Action: Check the cables and connectors between central ECU and TCM (including check for chafing damage). Activate AM mode. Remove connector which supports the TCM at ECU side. Read out sensor supply voltage by diagnosis. If voltage is higher than 0.5 V replace ECU. Measure the voltages between the ECU pins. Reference is sensor GND. Voltage of TCM supply should be in range [UB - 3 V..UB + 3 V]. Voltage of sensor supply should be below 0.5 V. If test fails an ECU problem is existing. Connect TCM connector to ECU. Disconnect TCM on TCM side. Read out sensor supply voltage by diagnosis. If voltage is higher than 5.8 V problem is on wiring harness or connector. Measure TCM pressure sensor supply voltage from wiring harness to vehicle ground. Voltage should be below 1 V. If voltage is higher than 1 V repair wiring harness. Measure TCM pressure sensor supply voltage from wiring harness to TCM_PS_GND. Voltage should be below 0.5 V. If voltage is higher than 0.5 V repair wiring harness. Measure resistance on wiring harness between TCM_PS_GND and vehicle GND. Resistance should be lower than 5 Ohm. If resistance is higher than 5 Ohm repair wiring harness. Disconnect connector on ECU side. Fault trace by resistance between pressure sensor supply connection and all wires of different components on the same connector (TCM not connected). Resistance from sensor supply to all wires should be higher than 200 kOhm. If no fault is found, then connect cable on ECU side (Aftermarket diagnostic mode still active, TCM disconnected). Check the voltages on the TCM connector. Voltage of TCM supply should be in range [UB - 3 V..UB + 3 V]. Voltage of sensor supply should be below 0.5V. If test fails an wiring harness or connector problem is existing. If the voltages are in the defined range move wiring harness to reproduce the fault. If the fault can be reproduced (voltages outside the defined range) the error is located in the wiring harness or the connector. Connect TCM. Read out sensor supply voltage by diagnosis. If voltage is higher than 5.8 V problem is on TCM. If no error found then deactivate after market mode and apply Reset to ECU. If there is no active fault code move the harness to reproduce the fault. If the failure can be reproduced (fault code set) the error is located in the wiring harness or connector. If no error can be found check if the pressure on the coupling head measured with an external pressure sensor equals the pressure measured with the TCM pressure sensor in the whole range (0..8 bar) with a deviation < 0.4 bar.

Diagnostic depth