For 1990-2009 cars
ABS Components
Antilock Brake System Schematics

### Circuit Description

The pump motor relay closes and provides voltage to operate the pump when it is grounded by the EBTCM. Once the motor circuit is energized a pump on signal is sensed by the EBTCM to verify pump operation.

### Conditions for Setting the DTC

• | Voltage is present at the pump motor for 5 seconds without pump motor relay activation from the EBTCM.

• | Voltage is NOT present at the pump motor within 60 milliseconds after the EBTCM requests pump motor relay activation.

• | The pump motor runs for longer than 100 milliseconds after the EBTCM requests pump motor cancellation.

• | The motor GND circuit is open.

• | There is a pump motor malfunction.

### Action Taken When the DTC Sets

• | A malfunction DTC is stored.

• | The ABS and the TC indicator lamps are turned on.

• | The ABS and the TCS are disabled.

### Conditions for Clearing the DTC

• | The condition for DTC is no longer present.

• | The scan tool Clear DTCs function is used.

• | 100 drive cycles have passed with no DTCs detected.

### Diagnostic Aids

The Return Pump Relay Test, located in Special Functions of the scan tool can be used to determine if the pump circuit is operating properly. This test can only be performed if DTC 35 is not currently set.

Perform a thorough inspection of the wiring. Perform a thorough inspection of the connectors. Failure to carefully and fully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. This step checks for a short to ground on the EBTCM side of the fuse. Check both fuse block terminals to verify. The fuse terminals are not identified.

2. This step checks if the fuse opens when the ignition switch is turned to the RUN position, and the ABS/TCS performs the self test during the test drive.

3. This step determines if a short to ground in the pump is causing the open fuse. If the pump checks OK, the short is in the EBTCM.

4. If the pump is running constantly in this step, the pump relay contacts are stuck closed.

#### DTC 35 - Return Pump Relay Circuit Malfunction

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: Perform the following checks before testing:

• | Check that the battery is fully charged.

• | Check that the charging system is operating properly.

1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to A Diagnostic System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Remove the 80 amp power distribution MaxiFuse® V4.
3. Inspect the 80 amp power distribution MaxiFuse® V4.

Is the fuse open?

--

Go to Step 4

Go to Step 3

3 | Use a J 39200 DMM to measure the resistance between the pump motor ground stud and ground. Is the resistance within the specified range? | 0-5 ohms | Go to Step 5 | Go to Step 17
4 | Use a J 39200 DMM to measure the resistance between both of the pump distribution fuse block terminals of the MaxiFuse® V4 and ground. Is the resistance within the specified range on either terminal? | OL (Infinite) | Go to Step 7 | Go to Step 6
5 |

1. Reinstall the MaxiFuse®.
2. Disconnect the 4-pin EBTCM connector C2 from the EBTCM.
3. Use a J 39200 DMM to measure the voltage between the 4-pin EBTCM harness connector C2 terminal 2 and ground.

Is the voltage within the specified range?

Battery Voltage

Go to Step 9

Go to Step 15

6 |

1. Disconnect the 4-pin EBTCM connector C2 from the EBTCM.
2. Use a J 39200 DMM to measure the resistance between the 4-pin EBTCM harness connector C2 terminal 2 and ground.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 13

Go to Step 16

7 |

1. Install a new MaxiFuse®.
2. Test drive the vehicle above 6 km/h (3.5 mph).
3. Turn the ignition switch to the OFF position.
4. Recheck the MaxiFuse®.

Is the MaxiFuse® open?

--

Go to Step 8

Go to A Diagnostic System Check

8 |

1. Disconnect the 25-pin and disconnect the 4-pin EBTCM connectors from the EBTCM.
2. Remove the EBTCM. Refer to EBTCM Replacement .
3. Remove the EBTCM bracket. Refer to Brake Pressure Modulator Valve (BPMV) Replacement .
4. Disconnect the pump motor ground.
5. Use a J 39200 DMM to measure the resistance between the pump motor power connector terminal and the pump motor case.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 13

Go to Step 14

9 |

1. Inspect the 4-pin EBTCM connector, paying special attention to terminals 2 and 3, for the following signs:

• | Inspect for damage.

• | Inspect for poor terminal contact.

• | Inspect for corrosion.

2. Check that the 4-pin EBTCM connector is properly retained when connected.

Are the following signs evident:

• | Is poor terminal contact evident?

• | Is corrosion evident.

• | Is damaged terminals evident?

--

Go to Step 18

Go to Step 10

10 |

1. Disconnect the 25-pin EBTCM connector from the EBTCM.
2. Remove the EBTCM. Refer to EBTCM Replacement .
3. Remove the EBTCM bracket. Refer to Brake Pressure Modulator Valve (BPMV) Replacement .
4. Use a J 39200 DMM to measure the resistance between the pump motor power connector terminal and the pump motor ground stud.

Is the resistance within the specified range?

0.05-10 ohms

Go to Step 11

Go to Step 14

11 |

1. Reinstall the EBTCM bracket. Refer to Brake Pressure Modulator Valve (BPMV) Replacement .
2. Reinstall the EBTCM. Refer to EBTCM Replacement .
3. Reconnect all the connectors.
4. Disconnect the scan tool.
5. Turn the ignition switch to the RUN position with the engine off.

Is the pump running constantly?

--

Go to Step 13

Go to Step 12

12 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the scan tool if the scan tool is connected.
3. Test drive the vehicle above 6 km/h (3.5 mph).

Did DTC 35 reset?

--

Go to Step 13

Go to A Diagnostic System Check

13 | Replace the EBTCM. Refer to EBTCM Replacement . Is the repair complete? | -- | Go to A Diagnostic System Check | --
14 | Replace the BPMV. Refer to Brake Pressure Modulator Valve (BPMV) Replacement . Is the repair complete? | -- | Go to A Diagnostic System Check | --
15 | Repair an open in CKT A290. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
16 | Repair a short to ground in CKT A290. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
17 | Repair an open or a loose connection in CKT F372. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
18 | Replace all the terminals or replace the connector that exhibits the following signs:

• | That exhibits signs of poor terminal contact.

• | That exhibits signs of corrosion.

• | That exhibits signs of damaged terminals.

Refer to Connector Repairs or Repairing Connector Terminals in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

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