For 1990-2009 cars
Engine Controls Components
Cell 20: EBTCM and Theft Deterrent Module
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

A processed wheel speed sensor signal is sent from the ABS controller to the Theft Deterrent Module. The signal is then sent from the Theft Deterrent Module to the ECM. The ECM calculates vehicle speed from this signal. The Vehicle Speed/Theft Deterrent Signal circuit is pulled up to B+ within the ECM. This DTC covers this circuit from the Theft Deterrent Module to the ECM. The circuit from the ABS controller to the Theft Deterrent Module is covered by the ABS controller diagnostics.

### Conditions For Running The DTC

• | The engine speed is greater than 1960 RPM.

• | The engine load is greater than 3.2 ms but less than 4.2 ms.

### Conditions For Setting The DTC

The vehicle speed signal is less than 3 mph for longer than 5 seconds.

### Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

### Conditions for Clearing the MIL/DTC

• | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.

• | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The ECM battery voltage is interrupted.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

• | Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Control Module Diagnosis for the proper procedure.

• | Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc.

• | Damaged harness. Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault.

| If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged.

Refer to Symptoms for the Intermittents.

### Test Description

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

1. This step verifies that the fault is currently present.

2. The test light connected to B+ is used to simulate the B+ pull-up within the ECM. The DVM can be connected to the shaft of the test light and battery ground. The momentary frequency signal verifies the initial communication between the theft deterrant system and the ECM.

#### DTC P0501 - Vehicle Speed Signal

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Notice for Vehicles With Independent Suspension: Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

1. Turn off the ignition.
2. Raise the drive wheels.
3. Start the engine.
4. Turn off the traction control system (if so equipped).
5. The engine is idling in gear.

Does the scan tool indicate a vehicle speed above the specified value?

0.0 mph/km/h

Refer to Diagnostic Aids

Go to Step 3

3 |

1. Turn off the ignition.
2. Disconnect the ECM.
3. Connect the test light J 34142-B from B+ to the Vehicle Speed/Theft Deterrent Signal circuit in the ECM connector and leave the test light in place.
4. Using DVM J 39200 set to AC, Hz, 4 volt scale, measure the voltage between the Vehicle Speed/Theft Deterrent Signal circuit in the ECM harness connector and ground.
5. While monitoring the DVM J 39200 , turn on the ignition, leaving the engine off.

Does the DVM momentarily indicate frequency within the specified range?

100 to 900 Hz

Go to Step 5

Go to Step 4

4 |

1. Turn off the ignition.
2. Disconnect the Theft Deterrent Module harness connector.
3. Check the Vehicle Speed/Theft Deterrent Signal Circuit for the following conditions:

• | Open Circuit

• | Short to ground

• | Short to power

Was a problem found?

100 to 900 Hz

Go to Step 6

Go to Step 7

5 |

1. Turn OFF the ignition.
2. Disable the SIR system.
3. Remove the steering wheel lower cover. Refer to Repair Instructions, Steering Wheel and Column - Tilt
4. Start the engine.
5. Disconnect the theft deterrent harness connector.
6. Connect the signal generator tester J38522 to the vehicle signal speed circuit in the theft deterrant module harness connector. Connect one connector to the signal circuit and the other connector to ground.
7. Turn on the tester and set the tester to 12V, 50% duty cycle 600 Hz.

Does scan tool indicate a speed above the specified value?

0.0 mph/km/h

Go to Antilock Brake System (ABS)

Go to Step 8

6 | Repair the Vehicle Speed/Theft Deterrent Signal circuit between the Theft Deterrent Module harness connector and the ECM. Is the action complete? | -- | Go to Step 10 | --
7 | Check for poor connections/terminal tension at the Theft Deterrent Module harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .

Was a problem found and corrected?

--

Go to Step 10

Go to Section 9, Theft Deterrent System

8 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .

Was a problem found and corrected?

--

Go to Step 10

Go to Step 9

9 | Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 10

--

10 |

1. Clear the DTCs with the scan tool.
2. Turn off the ignition for 15 seconds.
3. Operate the vehicle with the conditions that are required for this vehicle to run. Refer to Conditions for Running the DTC.
4. Check for any DTCs.

Is this DTC set?

--

Go to Step 2

Go to Step 11

11 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | The System is OK