ECM Power Supply Relay, Checking

ECM Power Supply Relay, Checking

Observe all safety precautions: => [ Safety Precautions ] Safety Precautions

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Prior to repair work, perform a preliminary check to verify the condition. Refer to => [ Preliminary Check ] Preliminary Check.

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools, testers and auxiliary items required

• Multimeter

• Wiring diagram

Test requirements

• The engine control module fuses OK

• Battery voltage at least 12.5 volts

• All electrical consumers switched off

• Vehicles with automatic transmission, shift selector lever in park or neutral

• A/C switched off

• Ground connections between engine/transmission/chassis OK

• Check for any open fuses. If found, locate the short on that circuit and replace the fuse before continuing. Refer to Wiring Diagrams for specific circuit information.

• Ignition switched Off

Test procedure

- Remove the ECM Power Supply Relay (J317) from the fuse panel. Refer to Wiring Diagrams for location.

Checking the supply voltage

- Turn the ignition switch ON

- Using a multimeter, measure the voltage of the ECM Power Supply Relay (J317) circuit, (socket 1/30).

Specified value: Battery voltage.

- Turn the ignition switch OFF

If the specified value was Not obtained:

- Check the power supply circuit to the ECM Power Supply Relay (J317) for an open circuit or a short circuit. Refer to Wiring Diagrams.

- Check the wiring connections for damage, corrosion, loose or broken terminals.

- Repair as necessary.

If the specified value was obtained:

- Turn the ignition switch ON

- Using a multimeter, measure the voltage of the ECM Power Supply Relay (J317) ignition circuit (socket 3/86).

- Turn the ignition switch OFF

Specified value: Battery voltage.

If the specified value was Not obtained:

- Check the power supply circuit to the ECM Power Supply Relay (J317) for an open circuit or a short circuit. Refer to Wiring Diagrams.

- Check the wiring connections for damage, corrosion, loose or broken terminals.

If the specified value was obtained:

Checking wiring

- Remove the Engine Control Module (ECM) (J623). Refer to the Repair Information for removal and installation procedures.

- Using a multimeter, measure the resistance of the circuit between the ECM Power Supply Relay (J317) terminal 85 and the Engine Control Module (ECM) (J623) T94/69. Refer to the applicable wiring diagram.

Specified value: 1.5 ohms Max.

If the specification was Not obtained:

- Check the wires for a short circuit to each other, a short to battery voltage, and a short to ground.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- Repair as necessary.

If no malfunction is found in the wiring and voltage supply was OK:

- Replace the ECM Power Supply Relay (J317).

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.