P1895

Circuit Description
The torque reduction signal from the Transmission Control Module (TCM) informs the Engine Control Module (ECM) that a gearshift is in progress. The ECM responds by reducing the engine torque to enable a smooth gearshift transition. If either the torque reduction signal is out of range or the ECM does not receive a shift-in-progress message via the serial data link within 250 milliseconds of the correct torque reduction signal, Diagnostic Trouble Code (DTC) P1895 is set.

Conditions for Setting the DTC
- Torque reduction signal low is not between 1.1 and 7.5 milliseconds.
- Shift-in-progress message is not received within 250 milliseconds of the correct torque reduction signal.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will not illuminate.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside the insulation.

Check for a poor connection or damaged TCM/ECM harness. Inspect the torque reduction signal circuit for the following conditions:
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminal-to-wire connection
- Damaged harness

Steps 1 - 8:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
3. If the ECM output voltage is as specified, check the ECM and TCM harness connectors for poor terminal-to-wire connection, damaged terminals or improper mating.
6. The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for the ECM reprogramming.