Trailblazer 06 tried to start itself

Beeper

Original poster
Member
Mar 14, 2018
5
Pa
Hope someone can help me out troubleshooting this issue. First off my starter has been turning very slowly so yesterday I installed a new starter. Now it cranks fast and starts great everytime. My issue came this morning when my wife stepped out to get in her car and go to work. I had cleaned her car off for her and started it so when she stepped outside she asked if I had started my TB also. I said no and she said you better come listen to it. As I stepped outside I could her the engine cranking and getting slower as I walked towards it. Mind you there is not a key in the ignition and the vehicle has been parked for the last 16 hours. I hit the key fob to unlock the door and it did not work. I opened the door with the key, put a key in the ignition and turned to start and the engine started fine and the starter did disengage. Turned ignition off and everything stopped. Everything has been fine again for the last 3 hours. Starts strong and key fob works again. I did pop hood to check starter connections and they all still look good. There is not a remote starter.

Info that may be of use but maybe not. After hooking battery neg back up after installing new starter, the window/lock controls would not work on drivers door. They would work on passenger door. By the time I drove 20 feet the drivers controls were working again. A clump of snow was dropped on my drivers arm rest prior to starter change out so I just assumed it shorted the switches..........until now. This may be a completely different issue. I just didn't want anyone to say "why didn't you tell us that to begin with...." later on.
2006 trailblazer 4x4 4.2 any thoughts or help would be appreciated. Next troubleshooting steps to take?
 
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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
There is a recall for the door switch module for an issue with them catching on fire when shorted by water. Has it been replaced? with the updated one?

For the starting, maybe the door module could have been sending garbage data to the PCM to start. No probable but possible. Another possibility is a defective relay. I'd replace it or swap it with another one from another circuit just in case. Lastly, electrical weirdness has been attributed to the ignition switch getting flaky.
 
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Beeper

Original poster
Member
Mar 14, 2018
5
Pa
Shame on me! I have the recall, 2 in fact, sitting on my desk for months but never got them done. I guess I'll have to make time to make it happen if for no other reason to eliminate the possibility. That could possibly tie into the FOB not working at that exact same time also couldn't it?
I'll also swap the relays today to see if the problem moves with the relay. I thought about a relay issue but have never seen one switch on when it fails. Always gets stuck off, stuck on or fails to off but never fail to on. Worth a try though. I'll hold off on ignition switch until it happens again after the previous things are tested. Thank you for your help. I appreciate it! I'll keep you posted.
 

mrrsm

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Oct 22, 2015
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If this vehicle gets parked inside of a Closed Garage... Then you should Dis-Connect the Battery Negative Ground Cable. I have seen too many people die from Carbon Monoxide Poisoning by accident ...and on purpose... not to make mention of this matter.
 
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Sparky

Member
Dec 4, 2011
12,927
Dirt on the data bus can cause weird things. When my transfer case control module went bad on my old 02 Trailblazer the garbage on the data bus would randomly turn my radio off until the next key cycle. Of all things I never would have guessed that.
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
Definitely take care of the recalls. Until my door switch was changed out I had some weird electrical stuff happen. One of them was the drivers door would randomly lock while it was running and in neutral.
 

Beeper

Original poster
Member
Mar 14, 2018
5
Pa
Update: When the starter motor wire and the coil wire were put back on the new starter the tabs ended up facing each other. Although I couldn't see if they were touching due to the position of everything I do imagine they were extremely close. Possible a bit of ice/water shorted the 2 activating the coil?

The ring terminals have now been re-positioned to eliminate that possibility.
MRRSM: I do not garage this vehicle but thanks for the concern. I do appreciate it!

Another question......under normal conditions would the FOB unlock the doors while trying to start? I know starting the vehicle usually causes many systems to not function while cranking. Lights dim, radio stops etc etc. Just wondering I'll have to try this although the vehicle starts quickly so will have a hard time recreating.
 
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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
AFAIK no. Only time it should lock/unlock is with the shifter going out/in to Park.
 

Redbeard

Member
Jan 26, 2013
3,466
fwiw: My '04 two wheel drive "self locks" at about 10 mph and will unlock when shifting out of drive into park.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
That is an option on those with a DIC to either have it lock by speed or by the shifter.
 
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Beeper

Original poster
Member
Mar 14, 2018
5
Pa
I guess I should rephrase my question. While I was cranking the engine would I be able to unlock/lock the doors using the remote keyfob?

Mooseman: Scheduled the door safety switch recall with the dealer today. Thanks all for the concern that motivated me to get it done.
 

budwich

Member
Jun 16, 2013
2,027
kanata
you can do your "starter cranking, nothing operates test", pull the fuel pump relay and crank away (may take one or two tries to clear existing pressure / fuel).... but after that you can crank for a bit (don't burn out your starter), and check what ever "button function" you want to see what will happen... go from there. I would suspect nothing would operate although I haven't personally checked this. If you want to do the "circuit analysis" instead, go thru the powering schematics and check what power points get power in "start" as opposed to "run".... its probably few to none.
 

Beeper

Original poster
Member
Mar 14, 2018
5
Pa
Thanks. I will pull the pump relay to test. I only need 2-3 seconds. My new starter turns so fast the engine starts near immediately. Can you tell me where I can find the powering schematics?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Check my signature
 

Reprise

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Supporting Donor
Member
Jul 22, 2015
2,724
No, no, no... all of you have it wrong. The OP needs a Catholic priest, as the truck is possessed. :yikes: :biggrin:
(and you thought the green 'puke' coming from it was coolant... wrong!) :puke:
 

B33p3r

Member
Nov 2, 2013
26
Well it's been three days since my TB tried to start itself with no more incidents. I'm going to call it fixed. I'll name the cause as self induced by not paying attention to the direction of the tabs on the ring terminals when removing the wires. Actually didn't know they were there. Starter being in a tough spot the wires were removed mostly by feel so never knew the original direction of tabs. I still can't say for sure but I do know the tabs are no longer facing each other. Thank you all for the help and Knowledge! It is very much appreciated.
 
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