0xD90B04 Trailer Control Modulator backup valve-Voltage Below Normal, Or Shorted To Low Source
Action: Check all cables and connectors from the TCM to the central ECU (including check for chafing damage). With valve wiring disconned from central ECU: resistance of valve should be in [6..17] Ohm, resistance between actual valve connection and all wires of different components on the same connector and to vehicle ground should be larger than 200 kOhm. If not ok then measure directly on TCM connector, valve should be in [6..17] Ohm. if not ok then replace TCM else repair wiring. If result is ok reconnect everything delete error code, check if error code appears again . If error is not detected again. The error is intermittent try to reproduce the error by moving cables and connectors. If error cannot be reproduced no further action is possible.
What you'll see
Symptom:
System reaction
SystemReaction: ESP control restricted. HSA off. Trailer brake off. Trailer Control - CFC is off. Yellow EBS Warning Lamp.
Diagnostic depth
Detection: Fault will be detected if valve is not activated and reading back hardware status information. If the output is less then 5 V for the duration of the detection time.
Cause: Damage in the wiring (low insulation restiance to vehicle ground or interruption) and/or connectors between TCM and central ECU, damaged TCM or central ECU