Basic Circuit Checks: Description: Notes

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.

Basic circuit checks help to minimize pinpoint test steps by providing a procedure to diagnose harness faults associated with the electronic engine control (EEC) system. The following techniques provide helpful reminders for diagnosing open circuits (continuity), shorts to ground, and shorts to power.

The suspect circuit must be isolated before testing.
When disconnecting any harness connector, always inspect for damaged or pushed out pins, corrosion, and loose wires. Repair as necessary.
The digital multimeter (DMM) must be set to the correct scale.
The techniques do not apply in all situations, therefore, it is necessary to follow each pinpoint test step accurately and completely.
General resistance and voltage values are specified below. Always use the pinpoint test values if they differ.
Always turn the key to the OFF position unless directed otherwise by the pinpoint test.

Each of the following procedures require the powertrain control module (PCM) and component to be disconnected to isolate the harness.