P1871

DTC P1871: APS system (Signal abnormality)

CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

DIAGNOSTIC FUNCTION
TC-SST-ECU receives the periodic communication data from the engine control module via the CAN bus lines, and checks the data for abnormality.

DESCRIPTIONS OF MONITOR METHODS
The APS signal from the engine control module is determined to be abnormal.

MONITOR EXECUTION
^ Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC, stored in memory for the item monitored below)
^ P0841: Clutch 1 pressure sensor system (Poor performance)
^ P0842: Clutch 1 pressure sensor system (Output low range out)
^ P0843: Clutch 1 pressure sensor system (Output high range out)
^ P0846: Clutch 2 pressure sensor system (Poor performance)
^ P0847: Clutch 2 pressure sensor system (Output low range out)
^ P0848: Clutch 2 pressure sensor system (Output high range out)
^ P185D: Clutch open not possible
^ U0001: Bus off
^ U0100: Engine time-out error
^ P1803: Shift lever system (CAN or LIN time-out error)
^ P1870: Engine torque signal abnormality
^ P1872: Between shift lever and TC-SST system (Q-A function abnormality)

Sensor (The sensor below is determined to be normal)
^ Clutch 1 pressure sensor
^ Clutch 2 pressure sensor
^ APS
^ Shift lever-ECU

LOGIC FLOW CHARTS (Monitor Sequence)





DTC SET CONDITIONS

Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Time after TC-SST-ECU start: 5 seconds or more.

JUDGMENT CRITERIA
^ APS signal: SNA, or parity/toggle error.

OBD-II DRIVE CYCLE PATTERN
Receives the normal value of the APS signal, or the parity/toggle are normal.

PROBABLE CAUSES
^ The CAN bus line is defective.
^ APS malfunction
^ Malfunction of engine control module
^ Malfunction of TC-SST-ECU

DIAGNOSTIC PROCEDURE

Required Special Tools:
^ MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A

STEP 1. Scan tool CAN bus diagnostics
Using the scan tool, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.

STEP 2. Scan tool diagnostic trouble code.
Check if the diagnostic trouble code is set to the system other than TC-SST
Q: Is the DTC set?
YES: Perform the relevant troubleshooting.
NO: Go to Step 3.

STEP 3. Scan tool diagnostic trouble code.
After 15 seconds with the engine idle status, check that the diagnostic trouble code for engine is set. Diagnostic Trouble Code Descriptions
Q: Is the DTC set?
YES: Perform the relevant troubleshooting.
NO: Go to Step 4.

STEP 4. Check whether the DTC is reset.
After 15 seconds with the engine idle status, check that the DTC is reset.
Q: Is DTC No. P1871 set?
YES: Replace the mechatronic assembly.
NO: Intermittent malfunction.