NOTE: Check connector while it is connected unless otherwise specified. Be sure to check again from the beginning and proceed in order to prevent secondary trouble caused by repair work. When making checks with vacuum hose disconnected from the vacuum switch and the engine on, be sure to plug the hose.

Start and warm engine until coolant temperature reaches 176° F (80° C). Turn engine and ignition switch off. Connect "Test Mode" connector. Turn ignition switch to "ON" position but DO NOT start engine.
Ensure that ECS lamp turns on. If not, proceed to TEST MODE DIAGNOSTIC CHART "B". If lamp turns on, read indicated trouble code. If there is no trouble code indicated, replace ECM. If there is an indicated trouble code, ensure that it applies to the vehicle model.
If trouble code does apply, proceed to TEST MODE DIAGNOSTIC CHART "A". If trouble code does not apply, check to see if selection code indicated is in the SELECTION CODE chart.
If it is, ensure that its corresponding voltage applies to the vehicle. If it does, replace ECM. If not, make repairs as indicated by SELECTION CODE chart and SELECTION CODE CHART REPAIR PROCEDURES.

Fig 1: Selection Code Chart

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

Test Mode

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?