Handbook 652 Body Electrical Diagnosis Shared Ground Points In the electrical system, a load ’ s ground point is often shared with other circuits. Before trying to locate a ground point in the vehicle to inspect it for trouble, test other circuits that share the same ground point. If another circuit which shares the ground point with your inoperative circuit works properly, then you know that the grounding point is OK. NOTE Verifying proper operation of other circuits with the same ground point does not eliminate the possibility of a problem on the ground side of the circuit before the ground point.
Also, a poor connection between ground point terminals “ stacked ” onto a single ground point could still be a problem cause. To find circuits sharing a ground point, refer to the Ground Point section of the EWD. Each ground point is listed with the names of all components and splices that are connected to it. You will notice there are numerous redundant grounds in Toyota vehicles. The redundant grounds are there to make sure that each circuit has a “ back-up ” ground in case a ground fails due to wire fatigue, corrosion or other cause. Some grounding failures can result in a current backfeed condition. When that happens, it is important to know what circuits share a ground connection.
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