I get RPM signal crazy and sometimes I don't get nothing

Hi,

If your RPM is erratic and your other gauges is giving weird readings you might have a faulty Instrument Panel Cluster (IPC). When I worked in the Chevrolet Dealership I replace them on a regular basis. I'm attaching wiring diagrams below for you to reference and use manual external gauge to check readings to diagnose.
Please let us know if this information is helpful for you and what fixed your problem.

Thank you
Joe T.

Hi,

It's possible the distributor shaft broke or stripped drive gear, And not distributing spark or the crank sensor is shorted or have an open circuit and also not sending a signal, You will need to run diagnostics on the Ignition system, I'm attaching links and wiring schematic and ignition diagnostic charts for checking resistance and voltage drops on the ignition system below to help you test these components, also included information on Engine cranks but won't start enhanced diagnostics, Please let us if this is helpful and what fixed your vehicle or if you need more information.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Thank you
Joe T.

If your not getting spark at the coil wire with a spark tester, You need to start checking primary voltage for the ignition system. Check the under hood fuse box ( Cell 10 20A ECM 1 fuse replace fuse if blown ), If the fuse is good, You need to check for 12 volts at the ignition coil connector, (Key on engine off), with a voltmeter check the pink wire to the black wire with white stripe for 12 volts, If you have 12 volts unplug the ignition coil check the resistance (Ohms) from the coil towler to the body of the coil, If you have any resistance at all replace the ignition coil, Next unplug the crank sensor check for 12 volts at the pink wire and black with white stripe for 12 volts if you don't have volts repair open wire, If you have 12 volts replace the crankshaft sensor, Next unplug the ignition module connector and check for 12 volts at the pink wire to the black wire with white stripe, (If you have 12 volts replace the ignition module), If you don't have 12 volts repair open wire, Refer to the wiring diagram it will you locate wires. Please let us know if this was helpful and if you need any more information.

Thank you
Joe T.

Happy to see you fixed it. Thank you for choosing 2CarPros, Let us know if you have any other vehicle repair concerns and we'll be happy to help you with information on fixing it.

Thanks again
Joe T.

You are welcome, DUFFDIVER is one of our newest experts, he is quickly shaping up to be one of our best!