Circuit Description
The electronic brake and traction control module (EBTCM) controls the PWM signal on the Desired Torque circuit while monitoring the wheel speed sensors to detect slippage. The PCM monitors the PWM signal and reduces engine torque as needed by retarding ignition timing, decreasing boost duty cycle (Vin 1), increasing air/fuel ratio, or, in severe cases, shutting OFF up to three 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. If the PCM detects a problem with the delivered torque circuit, DTC P1689 will set and traction control will be disabled. An ABS/TCS DTC may also be set. For further ABS/TCS DTC information, refer to ABS Description in 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 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
Check for the following conditions:
| • | Poor connection at the PCM -- Inspect harness connectors for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection |
| • | Damaged harness -- Inspect the wiring harness for damage. |
| • | If the harness appears to be OK, disconnect the PCM, turn ON the ignition and observe a Digital Multimeter connected between the Traction Control Delivered Torque control circuit and ground at the PCM harness connector while moving connectors and wiring harnesses related to the EBTCM. A change in voltage will indicate the location of the malfunction. |
If the DTC cannot be duplicated and is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set. Also refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Normally, ignition feed voltage should be present on the control circuit with the PCM disconnected and the ignition turned ON.
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Checks for a shorted component or a short to B+ on the control circuit. Either condition would result in a measured current of over 500 milliamps. Also checks for a component that is going open while being operated, resulting in a measured current of 0 milliamps.
-
Checks for a short to voltage on the control circuit.
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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 | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
Does the voltage measure near the specified value? | B+ | |||||||||
Does the current reading remain between the specified values? | 0.001-0.5 Amp (1-500 mA) | |||||||||
Does the voltage measure at the specified value? | 0 V | |||||||||
5 | Locate and repair short to voltage in the delivered torque control circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |||||||
6 |
Is the fuse blown? | -- | ||||||||
7 |
Did you find and correct the condition? | -- | -- | |||||||
8 |
Does the voltage measure near the specified value? | B+ | ||||||||
9 |
Did you find and correct the condition? | -- | ||||||||
10 |
Did you find and correct any conditions? | -- | ||||||||
11 |
Does the test lamp flash ON and OFF? | -- | Go to Diagnostic Aids | |||||||
12 |
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 find and correct the condition? | -- | -- | |||||||
14 | Replace the EBTCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake Systems. 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 DTC reset? | -- | System OK |
