P0889 TCM Power Relay Sense Circuit Range/Performance

Some gearboxes draw their power through a relay, such as the transmission control relay in Chrysler's fuse box that feeds the solenoids. P0885 to P0887 cover the coil control of that relay, P0888 to P0892 its sense line, which reads back the switched output and compares it with the command. A dead relay leaves all solenoids without power, so the gearbox drops into its hydraulic emergency gear. P0889 means the read-back voltage does not fit the switching state or the system voltage: clearly below battery voltage, a voltage drop across the contact or a delayed drop-out. No maker publishes a strategy.

Likely causes

Symptoms

• MIL or gearbox warning
• Occasional limp mode

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov.