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I have a 2000 chevy blazer with a 4.3 engine, It ran before…

Customer Question
I have a 2000...

I have a 2000 chevy blazer with a 4.3 engine, It ran before I replaced the crankshaft position sensor but rough, so I replaced it with a new one and now I don't have any spark or tachometer

Mechanic's Assistant: Does the vehicle stall at low speeds? Does it sputter?

It wont start at all

Mechanic's Assistant: Are you fixing your Blazer yourself? What have you tried so far?

I replaced the crankshaft position sensor that's what the obd code called for

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

It has 12 volts to all of the components

Submitted: 4 months ago.Category: Chevy
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3/7/2018
Chevy Mechanic: Dan, Technician replied 4 months ago
Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 25,969
Experience: Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Chevy Mechanic: Dan, Technician replied 4 months ago

It is possible new sensor is the problem, have you tried to put old one back in?

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Customer reply replied 4 months ago
the old one broke when i took it off i did however think it was a bad sensor from napa so i took it back and got one from autozone and its still not starting, i have checked voltage at the coil pack, and cps sensor both have 12 volts no spark
Chevy Mechanic: Dan, Technician replied 4 months ago

At sensor the pink wire should have power, purple wire should have ground, and yellow wire should have square wave voltage while trying to start. Let me know if all are good, thanks.

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Customer reply replied 4 months ago
pink wire has 12 volts, purple wire is a good ground, yellow wire stays at .25 volts
Chevy Mechanic: Dan, Technician replied 4 months ago

Yellow wire is a problem. Does it stay at .25v with key on or does key need to be in start position?

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Customer reply replied 4 months ago
it stays at .25 volt with trying to start it
Chevy Mechanic: Dan, Technician replied 4 months ago

I​ think sensor is problem putting out low voltage. It should be putting out closer to 3v-5v. I hate to suggest it but I would try a 3rd sensor as I don't see anything else that would cause problem. Let me know how it goes, thanks.

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Customer reply replied 4 months ago
will a crankshaft position sensor control spark
Chevy Mechanic: Dan, Technician replied 4 months ago

Yes, the crankshaft position sensor sends signal to the ignition module which controls spark. Ignition module uses crank signal to determine when to fire plugs.

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Customer reply replied 4 months ago
ok thanks
Chevy Mechanic: Dan, Technician replied 4 months ago

No problem, when you replace crank sensor also make sure there is not anything stuck in crank sensor hole. Let me know, thanks.

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Customer reply replied 4 months ago
i also heard that on these blazers their is a factory security system my security light flashes all the time would this play any role in my problem
Chevy Mechanic: Dan, Technician replied 4 months ago

No, that wouldn't disable spark. And there is nothing else that would cause the signal from crank sensor to be too low besides crank sensor, connection on yellow wire, or something in hole preventing crank sensor from getting a good reading.

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Customer reply replied 4 months ago
thanks
Chevy Mechanic: Dan, Technician replied 4 months ago

No problem, keep me updated. Thanks.

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Customer reply replied 4 months ago
I performed a better test on my crankshaft position sensor I spliced a wire into the output to the ecm and with the sensor plugged in my multimeter read .30 volts
Chevy Mechanic: Dan, Technician replied 4 months ago
That is still too low so I'd check connecter at crank sensor, make sure nothing is in crank sensor mounting hole, and if good try another crank sensor. Let me know how it goes
Thanks
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Chevy Mechanic: Dan, Technician replied 4 months ago

E​ver get problem figured out? Please do not forget to rate answer, thanks.

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Customer reply replied 4 months ago
You won't believe this the bolt holding the CPS sensor was too tight I backed it off a little and walla it runs I had the bolt to tight causing it to not sit right thanks for your help much appreciated
Chevy Mechanic: Dan, Technician replied 4 months ago

G​ood find, thanks for update.

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