Hey all, my 05 STi has a seemingly random intermittent no start issue. I originally thought it was the battery or starter, but I have replaced both and run all new and upsized cable.

Thinking now that it's something with the immobilizer. The cycle the key 3 times reset doesn't seem to affect it. It has full power, but will not crank when this occurs. I was wondering if a new key with a new chip could fix it? I don't know if the chips can become corrupted like a thumb drive? Or if I need a whole new ignition cylinder, which seem to be rather difficult to find.

Any help would be greatly appreciated, it's very nearly left me stranded several times now.

 

Thanks in advance.

Do you have power to the small wire on the starter? Start there and work your way back. It could be the ignition switch, not the part where key goes in, but the electrical connection.

Does the starter-motor 'click' once when you try to start?

If so, it could be worn contacts in the starter-solenoid.

on my 05 OB the starter would get stuck on a dead spot. what I did was carry a length of 2x3" that I would thread down from the top and use to tap the starter. Worked every time.

you might try 'popping' the clutch pedal 2-3 times next time it fails. maybe the safety switch on it is failing. Or the one on the brake pedal?

@forester2002sThere is an audible click when they key is turned, however the solenoid was replaced along with the starter.

@1 Lucky Texan Is there any way to delete or bypass the clutch safety switch? I certainly don't need it.

4 hours ago, SiriusBlack said:

@forester2002sThere is an audible click when they key is turned, however the solenoid was replaced along with the starter.

I missed that in your original post. So it's new starter, and it 'clicks'. That suggests that it is trying to connect 12V from the battery to the starter. Try measuring the voltage at the 12V terminal (the large heavy-duty cable) on the outside of the starter. There should be 12V here at all times.

Edited November 9, 20232 yr by forester2002s
Corrected statement about 12V at the starter.

I have now jumpered both clutch switches. We'll see if that fixes it.

1 hour ago, SiriusBlack said:

I have now jumpered both clutch switches. We'll see if that fixes it.

If the starter-solenoid 'clicks' when you try to start, that means that the clutch-pedal has been depressed and is working as it should.

It could be time for the old stater relay mod that was done back in the day. 

Add a 30amp horn relay triggered by the starter wire to give the starter solenoid a full 12v kick to get it going. 

If that doesn’t work then your starter motor is most likely toast or on the way to being toasted. 

Cheers 

Bennie

8 hours ago, el_freddo said:

It could be time for the old stater relay mod that was done back in the day. 

Add a 30amp horn relay triggered by the starter wire to give the starter solenoid a full 12v kick to get it going. 

If that doesn’t work then your starter motor is most likely toast or on the way to being toasted. 

Cheers 

Bennie

For it to be toast, it would of had to have been out of the box. It's a brand new starter and solenoid. Which is entirely possible.

On 11/11/2023 at 1:18 PM, SiriusBlack said:

I have now jumpered both clutch switches. We'll see if that fixes it.

You just need to jumper the clutch switch that goes off on full depress.  The clutch switch on slight press is the one that disengages cruise control, doesn't have anything to do with the starter.  FYI

@nvu Yeah I figured that out after I did it XD.

Sorry for the late update on this Issue. I'm pretty sure the contacts in the ignition switch are bad. I installed a push button that gives the starter a direct 12V upon press. So when the issue pops up, just key on and Push button.