The electronic brake control module (EBCM) monitors the HydroMax assist relay and HydroMax motor for electrical continuity.

Ignition ON.

The conditions for setting the DTC are no longer present.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Brake Warning System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Press and release the brake pedal several times, each time the power brake booster pump relay should click.

1. Ignition OFF, disconnect the power brake booster pump relay.
2. Test for less than 1.0 ohm between the relay coil ground circuit terminal 86 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance

3. Test for less than 1.0 ohm between the relay switch ground circuit terminal 30 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition OFF, disconnect the brake booster pump harness connector at the EBCM.
5. Verify that a test lamp illuminates between the power brake booster relay switch B+ circuit terminal 87 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse 4 60A is open, test or replace the power brake booster pump motor.

6. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and B+.

⇒	If the test lamp illuminates, test the control circuit for a short to ground.

7. Connect the power brake booster pump relay harness connector at the EBCM.
8. Connect a 3A fused jumper wire between the relay ground circuit terminal 87 and the control circuit terminal 30. Verify the power brake booster pump motor is activated.

⇒	If it does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the power brake booster pump motor.

9. Connect a test lamp between the relay coil control circuit terminal 85 and the relay coil ground circuit terminal 86.
10. Press the brake pedal several times. The test lamp should turn ON and OFF when changing between the brake pedals pressed and depressed states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the EBCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the EBCM

11. Ignition OFF. Disconnect the EBCM harness at the power brake booster pump relay. Connect a test light between the EBCM brake booster pump motor signal terminal 10 and EBCM brake booster fluid flow switch signal terminal 28.
12. Press the brake pedal several times. The test lamp should turn ON and OFF when changing between the brake pedals pressed and depressed states.

⇒	If the test lamp is always OFF, test the brake switch signal circuit and the brake booster fluid flow switch signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the relay.

13. If all circuits test normal, test or replace the power brake booster pump relay.

Relay Test

1. Ignition OFF, disconnect the power brake booster pump relay.
2. Test for 1-5 ohms between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the 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 relay.

4. Install a 3A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.