does Onstar have an external antenna?

Discussion in 'Audio, Video & Gadget Tech' started by sfarris, May 16, 2009.

  1. sfarris

    sfarris Member


    I pulled my Onstar this week to install a Bluestar unit and use bluetooth on my cell phone. I noticed two antenna connections in the back of the Onstar. Does the Onstar have an external antenna? Better yet, does anyone have a wiring diagram to an Onstar unit? I am installing a cell amp or at least an external antenna for my cell phone to get signal when I am out in the boonies.

    thanks in advance.
  2. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    There is an Onstar external antennae on top of the truck over the driver's head, it should have a little stubby antennae that screws off of there. I have never messed with Onstar before but I know there are wires run up under the driver's side headliner, I saw them when I was doing a wiring project a few days ago. What I was going to ask is are you sure the antennae is the problem? I just had my Onstar upgraded last year and they replaced the VCIM (vehicle communication interface module) This is essentially the brains of Onstar and the cellular pickup in the truck, I have some diagrams for that and the wiring for under the headliner but I'll tell you right now that box is BURIED underneath the dash!
  3. sfarris

    sfarris Member

    I would like to see wiring diagrams

    Thanks in advance. I am not having any problems with Onstar- I plugged in a Bluestar module to use bluetooth phone with it, and in effect disabled the Onstar. So, if it has an external antenna, I can utilize that to run through my Cell Amp rather than mounting another Antenna on the side of my truck.

    Thanks again.
  4. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    I don't know if I'd advise that. The antenna is probably not providing enough gain to make a difference, it may be on the wrong band to help you (ie, it's running off of GSM when you need CDMA which is on a different radio band), and if you're using an external/internal antenna setup like a wilson booster system, the 2 antennas need to be several feet from each other to keep oscillations from occuring (the amp backfeeding into itself). All of these would cause it not to work or possibly cause the cell amp to break.
  5. sfarris

    sfarris Member

    Dunno about that

    AS I understand it, an antenna is just a collector- it is not often band specific. Most cell antennas seem to be tuned for both CDMA and GSM. Since Onstar works with Verizon, it is likely CDMA, so I am guessing it will work with my GSM. If not, I will change the antenna! I think the Amp is the bigger deal.

    I don't know what you mean about 2 antennas- I am going to hijack the Onstar antenna to avoid mounting another antenna.

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