P0891

Symptom:
P0891-TRANSMISSION RLY ALWAYS ON

When Monitored:
When the ignition is turned from the "off" position to the "run" position and/or the ignition is turned from the "crank" position to the "run" position.

Set Condition:
This DTC set if the Transmission Control Module (TCM) senses greater than 3 volts at the Transmission Control Relay Output circuits at the TCM prior to the TCM energizing the relay.

Note: Due to the integration of the Powertrain and Transmission Control Modules, the transmission part of the PCM has its own specific power and ground circuits.

Test 1:

Test 2-5:

Test 6-7:

POSSIBLE CAUSES
- TRANSMISSION CONTROL RELAY STUCK CLOSED
- TRANSMISSION CONTROL RELAY CONTROL CIRCUIT SHORT TO VOLTAGE
- TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT SHORT TO VOLTAGE
- POWERTRAIN CONTROL MODULE
- INTERMITTENT WIRING AND CONNECTORS