P0888 TCM Power Relay Sense Circuit

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. P0888 is the general fault of the sense line, without telling low, high or range apart. No maker documents it on its own; Subaru uses the low variant P0890.

Likely causes

Symptoms

• MIL on
• Limp mode in a fixed gear, no shifting
• Harsh engagement into D or R

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.