GM 15291746
Junction Block

The replacement process of an underhood Fuse Box or junction block begins by removing the battery and unfastening positive battery cable leads from the Fuse Box. Once the leads are relocated away from the Fuse Box proceed. The first step involves taking off the Fuse Box cover as well as every Fuse within. A flat-blade tool should be used to separate the 4 tabs connecting the Fuse Box to the battery tray while also removing the connector cover from the Fuse Box. A flat-bladed tool can remove locking pins from the body harness connector while disconnecting it and other wiring harness connectors from the junction block after loosening the 4 Fuse Box top bolts. To install the Fuse Box first reverse it and then connect harness electrical connectors followed by locking the power supply connector. Semisynthetic torque tools should be used to tighten bolts securing engine and forward lamp wiring harness connectors and instrument panel (I/P) connectors to 7 n.m (62 lb in). The Fuse Box cover must be installed first followed by placing the Fuse Box with its right side facing up until it snaps into position at the battery tray retainer tab. For the last step reinstall all fuses together then use the positive battery cable lead to attach it to the underhood Fuse Box stud while tightening the retaining nut to 10 n.m (89 lb in). Place the battery together with the Fuse Box cover for final installation.

The first step to replace the rear electrical center or junction block requires disconnecting the battery negative cable. The procedure for gmc envoy xl requires left second row seat removal but chevrolet trailblazer and gmc envoy users need to set their left second row seat to cargo position. The process begins with opening the rear electrical cover after which technicians remove the battery terminal nut from the junction block allowing them to extract the Body Control Module (BCM) from the same area. Before proceeding remove the junction block from the block base by first unlatching its tabs then loosening its retaining bolts from the electrical connectors. Remove the Instrument Panel Harness Connector, mobile telephone harness connector, Body Wiring Harness Connector and console harness connector and headliner harness connector from the junction block. Remove all retaining nuts that fasten the floor studs to the block base then remove the base from the floor panel. To install the procedure requires setting the block base onto floor studs before tightening retaining nuts to 10 n.m (88 lb in). Safely connect the mobile telephone harness connector to the junction block base together with Instrument Panel Harness Connector and console harness connector and Body Wiring Harness Connector and headliner harness connector . Secure the junction block onto the block base then bead it down with three bolts which require tightening to 3.5 n.m (31 lb in). Thebcm installation at the rear electrical center includes connecting the junction block battery feed terminal nut while tightening it to 10 n.m and restoring the center cover. When working on chevrolet trailblazer or gmc envoy vehicles position the left second row seat into a passenger state while gmc envoy xl owners should replant their left second row seat. Reconnect the battery negative cable as the final step.

Turn the electrical center upside down and install the electrical center harness connectors, followed by the locking pin to the power supply connector.

Remove the electrical center cover, followed by all fuses and relays.

Remove the junction block bracket retaining bolts to take the bracket out of the vehicle.