ECM Power Supply Relay, Checking

Observe all safety precautions: SAFETY PRECAUTIONS

View clean working conditions: CLEAN WORKING CONDITIONS

Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .

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

See Appropriate Wiring Diagram Information for component locations and connector views.

Special Tools And Workshop Equipment 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 Appropriate Wiring Diagrams for specific circuit information.
Ignition switched Off

Test Procedure

-- Remove the ECM Power Supply Relay -J317- from the fuse panel. Refer to Appropriate 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 appropriate System Wiring Diagram information.

-- 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 appropriate System Wiring Diagram information.

-- 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 Ω 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:

Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .