03 Impala

Whats the deal with this note I read about it being a bad idea to install aftermarket keyless because the motors rest a 7 volts. In one breath it tells you that it has a single wire lock system, then tells you not to do it. What the Fuh. Is that for real?

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J Rilla

Owner/Installer

Its a bad idea to use the factory keyless to trigger an aftermarket piece because you usually use the lock motor wire. Its fine to add an aftermarket keyless system because you are using the lock trigger wire, and not the lock motor wire.

Ok I read it again and that makes sense, it was just written poorly since you can take it as upgrading from factory keyless to aftermarket keyless, or what they actually meant was only upgrading your factory keyless to an alarm triggered by the factory keyless.

Thanks

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J Rilla

Owner/Installer

Right, they're talking about a "keyless upgrade" alarm---it comes with no remotes of its own; it turns the factory keyless into a full alarm system.

The keyless upgrade alarms expect those three wires to rest at ground, and turn to a positive when the doors are locked/unlocked.

There is a way to add such an alarm to an Impala, if you should need to. Three relays are required. Go to each of the motor wires, and connect as follows:

87: fused, constant positive
87a: ground
30: motor input wire from car alarm
85: ground
86: motor wire from car's BCM

At rest, the motor wire's 7 volts isn't enough to trigger the BCM, so the alarm sees a ground as it expects to.

When the locks on the car are operated, the relay turns on, sending 12 volts positive to the car alarm as it expects.