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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16122
Experience:  15 years GM master tech
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2009 chevy trailblazer, po 335, po 651, co700. Lost power on

Customer Question

2009 chevy trailblazer, po 335, po 651, co700.
Lost power on drive home from work, engine light and reduced power lights came on, rpm gauge went dead.
Replaced crank senor, (didn't preform re-learn), restarted car, same rough idle, reduced power. next morning car wouldn't start (was going to take to shop).
Would not preforming learn cause this ? or bad crank senor maybe ? or possible not properly clipped together ?
Submitted: 4 months ago.
Category: Chevy
Expert:  Gary replied 4 months ago.

Welcome! My name is ***** ***** I will do my best to assist you with this problem.Ask me about added features such as phone contact anytime if you wish !

Expert:  Gary replied 4 months ago.

if you clear the codes and crank it over what code will reset first ?

Customer: replied 4 months ago.
po651, could crank sensor not being properly plugged in cause this ? i had a hell of a time getting the plug back on it..
Expert:  Gary replied 4 months ago.

yes it could be

as the 651 code is saying on a shared 5 volts reference that crank sensor and throttle body uses is showing more than 5 volts

if you unplug the crank sensor and clear the codes and crank it over will the 651 still set ?

Customer: replied 4 months ago.
ok, did that, still get 651. only 651 now.
Expert:  Gary replied 4 months ago.

ok that 651 is again a code set because of the shared 5 volts reference to the crank sensor or throttle body or gas pedal or secondary air pump is shorted or one of those is causing to much power down the signal shared 5 volts

with the crank sensor unplugged and it still setting the code if the wiring looks good to the crank sensor then unplug the throttle body connector will the 651 go away with that unplugged ?

Customer: replied 4 months ago.
Do i leave crank senor unplugged or plug it back in ? before doing test with throttle body unplugged ?
Expert:  Gary replied 4 months ago.

unplugged is fine

Customer: replied 4 months ago.
stil 651 with both senors unplugged.
Expert:  Gary replied 4 months ago.

ok unplug the gas pedal connector and if it still shows that code then unplug the secondary air pump

Customer: replied 4 months ago.
ok. same with gas pedal, first code with secondary air pump unplugged is 418.
Expert:  Gary replied 4 months ago.

with all 4 unplugged will the 651 reset ?

Customer: replied 4 months ago.
no, cleared again. 651 and 2127 came up this time.
Expert:  Gary replied 4 months ago.

with those all unplugged and that code setting one of those wires to each device shorted causing the code and this issue

if the 5 volt wires are shorted this will happen

Customer: replied 4 months ago.
basically some where there is a broken wire ?
Expert:  Gary replied 4 months ago.

or shorted to power or ground or a bad computer

a muti meter is needed next to start to test the 5 volt reference wiring

most shops can nail this down within an hour or so of testing

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Customer: replied 4 months ago.
A short in this 5 volt system would cause the whole system (curcuit) to not work ?
i do have a multi meter