Cruze

Ignition Relay Diagnosis

The powertrain relay, is controlled by the engine control module (ECM) depending upon input from the ignition switch. Battery positive voltage is supplied to the relay coil and switch. When the ignition switch is turned to the ON position, the ECM will provide ground on the control circuit of the relay using a low side driver. This will allow voltage through the relay switch contacts to the components. The ECM monitors the voltage level on the control circuit of the relay.

The relay electrical contacts may be pitted or sticking. Replace the powertrain relay, if gently tapping or wiggling the powertrain relay causes a change in the relays operation.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL 43244 Relay Puller Pliers

For equivalent regional tools, refer to Special Tools .

Warning: An electric fan under the bonnet can start up even when the engine is not running and can injure you. Keep hands, clothing and tools away from any underbonnet electric fan.

1. Cycle the ignition from OFF to ON. You should hear and feel an audible click from the KR75 Powertrain Relay. Repeat as necessary in order to verify KR75 Powertrain Relay operation.
2. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

1. Ignition OFF, disconnect the KR75 Powertrain Relay.
2. Ignition ON, verify a test lamp illuminates between the KR75 Powertrain Relay coil ignition voltage circuit terminal 85 and ground.

⇒	If the test lamp does not illuminate, repair the KR75 Powertrain Relay coil ignition voltage circuit for a short to ground or an open/high resistance. Replace the fuse if necessary.

3. Ignition OFF, connect a test lamp between the KR75 Powertrain Relay coil control circuit terminal 86 and the KR75 Powertrain Relay coil ignition voltage circuit terminal 85.

⇒	If the test lamp is always ON, test the KR75 Powertrain Relay control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

4. Ignition ON. The test lamp should turn ON.

⇒	If the test lamp is always OFF, test the KR75 Powertrain Relay ECM control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

Note: The ignition voltage circuit is between the KR75 Powertrain Relay and the ECM. The ignition voltage is a feedback circuit.

5. Install a 20 A fused jumper wire between the KR75 Powertrain Relay switch B+ circuit terminal 30 and the KR75 Powertrain Relay switch ignition voltage circuit terminal 87.
6. Attempt to start the engine. The engine should start.

⇒	If the engine does not start, test the ignition voltage circuit between the KR75 Powertrain Relay and the K20 Engine Control Module for a short-circuit to ground or for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

7. If all circuits test normal, test or replace the KR75 Powertrain Relay.

Relay Test

1. Ignition OFF, remove the KR75 Powertrain Relay from the electrical center with the EL 43244 Relay Puller Pliers.
2. Test for 70-110 Ω between terminals 85 and 86.

⇒	If not within the specified range, replace the KR75 Powertrain Relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the KR75 Powertrain Relay.

4. Install a 20 A fused jumper wire between KR75 Powertrain Relay terminal 85 and 12 V. Install a jumper wire between KR75 Powertrain Relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than the specified range, replace the KR75 Powertrain Relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.