Using OEM switches as universal ones aka not hooking up to BCM.

v10runner · May 1, 2019

So, I already asked a somewhat similar question involving the same install but this is focused on another subject.

Is it possible to use OEM switches of this gen truck but wired as if they were universal mainly referring to bypassing/not wiring it to the BCM? I was thinking of using the OEM switch for the mirror control of an LT/LTZ trim for an '08 Silverado WT, is this possible?, With all the deal about everything needing to go to the BCM, can the switch function properly without that?, let's say just hook up 12v+, ground, the mirror glass' wires and will it work? Would this be possible with the 2014+ switch, putting aside the whole wiring harness, running it to the BCM deal, just using the switches as if they were universal (12v+,gnd,load)?

Thanks.

sefiroxx · May 1, 2019

Switches are switches - on off

Bcm etc control the load by switching the 12v power or the ground. It also sends out sensor signals (typically 5v).

If you bypass the control side and leave the sensor signal in place, then the bcm may throw a code as it thinks the load is in a specific state while the sensor signal suggests otherwise.

v10runner · May 2, 2019

1 hour ago, sefiroxx said:

If you bypass the control side and leave the sensor signal in place, then the bcm may throw a code as it thinks the load is in a specific state while the sensor signal suggests otherwise.

But in this case the BCM of this truck isn't equipped or programmed for the parts I'm adding so it shouldn't even detect anything wrong with it and I'm not connecting or disconnecting anything to or from the BCM, the main issue here is if I use the OEM style switches that typically run through the BCM, without connecting them to the BCM, will the switches work?, Is that connection from the switch to the BCM essential for the switch to work?

Universal switches typically use 12v+, ground, and load or loads or whatever for them to function, OEM style switches use those and BCM connections and/or 'reference' connections and I don't know what else to function. Will an OEM switch, let's say ignoring the BCM connections and/or reference connections, function correctly like an universal switch? On, off without BCM signals or references? I hope I'm making sense.

sefiroxx · May 2, 2019

Vast majority of the switches are NOP (normally open) momentary (spring back). Press them, they connect two wires.

Some are rocker, essentially connecting either two pairs or allowing two wires to connect to one alternatively.

A very small minority are pentometer in nature, supplying a varying resistance to the various connections.

As long as the switch is completely disconnected from all other circuits, then it can be used per specification.

Specification sets the amount of current (amps) that the switch can control. Ie, controls a low amp signal to a relay that turns on a 10A circuit.