Snowplow Roof Beacon (Lamp) Inoperative (Install Bypass Harness)

Some customers may comment that the roof mounted snowplow beacon (lamp) is inoperative.

Vehicles may have been built without the required battery positive voltage circuit #2340 in the IP harness.

Install a bypass harness adding circuit #2340 to the IP harness using the service procedure listed below.

1. Construct a bypass harness.

•	Obtain standard stock 12 gauge red wire and cut to a length of 1000 mm (40 in).

•	Strip 5 mm (3/16  in) of insulation from each end of the wire.

•	Crimp the terminals, P/N 12110842, to each end of the wire.

•	Solder the crimps with rosin core solder.

2. Obtain a 7 mm (1/4 in) inside diameter vacuum tube or other equivalent hollow plastic tube approximately 152 to 203 mm (6 to 8 in) long. Apply an angle cut to one end of the tube.
3. Apply WD-40 lubricant to the outer area of the tube, especially near the angle cut end.
4. From underhood, locate and untape the smaller pass-through grommet at the right side of the brake booster.
5. Inserting the "angle cut" lubed portion of the tube (outside to inside), slowly manipulate the plastic tube inside the nozzle of the grommet, proceeding cautiously so as to not damage any existing wires.
6. Once the tube is through the grommet, insert one end of the bypass wire and push through the tube until the wire is through the grommet and past the inserted end of the tube.
7. Once the wire is through the grommet, the tube can be removed. Pull enough wire through the grommet to get to the IP relay block.
8. Re-tape harness at the grommet.
9. Route the wire underhood along the IP harness branch to the underhood electrical center.
10. Remove the left fender upper brace.
11. Remove the underhood electrical center cover.
12. Push on the tab so that the electrical center can be rotated exposing the underside.
13. Remove the IP 68-way (light gray) connector (C1) from the electrical center.
14. Remove the TPA from the connector and install the terminal of the new wire into cavity E11.
15. Reinstall the TPA, the connector, the electrical center and the cover.
16. Carefully secure the wire to the IP harness with tape, ensuring proper routing and clearance from sharp objects or pinch points.
17. Inside the vehicle, route the new wire to the IP relay block, securing as needed to the main IP harness.
18. Remove the IP relay block from it's mounting bracket and remove the 68-way (light gray) connector (C1) from the I/P.
19. Remove the TPA from the connector and install the terminal of the new wire into cavity D12.
20. Reinstall the TPA and connector onto the relay block; reinstall the relay block into the bracket.

The terminal is included in Packard Terminal Repair Kit J 38125-A or available from GMSPO.

For vehicles repaired under warranty, use: