Remote start options for 2005 Envoy

[gmcman]

I've searched the site and many of the threads are around 5 years old. So with that being said, does anyone have recommendations for a remote start system on a 05 Envoy with Bose if that matters.

Hoping to stay under $200 but not a deal breaker. I remember some manufacturers would not sell to an end-user for DIY but I assume there are others that are DIY.

I did see this video and that system looks pretty straightforward and would be all the owner needs, so something similar is what he's looking for.

All input appreciated.

 

[TJBaker57]

Interesting indeed. This will sound a bit odd but I will consider getting one of these for the purpose of investigating the serial data exchange.

Quick note about the names of the wires he taps: In our wiring diagrams there is no "primary ignition" or "ignition 2". They are called Ignition 0 and Ignition 1.

Since they apparently never tap into the Passlock wiring I expect they must be learning the current fuel continue password etc. during the startup programming of the "iData module".

Then they likely spoof the message exchange from the BCM & PCM about "fuel continue password" and so on.

The BCM should still see the lack of a proper Passlock sensor return signal since the key has not been turned.

I have assisted others online who developed issues with the Passlock system later on and some of these folks had that iData module.

The most recent one had an issue where the remote would start the engine but the normal start with the key failed. Such a problem likely would have happened without the remote start system anyway but having the remote just added another level of diagnostic difficulty.

This comes about because if a security relearn is done for whatever reason now the iData module doesn't know the new passwords etc. generated during the security relearn.

 

[gmcman]

I thought some of these remote start systems required a spare key tucked away somewhere. Would that work on the GMT360 or does it need to be in the lock cylinder?

 

[TJBaker57]

I thought some of these remote start systems required a spare key tucked away somewhere. Would that work on the GMT360 or does it need to be in the lock cylinder?

I'm not sure about having or needing a spare key somewhere.

The GMT360/370 Passlock system does not have anything special in the key itself. No chip, no transponder, nothing but a plain metal 10-cut GM key.

So there is no need to have an original key anywhere near the truck, except for the purpose of turning the ignition lock cylinder.

I understand that the Saab variant and Canadian models are different, I am talking of models made for the US market.

The GM factory Passlock system requires that the lock cylinder be turned. In the rotating cylinder is a small magnet that activates the Passlock sensor inside the lock cylinder housing. Seen here with the yellow, orange/black, and red/white wires.



Inside that sensor is a resistance that is used to drop a nominal 5 volt circuit from the BCM to a lower voltage. The resistance varies between vehicles.

If the voltage returned to the BCM by the Passlock sensor does not match the voltage the BCM has memorized for the vehicle then the BCM tells the PCM to not start the engine.

That said, knowing precisely how the system works I could bypass it with the proper resitance amd perhaps a small relay to switch the resistor into the circuit at the proper time.

And in the case of this remote start iData module I believe they are likely spoofing the messages that the BCM would be sending to the PCM allowing the PCM to start the engine.

This is of course my own guess based on my own recording and studying of these security messages seen on my own 2002 4.2 TrailBlazer.