2005 STS won't start again

hiljak · #1 (**permalink**) 05-10-08, 11:13 PM

Well,

I've had an ongoing problem with my 05 STS not starting. This happened about a month ago and I baught a new battery which seemed to fix the issue. The next morning, car won't start again. Swapped the battery again and it worked.

Eveything seemed fine for a day or two, then the car does it again (hit the start button and everything goes black except for the orange engine light for 20 seconds, then dash lights back up). I fiddled with the battery connections (unscrewed then screwed them back in) and after a few more presses of the button, the car started. This lead me to believe that maybe the start button was worn and not making the connection.

I swapped the start button and everyhting was fine for about a month. Now, same thing happening. I don't think its the battery because the car won't crank with a craftsman jumper charger connected either (and battery reads like 13 volts on the dash).

Here's what I've tried:

changed the starter switch.
swapped the starter relay for another identical relay in the fuse panel.
swapped the "crank/start" relay with another identical
unhooked the boly which connects the ground cable to the strut tower and cleaned.

What else can I do here? I'm going to swap the battery under warranty tomorrow. Any ideas of how to trouboeshoot this?

hiljak · #2 (**permalink**) 05-12-08, 12:43 AM

Battery was tested and is fine.

I checked the starter power wire and was seeing 12.4 volts. The purple wire feeding the starter solenoid was displaying .08 volts with no change when hitting the start button or with the remote start.

Decided to remove the starter relay and jump the points manually with a jumper wire; this made the starter turn over immediately. I put the relay back in and the car fired right up.

I'm not sure what this is telling me. It would seem the relay was bad but I tried another good relay earlier and the starter still didn't engage (and the relay is working fine now). I'm thinking either
1. the purple wire that feeds the starter solenoid may have an intermittent short or loose connection somewhere between the under-hood fuse panel (from the starter relay) and the starter solenoid
2. there is a short or loose connection somewhere between the start button and the trigger point for the starter relay (but maybe this is controlled with GMLAN command??).

What I don't know is why manually jumping the relay would make the symptom disapear? Any ideas?

justgreat · #3 (**permalink**) 05-12-08, 11:18 AM

okay...i'll jump in...you obviously are well into the mechanical/electrical trouble shooting arena. i would step back and use the KISS principal (keep it simple stupid....no slight intended). you need the fob in close proxcimity to the car and i wonder if the problem might be a weak battery in the fob....how about trying another fob or checking the volage of the fob battery.

jackg
06 sts6

jglassco · #4 (**permalink**) 11-09-08, 08:52 PM

any resolution to this problem guys? my sts wont start either and it sounds exactly like your situation....

hiljak · #5 (**permalink**) 11-10-08, 12:09 PM

It was resolved by swapping the starter. The started had a bad spot in one of the brushes which was causing the issues. It was sort of like russian roulette, if the starter happened to land on the bad spot when I shut off the car, it wouldnt start back up.

Here's what you should do (and what I should have done). Get a small buld and socket, 12v (like say one from an old turn signal, brake light, etc..) and hook the positive lead from this light up to the puprple wire going into the starter solenoid on the starter (fat purple wire). This wire gets the 12v pule when you hit the start button. Hook the gound lead from the buld up to ground and run the actual buld so it come out from behind the hood (in between the hood and windshield) so you can see it easily from inside the car. This bulb will light everytime you hit the start button. What this will do is show you that everything up to the actual starter is working. Once the car won't start, if the bulb lights but no started action, you know 100% for sure its the starter. If the bulb doesn't light, you know its either the starter switch button, starter relay, or a short in the wiring (unlikely).

Good luck dude