For 1990-2009 cars
ABS Components
Antilock Brake System Schematics

### Circuit Description

The RPM signal circuit provides the EBTCM with an indication of engine RPM to help determine TCS control methods and rates when a TCS event takes place.

### Conditions for Setting the DTC

• | There is a short to ground.

• | There is a short to voltage.

• | There is an open in the circuit.

• | There is a malfunctioning ECM.

• | There is a malfunctioning EBTCM

### Action Taken When the DTC Sets

• | A malfunction DTC is stored.

• | The TC indicator lamp is turned on.

• | The TCS is disabled. ABS remains functional.

### 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

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. If the instrument panel tachometer is working properly, the cause of the malfunction is most likely between splice S228 and the EBTCM, or the EBTCM itself.

2. The TCM must be disconnected in this step to properly check for a short to ground.

#### DTC 31 - RPM Signal Circuit Malfunction

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to A Diagnostic System Check
2 |

1. Start the engine.
2. Vary the engine RPM with the throttle while observing the I/P tachometer.

Does the I/P tachometer work properly as the engine RPM changes?

--

Go to Step 3

Go to Step 4

3 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the ECM connector from the ECM.
3. Disconnect the 25-pin EBTCM connector from the EBTCM.
4. Install the J 39700 Universal Breakout Box with the J 39700-250 Cable Adapter to the EBTCM harness only.
5. Use a J 39200 DMM to measure the resistance between the ECM harness connector terminal 80 and the J 39700 terminal 3.

Is the resistance within the specified range?

0-2 ohms

Go to Step 9

Go to Step 11

4 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the ECM connector from the ECM.
3. Disconnect the 25-pin EBTCM connector from the EBTCM.
4. Install the J 39700 Universal Breakout Box with the J 39700-250 Cable Adapter to the EBTCM harness only.
5. Use a J 39200 DMM to measure the resistance between the ECM harness connector terminal 80 and the J 39700 terminal 3.

Is the resistance within the specified range?

0-2 ohms

Go to Step 5

Go to Step 12

5 |

1. Disconnect the TCM connector from the TCM.
2. Use a J 39200 DMM to measure the resistance between the J 39700 terminal 3 and ground.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 6

Go to Step 13

6 |

1. Turn the ignition switch to the RUN position
2. Use a J 39200 DMM to measure the voltage between the J 39700 terminal 3 and ground.

Is the voltage within the specified range?

0-2 V

Go to Step 7

Go to Step 14

7 |

1. Inspect the ECM connector for the following:

• | Inspect for damage.

• | Inspect for poor terminal contact.

• | Inspect for corrosion.

2. Inspect the 25-pin EBTCM connector for the following:

• | Inspect for damage.

• | Inspect for poor terminal contact.

• | Inspect for corrosion.

3. Ensure both the ECM connector and the 25-pin EBTCM connector are properly retained when connected.

Are the following signs present on either connector:

• | Is poor terminal contact present?

• | Is corrosion present?

• | Is damaged terminals present?

--

Go to Step 15

Go to Step 8

8 |

1. Reconnect all the connectors.
2. Disconnect the scan tool if previously connected.
3. Start the engine.

Did DTC 31 reset?

--

Go to Step 10

Go to A Diagnostic System Check

9 | Replace the EBTCM. Refer to EBTCM Replacement . Is the repair complete? | -- | Go to A Diagnostic System Check | --
10 | Suspect ECM. Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls. Is the repair complete? | -- | Go to A Diagnostic System Check | --
11 | Repair an open between splice S228 and the 25-pin EBTCM harness connector terminal 3. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
12 | Repair an open between splice S228 and the ECM harness connector terminal 80. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
13 | Repair a short to ground in the engine RPM input circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
14 | Repair a short to voltage in the engine RPM input circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
15 | Replace all the terminals or replace the connectors that exhibit signs of the following:

• | That exhibit signs of poor terminal contact.

• | That exhibit signs of corrosion.

• | That exhibit 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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