Hello everyone,
I've recently come across a no crank no start on my '04 trailblazer. I have been reviewing several threads on here that go over this condition but I'm still stuck with no resolution. Below is what I have done to try and find the problem.
Tested the ignition switch with a test light and multi meter. Receiving 12 V battery power on all wires except for the yellow one when the key is in the accessory position ( key on ). When key is turned to crank/start the yellow wire receives 12V. From what I have been reading that is normal.
The instrument cluster acts completely normal during this, nothing looks at out of the ordinary to me when installing the key to turning to run.
Moved to the fuse block under the hood. checked for battery power on the ignition fuses. Power is available and the fuses are good ( checked with a multi meter and visual ). What I did find interesting is that the starter solenoid did not activate when I had a helper turn the key and I listen for the starter solenoid to click. Checked for power at the solenoid relay terminal 87 and 86. Both were receiving battery voltage. Figured the relay was bad, so I took some test leads and connected them to B+ and B- then connected the other end of the test leads B+ to pin 87 and B- to pin 85. You can here the relay change state so that checks out and is fine. Figured it may be a neutral safety switch that is giving me problems. Moving the gear selector into different positions and keeping my multi meter probed in to start relay socket 86, battery power would be present then taken away then back again as the selector was moved from park to drive then to neutral.
From what I can tell the starter relay isn't getting its ground reference from the PCM, to complete the circuit. I don't have a high dollar scan tool to perform and tests on the PCM to verify operation. So my question is, what tests can I perform on the PCM to verify operation of the PCM or is the PCM the problem and I should throw a new one on just to see what happens?
I've also jumped the starter motor contacts to verify it works and it cranks the engine over no problem.
Any help is greatly appreciated. I have attached a wiring diagram that I have been following to help assist with me trouble shooting.
I've recently come across a no crank no start on my '04 trailblazer. I have been reviewing several threads on here that go over this condition but I'm still stuck with no resolution. Below is what I have done to try and find the problem.
Tested the ignition switch with a test light and multi meter. Receiving 12 V battery power on all wires except for the yellow one when the key is in the accessory position ( key on ). When key is turned to crank/start the yellow wire receives 12V. From what I have been reading that is normal.
The instrument cluster acts completely normal during this, nothing looks at out of the ordinary to me when installing the key to turning to run.
Moved to the fuse block under the hood. checked for battery power on the ignition fuses. Power is available and the fuses are good ( checked with a multi meter and visual ). What I did find interesting is that the starter solenoid did not activate when I had a helper turn the key and I listen for the starter solenoid to click. Checked for power at the solenoid relay terminal 87 and 86. Both were receiving battery voltage. Figured the relay was bad, so I took some test leads and connected them to B+ and B- then connected the other end of the test leads B+ to pin 87 and B- to pin 85. You can here the relay change state so that checks out and is fine. Figured it may be a neutral safety switch that is giving me problems. Moving the gear selector into different positions and keeping my multi meter probed in to start relay socket 86, battery power would be present then taken away then back again as the selector was moved from park to drive then to neutral.
From what I can tell the starter relay isn't getting its ground reference from the PCM, to complete the circuit. I don't have a high dollar scan tool to perform and tests on the PCM to verify operation. So my question is, what tests can I perform on the PCM to verify operation of the PCM or is the PCM the problem and I should throw a new one on just to see what happens?
I've also jumped the starter motor contacts to verify it works and it cranks the engine over no problem.
Any help is greatly appreciated. I have attached a wiring diagram that I have been following to help assist with me trouble shooting.