I need Instalation advice I cannot wire the WPI with the (Red wire) with my Gmos-04 harness , the wpi frys my gmos04. Anybody got any ideas where i can get an alternate power source besides the red wire coming from the harness. Thanks
Depending on the year of your GM vehicle, there should be a bundle of blunt cut wires somewhere below and to the left the head unit. Following is a quote out of the GM electrical manual for my 08 Silverado 2500HD:
Installation Instructions —
12 Volt Accessory Power Supply
1. Disconnect the battery negative (-) cable at the battery. The
negative (-) battery cable must be disconnected before the
positive wiring lead is connected to the power accessory.
2. Locate the power supply harness under the instrument panel
near the center of the vehicle. The wire bundle consists of six
blunt cut wires, two red/white (battery hot), two black (ground),
one light green (Ign hot) and one light blue (Ign hot).
3. Remove the tape to release the wire bundles from the
power supply harness.
4. The IGN A and IGN B wires have voltage supplied and are
HOT when the ignition is turned to ACC, RUN or RAP
(Retained Accessory Power).
The BAT A and BAT B wires have direct voltage supplied
and are HOT at all times.
The combined electrical load of IGN A and BAT A must not
exceed 21 amps (250 watts). Additionally, the combined
electrical load of IGN B and BAT B must not exceed 21 amps
(250 watts). The combined electrical load of all circuits must not
exceed 42 amps (500 watts).
5. Prepare the wires that are to be used to connect the power
accessory. Do not remove the unused wires. Tape unused wires
back in their original position under the instrument panel.
6. Complete the wiring installation of the customer added
accessory with additional wire required for the specific
electrical accessory power connection. The wire gage,
12 gage (3.0 mm²), should be the same as the wiring of the
installed harness.
I recommend using these wires for any of the power needs for aftermarket HUs and related accessories. I had used an OnStar retention module for a while because 1) I thought I'd use OnStar and 2) it had the necessary wires for the assorted input wires of the HU harness (reverse, vss, parking brake - see ground, 12v, acc, ground). After the module blew, which didn't take long, I found all of the wiring points in the electrical manual. I never missed OnStar and I certainly didn't miss the chimes. I usually have my music, Rush, Hannity and/or Levin turned up too high to hear the turn signal anyway. In short, if you don't use OnStar, there's no reason at all to keep replacing those fragile POS retention modules.