"hotwire" fuel injectors?

[nuttin]

I have a 2009 Silverado V6 4.3 with the intermittent no crank, no start issue.
Have had to had it towed twice this month.
When it happens I can jump the starter relay and it will crank but not start.
I am thinking the passkey 3 theft deterrent on this model is not
sending a signal to the ecm to power the fuel injectors. My question is if there any way
to make the ecm turn on the fuel injectors? I just want to be able to get it to
the shop and avoid another towing hassle if possible.

[Blue Bowtie]

It's not that the injectors are not getting power, but that the PCM is not pulsing the injectors when the security system is not happy.

The BCM should have stored codes if there was a PassKey fault.

[777stickman]

How do you know the injectors are not firing? Can you hear the fuel pump run for a couple of seconds when the key is turned to "run"? If you can hear the pump run then what is the fuel pressure?

[nuttin]

Originally Posted by 777stickman

How do you know the injectors are not firing? Can you hear the fuel pump run for a couple of seconds when the key is turned to "run"? If you can hear the pump run then what is the fuel pressure?

I am not a mechanic but I do have some electronic experience. The way I understand the theft deterrent passkey 3 system is that if the key is correct it will send a signal to the module to turn on the starter and the fuel injectors. I was thinking that if I could locate the signal wire and "hotwire" it that the motor would start. I'm just looking for a quick and dirty way to get motor started to avoid towing.

[Blue Bowtie]

I'm not certain of the PK3 systems signal, but the older systems used a FM square wave sent to the PCM to enable cranking and injector operation. It's not simply applying power to a given input.

There is always this kind of solution: https://www.amazon.com/Gm-Passkey-3-.../dp/B0009SXOUG

[nuttin]

Originally Posted by Blue Bowtie

I'm not certain of the PK3 systems signal, but the older systems used a FM square wave sent to the PCM to enable cranking and injector operation. It's not simply applying power to a given input.

There is always this kind of solution: https://www.amazon.com/Gm-Passkey-3-.../dp/B0009SXOUG

Thanks for info. Have you ever used the 555 bypass interface? I am wondering if it bypasses the module that cuts off the injectors and starter or if it just allows you to use a key without a transponder in it.

[Blue Bowtie]

I've never needed to use one of those type aftermarket modules, but I have removed them from previous installations. Normally, with VATS/PassKey/Passlock issues it is easier to repair the problems. These bypass modules simply allow sending a signal to the PCM without a key present, allowing a remote start. This only eliminates the key RFID, the transponder ring (coil) at the ignition lock, and the wiring to/from the ignition lock and PK module.

The PassKey module is what sends a signal to the PCM to allow cranking and injector operation. It is likely that the module is not happy with the key signal, the PK module is damaged, or the wiring to the PCM is damaged. There is a very remote possibility that something happened in the PCM, but that is not very likely.

[nuttin]

Originally Posted by Blue Bowtie

I've never needed to use one of those type aftermarket modules, but I have removed them from previous installations. Normally, with VATS/PassKey/Passlock issues it is easier to repair the problems. These bypass modules simply allow sending a signal to the PCM without a key present, allowing a remote start. This only eliminates the key RFID, the transponder ring (coil) at the ignition lock, and the wiring to/from the ignition lock and PK module.

The PassKey module is what sends a signal to the PCM to allow cranking and injector operation. It is likely that the module is not happy with the key signal, the PK module is damaged, or the wiring to the PCM is damaged. There is a very remote possibility that something happened in the PCM, but that is not very likely.

Is the Passkey module the assembly on the steering column that the key goes into?
That signal coming out of there to PCM is what I was hoping I could "hotwire" to be able to get the truck started in an emergency.
Since there appears to be no power to the start relay and the injectors this is the reason I believe the passkey circuit is not working even though the security led does not light. Is there any other module that controls both the starter and injectors?

[nuttin]

Originally Posted by Blue Bowtie

I've never needed to use one of those type aftermarket modules, but I have removed them from previous installations. Normally, with VATS/PassKey/Passlock issues it is easier to repair the problems. These bypass modules simply allow sending a signal to the PCM without a key present, allowing a remote start. This only eliminates the key RFID, the transponder ring (coil) at the ignition lock, and the wiring to/from the ignition lock and PK module.

The PassKey module is what sends a signal to the PCM to allow cranking and injector operation. It is likely that the module is not happy with the key signal, the PK module is damaged, or the wiring to the PCM is damaged. There is a very remote possibility that something happened in the PCM, but that is not very likely.

Is the passkey module the assembly in the steering column that the key fits into?
That signal wire is what I was hoping I could "hotwire" to get the engine started in an emergency. When this trouble happens, the security led is not lit but it seems that the starter relay and the injectors are are not receiving a signal to turn on. Is there any other module that shuts down the starter and the fuel injectors?

[j cAT]

no security lamp on .. no crank you bypassed the starter relay to get eng to crank and no injector operation ..

possible a PCM connector failure. you live in a flood zone ? drive in deep water ? that can be the problem.

PCM grounds the injector coils .. 12volts is on all the injectors all the time..
possible a corroded fuse ... NEW GM has many electrical failures ... old GM not a problem with wiring/connector/electrical components.

post some of your work on the vehicle so you could get a fix...

[nuttin]

Originally Posted by j cAT

no security lamp on .. no crank you bypassed the starter relay to get eng to crank and no injector operation ..

possible a PCM connector failure. you live in a flood zone ? drive in deep water ? that can be the problem.

PCM grounds the injector coils .. 12volts is on all the injectors all the time..
possible a corroded fuse ... NEW GM has many electrical failures ... old GM not a problem with wiring/connector/electrical components.

post some of your work on the vehicle so you could get a fix...

no flood zone...My mechanic replaced ignition switch, 2 days later no crank no start.
He's thinking now of replacing under hood fuse printed circuit board.
If PCM supplies ground to injectors would it be possible to run a ground wire to injectors for emergency start?

[Blue Bowtie]

Grounding the injectors with a jumper wire would make them go static - Wide open with full fuel flow. It would probably flood in a matter of seconds. The PCM grounds the injectors individually with variable timing (pulse widths) to control the volume of fuel according to whatever conditions are present, considering RPM, throttle position, temperature, etc.

[nuttin]

Originally Posted by Blue Bowtie

Grounding the injectors with a jumper wire would make them go static - Wide open with full fuel flow. It would probably flood in a matter of seconds. The PCM grounds the injectors individually with variable timing (pulse widths) to control the volume of fuel according to whatever conditions are present, considering RPM, throttle position, temperature, etc.

Since the security light is not on, maybe the fuel injectors are not being shut down by the anti-theft system. If the starter relay is jumped shouldn't the motor start if the right key is used and the switch is turned to start or is there something else that would stop fuel injection?