The transmission control relay directs power from the vehicle’s electrical system to the transmission solenoids. If there is a performance problem between the transmission TCR and the ECU, a P0889 DTC will be saved by the ECU.
How Serious is the Code?
The P0899 diagnostic trouble code is quite serious, because it means the solenoids inside of your transmission are not receiving power. When this happens, transmission will go into what is called Limp Mode, where it will be restricted to a single forward gear.
Symptoms of a P0889 include:
- Limp mode
- Transmission will not change gears
- Wiring or connectors damage
- Failed transmission control relay
- ECU or TCM programming problems
How to Diagnose the Code?
In order to diagnose a P0889 OBDII trouble code, the mechanic will have to determine if the problem lies with the transmission control relay, a blown fuse or damaged wiring/connectors. The problem could also be caused by the TCM not sending and ‘On’ command/power to the transmission control relay, which can be caused by programming errors or a faulty transmission control unit.
What Repairs Will Fix P0889?
- Repair or replace damaged wiring and/or connectors
- Replace transmission control relay
- Update ECU or TCM software