# Knock Sensor / Possible Short / Starter Circuit Issues



## Rash_808 (Mar 28, 2020)

Hi New member never posted before so hopefully this is the right location.

*Car: *2012 Chevy Cruze 1.4L

*Background:*
Was changing out the knock sensor (Check engine light on, scanned and got knock sensor code, just decided to replace sensor never checked power in circuit or anything) and as a self certified home mechanic of course I messed something up.
Forgot to disconnect the battery when changing the sensor which led to a temporary short from the knock sensor to bolt and socket enough that it sparked and heated up the socket (No shock to myself, knock sensor was plugged in to use the cord to help position the sensor when bolting). This occurred when attempting to bolt on the sensor. The way the knock sensor is positioned the socket was probably touching the starter motor and engine block when it shorted
After the short I disconnected the battery, finished installing the new sensor etc.
Only other work performed at the time was an oil change, All work was done in the same time period, Car never had starting issues before, No problem finding the knock sensor so didn't unplug anything randomly.

*Problem:*
When attempting to start the car all lights will turn on but the engine won't turn over or even attempt to turn over.
Only sound heard is a buzz and pop/click sound which I am assuming is some electric pump in the transmission (Sound is coming from there) not sure though as not too familiar with these cars.

*Things I have checked:*
Battery was low after attempting to start, recharged and still same issue.
Checked some fuses briefly in the starting circuit (5 and 69 I believe).
Disconnected knock sensor and attempted to start, still same issue.

*Looking for feedback on:*
Any idea of what the issue is / what to look at next.
More advanced circuit diagrams / list of fuses to check in starter and knock sensor circuits.
Any guidance on working through electrical issues as I don't have much experience with them or newer cars.
Links to any helpful past threads.

Thanks for the help in advance, working 12 hour shifts from home not really an urgent issue will respond when I can, hopefully I didn't fry the ECU lol.


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## Ricardowelch (Sep 18, 2019)

Rash_808 said:


> Hi New member never posted before so hopefully this is the right location.
> 
> *Car: *2012 Chevy Cruze 1.4L
> 
> ...


sorry to hear your issue. I think it could be problem with starter and battery, replace if it can solve this issue or take it to dealer to help you to figure out the issue together. Good luck.


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## Blasirl (Mar 31, 2015)

Rash_808 said:


> Hi New member never posted before so hopefully this is the right location.
> 
> *Car: *2012 Chevy Cruze 1.4L
> 
> ...


Any codes?


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## Rash_808 (Mar 28, 2020)

I finally got some time to trouble shoot.

Figured out the short occurred due to my socket extension touching the exposed terminal for the main power line on the starter.
When I was bolting in the knock sensor it shorted through my wrench to the block.
The big 250A fuse on the battery is what blew and prevented starting.

Pretty crazy


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## snowwy66 (Nov 5, 2017)

If it looks possible. ALWAYS disconnect the battery.

You can do some serious damage to the car components. 

I heard one guy lost his finger changing a starter motor on a 70s car. Wedding ring shorted the starter cable to engine ground.


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