DO NOT perform any CIRCUIT TEST unless specified by QUICK TEST . Ensure all non-EEC-IV related faults are corrected. DO NOT replace any part unless directed to do so. When more than one service code is received, start with first code displayed.
DO NOT measure voltage or resistance at ECA or connect any test lamp to ECA unless specified. All measurements are made by probing REAR of the connector. Isolate both ends of a circuit and turn key off whenever checking for shorts or continuity, unless specified.
Disconnect solenoids and switches from harness before measuring continuity, resistance, or applying 12 volts. Follow each test step in order until fault is found. After each repair, check all component connections and repeat CIRCUIT TEST .
An "open" is defined as any resistance reading higher than 5 ohms, unless otherwise specified. A "short" is defined as any resistance reading less than 10,000 ohms to ground, unless otherwise specified.
On CIRCUIT TEST Q , to prevent replacement of good components, be aware that non-EEC-IV related areas may also be at fault.

NOTE: Fuel contaminated engine oil will affect some service codes. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST . If problem is corrected, change engine oil and filter.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

How To Use Circuit Tests

Use the Manual With the Right Hardware

When to See a Mechanic