Circuit Description
The electronic brake and traction control module (EBTCM) controls the pulse width modulated (PWM) signal on the desired torque circuit while monitoring the wheel speed sensors to detect slippage. The powertrain control module (PCM) monitors the PWM signal and reduces the engine torque as needed by retarding the ignition timing, decreasing the boost duty cycle, and increasing the air/fuel ratio, or, in severe cases, shutting OFF up to 3 fuel injectors. The PCM sends a PWM signal to the EBTCM on the delivered torque circuit informing the EBTCM of response made to the desired torque signal. A problem with the delivered torque circuit should cause DTC P1689 to set and the traction control system (TCS) to be disabled. An ABS/TCS DTC may also be set. For further ABS/TCS DTC information, refer to Antilock Brake Systems.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | An improper voltage level has been detected on the output circuit for the traction control delivered torque output circuit. |
| • | The above conditions are present for at least 30 seconds. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
Numbers below refer to the step numbers on the Diagnostic Table:
-
Normally, ignition feed voltage should be present on the control circuit with the PCM disconnected and the ignition turned ON.
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Tests for a shorted component or a short to battery positive voltage on the control circuit. Either condition would result in a measured current of over 500 milliamps. Also tests for a component that is going open while being operated, resulting in a measured current of 0 milliamps.
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Tests for a short to voltage on the control circuit.
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
Is voltage near the specified value? | B+ | |||||||||
Does the current reading remain between the specified values? | 0.001-0.5 Amp (1-500 mA) | |||||||||
Is voltage at the specified value? | 0.0V | |||||||||
5 | Locate and repair short to voltage in the delivered torque control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
6 |
Is the fuse open? | -- | ||||||||
7 |
Did you complete the repair? | -- | -- | |||||||
8 |
Is voltage near the specified value? | B+ | ||||||||
9 | Test the delivered torque control circuit for an open or a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
10 |
Did you find and correct the condition? | -- | ||||||||
11 |
Does the test light flash ON and OFF? | -- | Go to Diagnostic Aids | |||||||
12 | Test the delivered torque control circuit for a poor connection at the PCM. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
13 | Locate and repair open in ignition feed circuit to the EBTCM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
14 | Replace the EBTCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the replacement? | -- | -- | |||||||
|
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||
16 |
Does the scan tool indicate DTC P1689 failed this ignition? | -- | System OK |
