No crank

Tiny
ANTONY CONNER
  • MEMBER
  • 2003 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Vehicle cranks over once in awhile but normally no crank and no power to fuel pump. Replaced relays, checked fuses. Relay for fuel pump not getting power signal from PCM to work. Also wont shift out of park. Just bought it and was told it was just a bad fuel pump.
Friday, August 16th, 2019 AT 1:32 PM

1 Reply

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

The fuel pump relay ground for the control side of the relay is provided by the vehicle's Power-train Control Module (PCM) or "computer". In the diagrams down below I have included a diagram of a typical 4 pin relay, the wiring diagrams for your vehicle's fuel pump circuit (all the wires are highlighted for you), and guides on how to find opens in an automotive electrical circuit and how to find unwanted resistance in an automotive electrical circuit using the voltage drop method, which is the preferred method, by far. Please go through these guides and check the fuel pump circuit for these conditions and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros
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Saturday, August 17th, 2019 AT 2:30 AM

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