Circuit Description
If the ABS/Traction Control System detects the excessive wheel spin, the ABS controller sends a signal to the ECM requesting reduced engine torque. The ECM reduces engine torque by retarding spark timing in response to this signal. This signal also travels to the TCM. The TCM monitors this signal in order to prevent redundant requests for torque reduction which could result in excessive spark retard. The Traction Control Torque Reduction Request Circuit is pulled up to B+ within the ABS controller. The ABS controller induces a signal on the circuit by Pulse Width Modulating the circuit to ground. The signal frequency is constant at approximately 100 Hz. The requested amount of timing retard passes over to the TCM by varying the duty cycle of this signal.
Conditions For Running The DTC
Tests continuously
Conditions for Setting the DTC
| • | The TCM detects an open, short to ground or power on the Traction Control Torque Reduction Request Circuit. |
| • | Conditions meet for 65 ms |
Action Taken When the DTC Sets
| • | The MIL/STL will not illuminate. |
| • | The TCM memory stores the DTC at the time of the first failure. |
| • | Traction Control disables. |
Conditions for Clearing the MIL/DTC
| • | A History DTC clears after forty consecutive warm-up cycles, if no failures report by this diagnostic or any other non-emission related diagnostic. |
| • | TCM battery voltage interrupts. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
For any test that requires probing the TCM harness connector or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit will prevent damage to the harness connector terminals.
Check for the following conditions:
| • | Poor connections at the TCM 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 Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help in order to locate the fault. |
Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
| • | Poor connections at the ECM or TCM. Inspect 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 Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. |
| • | Misrouted harness. Inspect the harness in order to ensure that the harness does not route too close to any high voltage wires such as spark plug leads, or too close to high current devices such as the alternator, electric motors, solenoids etc. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help to locate the fault. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the DVM indicate the specified voltage? | B+ | ||
3 |
Does the DVM indicate the specified voltage? | B+ | ||
4 |
Is the continuity indicated? | -- | ||
5 | Use the DVM J 39200 in order to check the continuity between the Traction Control Torque Reduction Request Circuit and ground. Is the continuity indicated? | -- | ||
6 | Use the test light J 34142-B connected to ground in order to probe the Traction Control Torque Reduction Request Circuit at the TCM harness connector. Does the test light illuminate? | -- | ||
7 | Repair the open or high resistance request circuit. Is the action complete? | -- | -- | |
8 | Repair the request circuit shorted to ground. Is the action complete? | -- | -- | |
9 | Repair the request circuit shorted to B+. Is the action complete? | -- | -- | |
10 | Check the ABS harness connector for a poor connection or poor terminal tension. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for the proper procedure. Was a problem found and corrected? | -- | Go to Antilock Brake System (ABS) | |
11 |
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 currently on the vehicle. Replace the ECM. Refer to Engine Controls, On Vehicle Service, ECM. Is the action complete? | -- | -- | |
Check the TCM harness connector for a poor connection or poor terminal tension. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. Was a problem found and corrected? | -- | Go to Test Description | ||
13 |
Is DTC P1844 set? | -- | ||
14 | Were there any additional DTCs noted during the Powertrain or Transmission OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | |
15 | Does the Transmission now function properly? | -- | System OK | Go to Functional Test |
