P1844

TCS TORQUE REDUCTION REQUEST CIRCUIT

Diagnostic Chart:

Wiring Diagram:

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 Transmission Control Module (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 Malfunction Indicator Lamp (MIL)/Service Transmission Lamp (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 35816-A. 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 Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact 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.

12. Check the circuit for the following conditions which may cause an intermittent problem:

^ 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 Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact 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.