P0891 - TCM Power Relay Sense Circuit High
P0891 Possible Causes
- Faulty Transmission Control Module (TCM) Power Relay
- Transmission Control Module (TCM) Power Relay harness is open or shorted
- Transmission Control Module (TCM) Power Relay circuit poor electrical connection
How is the P0891 code repair?Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
What is the cost to diagnose the P0891 code
Labor: 1.0The cost to diagnose the P0891 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
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- Engine Light ON (or Service Engine Soon Warning Light)
P0891 MeaningThe transmission control relay is used to supply power to the solenoid pack when the transmission is in normal operating mode. When the relay is off, no power is supplied to the solenoid pack and the transmission is in Limp-in mode. The relay output is fed back to the Powertrain Control Module (PCM). It is referred to as the Transmission Control Relay Output circuit or switched battery.
Immediately after a controller reset (ignition key turned to the run position or after cranking engine), the PCM verifies that the relay contacts are open by checking for no voltage at the switched battery terminals. After this is verified, the voltage at the pressure switches is checked. There should be no voltage on the pressure switches at this time. The PCM will then activate the relay.
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