DTC C2191/91 Vehicle Speed Signal Error (Test Mode DTC): Description

The tire pressure warning ECU receives a vehicle speed signal from the combination meter. This DTC is stored upon entering test mode, and cleared when a vehicle speed signal of 20 km/h (12 mph) is detected for 3 seconds or more. This DTC is output only in test mode.

HINT:

The meter CPU receives vehicle speed signals from this circuit. The vehicle speed sensor detects the voltage that varies according to the vehicle speed. The skid control ECU supplies power to the vehicle speed sensor. The skid control ECU detects vehicle speed signals based on the pulses of the voltage. The skid control ECU transmits vehicle speed signals as pulses to the meter CPU. A voltage of 12 V is output from the combination meter assembly and then input to the skid control ECU. The signal is changed to a pulse signal at the transistor in the combination meter assembly. A voltage of 12 V or 5 V is output from each ECU or relay and then input to the combination meter assembly. Each ECU controls the respective system based on the pulse signal.