Installation Instructions -- Emergency Vehicle Roof Panel Lamp

Wiring to the accessory can be done by either directly connecting the wire in the roof to the accessory (Option  A) or by using Wiring Harness Package part number 12150250 obtained from GM Service Parts (Option  B).

1. Disconnect the negative (-) battery cable at the battery.
2. Make the electrical connections using either option  A or option  B.

Notice: Pulling the wiring harness through a panel hole that has sharp edges may cause damage to the wire and/or wire insulation. Remove sharp edges from the panel hole before pulling the wire through it.

Option A: Roof Wires Directly to Accessory

1. Drill a 3/8 inch to 1/2 inch (10 to 13 mm) hole in the outer roof panel in the area shown in the illustration. The hole should only go through the outer panel. Remove all sharp edges from the drilled hole.
2. Pull out the wiring harness being careful to avoid scraping the insulation on the edge of the hole.
3. Extend the wiring harness to the accessory.
4. Connect the BROWN wire to the accessory hot terminal.
5. Connect the BLACK wire to the accessory ground terminal.
6. Cover the hole in the roof with a durable sealant such as silicone rubber sealer.

Notice: If you leave your radio or other accessories on during the jump starting procedure, they could be damaged. The repairs would not be covered by your warranty. Always turn off your radio and other accessories when jump starting your vehicle.

Option B: Use Wiring Harness Package 12150250. Obtain from GM Service Parts through the GM Dealership

1. Drill a 1.25  inch (32 mm) hole in the outer roof panel in the area shown. The hole should only go through the outer panel. Remove all sharp edges from the drilled hole.
2. Pull out the wiring harness being careful to avoid scraping the insulation on the edge of the hole.
3. Cut the wire to length. Install terminals to wire ends and insert into the connector. The BROWN wire goes in cavity A and the BLACK wire in cavity B. Push in the secondary lock to retain the wires.
4. Attach the harness assembly from the package to the accessory. Cover with the supplied conduit for added protection. Connect the ORANGE wire to the accessory hot terminal and the BLACK wire to the ground.
5. Complete the connection from the roof harness to the extension harness. Cover the mated connector with the supplied foam. Push the foam covered connection and excess wire through the roof panel hole.

Restoring Power

1. Be sure that the auxiliary lamp switch is OFF.
2. Vacate the vehicle and reconnect the battery cable.
3. Turn the auxiliary lamp switch on. The accessory should now be working. If it is not working, check the connections.
4. After ensuring that the accessory is working properly, install the grommet in the hole. Seal with silicone sealer to prevent water leakage.

Notice: Overloading the vehicle's electrical system may damage your vehicle's accessories. Do not overload the vehicle's system by having unnecessary accessories on at the same time.

1. Harness Assembly

2. Grommet (Roof)

3. Harness Connector, Secondary Lock and Terminal

4. Foam Insulator (Adhesive-Backed)

5. Vehicle Outer Roof Panel

Maintenance

The circuit is fed from the # 2 post on the underhood electrical center and protected by the fuse labeled "# 2 Post" located in the electrical center. Always replace the fuse with a 30 amp maxi-fuse.

Notice: Before modifying or adding any wiring, be sure that it will work properly with your vehicle's wiring system. Because there are so many modifications that can be made for many different bodies and accessories, GM cannot take responsibility for any changes made. Such changes may not be covered by your GM Warranty. Have the work done by an experienced electrical technician.

Installation Instructions -- 12 Volt Accessory Power Supply

1. Disconnect the negative (-) battery 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.
7. The ignition must be turned to OFF or ACC prior to attaching the cables to the battery, or serious damage to the Vehicle Control Module (VCM) may result.

The windshield wiper switch and the radio must be turned off before attaching cables to the battery.

8. Reconnect the negative (-) battery cable to the battery. Torque the bolt to 3.7 lb-ft. (5 N·m).
9. Reset the clock time and radio pushbuttons as desired.