Coolant temperature gauge signal (Engine management system - V8)

Function The illumination of the low fuel level warning lamp in the instrument cluster triggers the low fuel level signal to be sent to the ECM. This signal is processed via pin 8 of connector C0637 of the ECM.

Should a misfire occur while the fuel level is low, the following fault code may be evident and can be retrieved by TestBook.

Coolant temperature gauge signal

The ECM controls the temperature gauge in the instrument cluster. The ECM sends a coolant temperature signal to the temperature gauge in the instrument cluster in the form of a PWM square wave signal.

The frequency of the signal determines the level of the temperature gauge.

Conditions The ECM operates the PWM signal under the following parameters: l -40 °C (-40 °F) = a pulse width of 768 µs. l 140 °C (284 °F) = a pulse width of 4848 µs.

Function The coolant temperature signal is an output from the ECM to the instrument cluster. The coolant temperature signal is generated via pin 44 of connector C0636 of the ECM.

The coolant temperature signal can fail in the following ways: l Wiring short circuit to vehicle supply. l Wiring short circuit to vehicle earth. l Wiring open circuit.

In the event of a coolant temperature signal failure any of the following symptoms may be observed: l Coolant temperature gauge will read cold at all times. l Coolant temperature warning lamp remains on at all times.

Controller Area Network (CAN) system

The controller area network (CAN) system is a high speed serial interface between the ECM and the Electronic Automatic Transmission (EAT) ECU. The CAN system uses a 'data bus' to transmit information messages between the ECM and the EAT ECU. Because there are only two components in this CAN system, one will transmit information messages and the other will receive information messages, and vice-versa.

Conditions The CAN system is used by the EAT ECU and the ECM for transmission of the following information: l Gearshift torque control information. l EAT OBD information. l MIL request. l Vehicle speed signal. l Engine temperature. l Engine torque and speed. l Gear selected. l Gear change information. l Altitude adaptation factor l Air intake temperature l Throttle angle / pedal position