P1808

DTC P1808: TC-SST-ECU temperature, fluid temperature sensor system (Correlation error)

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 checks that the temperature sensor and the fluid temperature sensor are normal.

DESCRIPTIONS OF MONITOR METHODS
The difference of the output between the ECU temperature sensor and fluid temperature sensor is large.

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC, stored in memory for the item monitored below)
^ Not applicable

Sensor (The sensor below is determined to be normal)
^ Not applicable

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.

JUDGMENT CRITERIA
^ Calculated temperature ("Temperature B: Fluid temperature sensor output" - "Temperature A: TC-SST-ECU temperature sensor output"): 20°C (36°F) or more. (12 seconds)

OBD-II DRIVE CYCLE PATTERN
The difference of the calculated temperature is 20°C (36°F) or less.

PROBABLE CAUSES
^ 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 scan tool MB991958, 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. Check whether the DTC is reset.
1. seconds after turning ON the ignition switch, check that the DTC is reset.
Q: Is DTC No. P1808 set?
YES: Replace the mechatronic assembly.
NO: Intermittent malfunction.