Diagnosis And Testing - Junction Block

The junction block does not incorporate any self diagnostic capability. Most of the electrical circuits incorporated into the vehicle must pass through the junction block at one point or another. The most efficient means of diagnosing a suspected junction block problem involves a simple continuity tester or ohm meter. Using the Wiring Diagrams as a guide trace the problem circuit to the proper junction block cavity and test all circuits in the effected circuit for proper continuity. A open or high resistance circuit is a sign of a problem. Some other possible junction block problems to look for are:

• Loose fuse receptacle terminals.
• Loose relay/circuit breaker receptacle terminals.
• Bent or distorted electrical circuit pins.
• Incorrect size fuse installed in junction block fuse cavity.
• Dark areas identifying a source of excess heat.
• Defective fuse, relay or circuit breaker installed in junction block cavity.