testing the starter motor with a multi-meter I replaced the start motor and unfortunately the issue continued to occur.

My next thought was maybe it was something to do with the factory immobiliser (not the Brant security system which I disabled a number of years back). I was thinking maybe the transponder in the key head wasn't being detected by the ignition and therefore the immobiliser was still active and preventing the car from being started. However I noticed that during one of the times the car was failing to start when I took the key out of the ignition the red flashing key light on the dash would being to flash then when I inserted the key into the ignition and attempted to start the flashing key light would switch off. So my assumption based on this is that the sensor is detecting the transponder in the key. This isn't to say that the immobiliser isn't causing the issue, however without knowing anything about the factory security system I don't really know how to test this further.

As a desperate attempt to fix the issue I thought maybe the issue is to do with the battery / connection, even though when the car cranks it always cranks very quickly and without any issues. I tested the battery for voltage and it is sitting around 12.4v when the car is off and I cleaned the terminals and clamps to remove any corrosion and then applied some battery spray to prevent future corrosion. After doing this the issue didn't occur for about a week and I thought maybe I had got lucky but then unfortunately it failed again.

Other thoughts I have had is that a failing relay is causing the issue, however despite having the wiring diagrams for the car I am unable to locate any relays that are part of the starter circuit. The diagrams I have are from the US service manual and do show a "Starter Interlock Relay" however I believe (and could be very wrong here) that the Aus model WRXs don't have this relay. From my reading online this relay and a switch on the clutch pedal form part of the starter circuit on the US WRXs which prevent the car from being started unless the clutch pedal is depressed, however I know that I can definitely start my car without the clutch pedal being depressed so I'm assuming that this switch and relay are not part of the Aus WRX starter circuit. As I said I could be completely wrong here and if this relay does exist in the Aus model would love to know where it is located so I could test it. There are many reports online from people in the US with WRXs having starting problems with pretty much exactly the same behavior and their issues have been to do with either the clutch safety switch or the starter interlock relay, but I don't think this applies to the Aus model.

I have pretty much run out of ideas of things to check or test, I would take the car to an auto electrician to diagnose however I can't see much point in doing this until I can get it to consistently fail, until then I doubt they would be able to do anything. Given the clock light is dimming when I attempt to start I assume the starter circuit is opening but something is stopping it from reaching the starter solenoid.

Batteries tend to fail when it's winter and cold. Reading the above, that's where I'd be headed. I see you've checked the voltage, but you can get a free battery check done at a lot of tyre places these days. Worth a look.

Bad/poor earth...

Is anyone able to help? Or has this issue been resolved? I too have an AUS MY06 WRX, and all of a sudden, the starter motor has given up, pretty much exactly as described by sawaad, but not so intermittent. I went to start it yesterday, thought is was weird it didn't crank until the third try.

It worked a few more times as usual, but now nothing. It doeskin matter how many times I try, no clicking, not spooling, just silence.

I have shorted the starter motor and solenoid, they both work, but what ever gives the solenoid a signal to engage isn't working.

I have also tested the ignition barrel, and one of the pins is switching 12v when turning the key.

So somewhere between the key barrel and the solenoid, something is not working.

Is anyone able to help pleaseeeee?

'Stortimus' is your fuel pump priming when you turn the key? And also, do you still have the factory Brant security system?

'Top-Deck' - Yes and Yes. I can also short out the solenoid signal wire with the ignition 'ON', and it will start.

Stortimus I had what sounds like the exact problem with my Brant system and have been told it is a common issue.
I would say that your Brant has a faulty/loose connection/bad soldering etc which is causing the intermittent non-response. The Brant controls 4 or 5 different parameters, and it is notorious for being poorly wired. Hence, when the connection is not made, the output does not fire at all.
In my case the fuel pump was the original issue...I thought it had died and bought a new one, only for the new one to also not prime at all. Got my local workshop to hardwire the pump with the ignition barrel and the problem completely disappeared.
A year later and I am having the exact same 'starter motor' issue...with it not cranking at all. Thought it was weird that the battery could have gone completely flat (in the 9 hours since driving it), only to find out that the starter motor is also controlled by the Brant.
Luckily I was able to disconnect and reconnect the Brant connector plug and this sorted the issue.
Long story short, get a local workshop to remove the Brant and replace with an aftermarket (if you want) immobiliser.
Until then, if you have the issue try disconnecting and reconnecting the Brant box. In the GC8 it sits under/behind the steering column in the foot well, and is the box with only black wires coming out of it.
Hope that helps!