Having previously disabled OnStar on a 2017 Colorado, I've been wanting to complete ever since acquiring my 2020 Tahoe and do not wish to get into a debate as to why.
In the Colorado, the 'black box' was behind the glovebox and contained three circuit cards and you had to do was remove the card attached to the OnStar antenna. I did, threw it in a static free bag, and never had an issue.
On this thread everyone is referring to a SIM card, and I envision a cell phone SIM card, not a circuit card...so kinda different IMO.
I haven't performed this yet cause I can't seem to find absolute detailed instructions, with pics, of exactly what needs to be done without all of the bells/whistles/lights that I do NOT wish to excite while possibly disabling the vehicle.
Can anyone please provide a solid link for this task?
i just deactivated onstar and removed the onstar modem from a 2023 silverado and a 2020 tahoe. the process for removing the modem is very similar in both cases, but the location of the vcim (vehicle communication interface module) is notably different in the 2 vehicles. i hope this information can save others time, so they don't have to remove tons of trim in their car hunting for their vcim.
in both cases, you should first use the existing working onstar system to "deactivate" the system, which nominally disables onstar. press the onstar button, speak to a customer service person, and ask them to fully disable the onstar system in the vehicle. this should take 5-10 minutes per vehicle.
since it's not possible to tell whether the system is actually deactivated, you now need to access the vcim and disconnect the onstar + cellular modem, which attaches to the corresponding antennas. note there is no sim card to speak of, and you must remove the entire modem to ensure the transceiver is not sending. i suspect it's possible to retain the use of the onboard cellular link if you simply disconnect the onstar antenna lead, but i don't care about this option and remove the entire modem.
it is safest to disconnect the battery while performing this work to minimize risk of zapping electrical components, e.g. the vcim. use a 10 mm socket to loosen the negative terminal clamp in the engine compartment.
for the 2023 silverado, the vcim is just above the gas pedal and can be accessed by removing a single 7 mm screw that holds the foot ac duct in place and removing the duct segment. this screw is oriented backwards and is pretty annoying to remove. there are 2 black plastic retaining clips that need to be pushed to the side before you slide the vcim down. the vcim has 2 antenna leads, one brown and one purple, and a data connection. disconnect the cables that connect to the vcim. you will need to squeeze the antenna lead connectors while using a larger flat blade screwdriver or similar to apply upwards/outwards pressue on the connector in a few places by twisting it between the connector and the module. be gentle while doing this to avoid damaging the modem and the leads. once the vcim is disconnected, remove the 2 x T8 screws on the side of the unit near the antenna connectors and then slide the modem outwards, possibly using a flat blade screwdriver to get it started. store the modem and 2 screws somewhere in case you want to reconnect the modem in the future.
most of what i said applies to the 2020 tahoe as well, but the vcim is located above the glove box. the location of the vcim may vary depending on your trim kit, but i am simply trying to manage expectations here since i have not done this on any vehicles besides my own. empty your glove box, slide the clip that holds the retaining cable to the box out, press the sides of the glove box inwards, and rotate the glove box downwards. there is a panel now accessible that has 6 x T15 screws securing it. remove these screws and the panel to expose the vcim above it. similar to the silverado, press 2 black retaining clips and pull the vcim downwards. disconnect the cables per the process i described for the silverado. undo 4 x T10 screws on the disconnected vcim to expose the mainboard and the card for the modem. remove the modem card by undoing 3 x T10 screws, reassemble the vcim box without the modem, and reconnect the data cables.
my motivation for doing this work is that i'm a computer security expert who hates being tracked online and in person. it is surprising that information about the location of the vcim is so hard to come by. i spent roughly 4 hrs locating and removing the vcim in the silverado and 8-10 hrs for the tahoe (i removed all trim and center console to find the vcim). i hope this information allows others with the same or similar vehicles to avoid wasting hours of their life pulling off trim and looking for the vcim in their vehicles. with these instructions in hand, it should be possible to perform this process in roughly 1-2 hrs per vehicle.
since i have no use for it, i'm interested in fully disabling the wifi access point in the vehicle to reduce its attack surface. i would appreciate any pointers on how to go about doing this.
