Part 2

ELECTRONIC THROTTLE CONTROL INDICATOR

The Electronic Throttle Control (ETC) indicator gives an indication to the vehicle operator when the ETC system, or a circuit or component of the system is ineffective. The ETC indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the PCM over the CAN data bus. The IC will illuminate the ETC indicator for about fifteen seconds as a bulb test each time the ignition switch status transitions to ON.

The ETC indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the ETC indicator for the following reasons:

- ETC Indicator Lamp-On Message - Each time the IC receives an electronic ETC indicator lamp-ON message from the PCM, the ETC indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the PCM message. The indicator remains illuminated solid or continues to flash for about 12 seconds or until the IC receives a lamp-OFF message from the PCM, whichever is longer. If the indicator is illuminated solid with the engine running the vehicle will usually remain drivable. If the indicator is flashing with the engine running the vehicle may require towing. A flashing indicator means the ETC system requires immediate service. The indicator will be extinguished when the ignition switch status transitions to OFF.

The PCM continually monitors the ETC system circuits and sensors to decide whether the system is in good operating condition. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. If the PCM sends a lamp-ON message after the bulb test, it indicates that the PCM has detected an ETC system malfunction or that the ETC system is ineffective. The PCM will store a DTC for any malfunction it detects. Each time the ETC indicator fails to illuminate due to an open or short in the IC ETC indicator circuit, the IC sends a message notifying the PCM of the condition, then the IC and the PCM will each store a DTC.

For proper diagnosis of the ETC system, the PCM, the IC, the CAN data bus or the electronic communication related to ETC indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

ENGINE TEMPERATURE INDICATOR

The engine temperature indicator gives an indication to the vehicle operator when the engine temperature gauge reading reflects a condition requiring immediate attention. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received from the PCM over the CAN data bus. The IC will illuminate the engine temperature indicator for about three seconds as a bulb test each time the ignition switch status transitions to ON.

The engine temperature indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The engine temperature indicator will also be turned ON for the following reasons:

- Engine Temperature High Message - Each time the IC receives a message from the PCM indicating the engine coolant temperature is high, the engine temperature indicator will be illuminated and a single chime tone is sounded. The indicator remains illuminated until a message from the PCM indicating that the engine coolant temperature is below the high end of normal is received, or until the ignition switch status transitions to OFF, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the engine temperature indicator is cycled off and then on again by the appropriate engine temperature messages from the PCM.

The PCM continually monitors the engine coolant temperature sensor to determine the engine operating temperature. The PCM then sends the proper engine coolant temperature messages to the IC. If the IC turns on the engine temperature indicator due to a high engine temperature gauge reading, it may indicate that the engine or the engine cooling system requires service.

ELECTRONIC STABILITY CONTROL INDICATOR

The Electronic Stability Control (ESC) indicator gives an indication to the vehicle operator when the ESC has been activated. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the CAB and the Final Drive Control Module (FDCM) over the CAN data bus. The IC will illuminate the ESC/BAS indicator for about four seconds as a bulb test each time the ignition switch status transitions to ON.

The ESC indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the ESC/BAS indicator for the following reasons:

- ESC Indicator Lamp-On Message - Each time the IC receives an electronic ESC/ indicator lamp-ON message from the CAB indicating that the ESC system has been activated, the ESC indicator will be illuminated. The indicator remains illuminated until the IC receives a lamp-OFF message from the CAB, or until the ignition switch status transitions to OFF, whichever occurs first.
- ESC Off Textual Message - Each time the IC receives an electronic ESC OFF indicator lamp-ON message from the CAB indicating that the ESC system has been manually disabled, an ESC OFF textual message will appear within the IC electronic display unit. The ESC OFF textual message remains displayed until the IC receives a lamp-OFF message from the CAB, or until the ignition switch status transitions to OFF, whichever occurs first.
- ESC Textual Warning Message - When the CAB or FDCM detects certain monitored fault conditions, it will send electronic messages requesting the IC display a textual warning message. Each time the IC receives an electronic ESC textual warning request message from the CAB or FDCM, a WARNING! LIMIT SPEED textual message will appear within the IC electronic display unit to accompany an ESC indicator that is illuminated solid. This message indicates that the CAB or FDCM has detected a problem in one of the ESC system circuits or components.

The CAB and FDCM continually monitor the ESC circuits and sensors to decide whether the system is in good operating condition. The CAB or FDCM then sends the proper lamp-ON or lamp-OFF message to the IC.

For proper diagnosis of the ESC/BAS system, the CAB, the FDCM, the IC, the CAN data bus or the electronic communication related to the ESC/BAS indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

FRONT FOG LAMP INDICATOR

The front fog lamp indicator gives an indication to the vehicle operator whenever the front fog lamps are illuminated. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the BCM over the CAN data bus.

The front fog lamp indicator LED is completely controlled by the IC logic circuit, and that logic will allow this indicator to operate whenever the IC receives a battery current input on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch status. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the front fog lamp indicator for the following reasons:

- Front Fog Indicator Lamp-On Message - Each time the IC receives an electronic front fog indicator lamp-ON message from the BCM indicating the front fog lamps are turned ON, the front fog lamp indicator will be illuminated. The indicator remains illuminated until the IC receives a lamp-OFF message from the BCM, or until the exterior lamp load shedding (battery saver) timed interval expires, whichever occurs first.

The BCM continually monitors a hard wired input from the exterior lighting switch to determine the appropriate outputs to the front fog lamps. The BCM activates or deactivates the front fog lamps then sends the proper lamp-ON or lamp-OFF message to the IC to control the front fog lamp indicator.

For proper diagnosis of the front fog lamp system, the BCM, the IC, the CAN data bus or the electronic communication related to front fog lamp indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

GAS CAP INDICATOR

The gas cap indicator gives an indication to the vehicle operator when there is a gross leak detected in the on-board fuel vapor recovery system. This indicator is controlled by the IC logic circuit based upon programming and electronic messages received over the CAN data bus from the PCM.

The gas cap indicator function of the IC electronic display unit is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the gas cap indication will always be OFF when the ignition switch status is anything except ON or START. The IC will turn ON the gas cap indicator for the following reasons:

- Gas Cap Indicator Lamp-On Message - Each time the IC receives an electronic gas cap indicator lamp-ON message from the PCM indicating there is a gross leak in the vapor recovery system, the gas cap indicator will be displayed. The indicator remains displayed until the IC receives a lamp-OFF message from the PCM, until the IC arbitrator logic determines that another display request has priority, or until the ignition switch status transitions to OFF, whichever occurs first.
NOTE: If the On-Board Diagnostic (OBD) system in the vehicle determines that the fuel filler cap is loose, improperly installed or damaged, a gas cap ICON will be displayed in the electronic display unit. In this instance, verify that the gas cap is properly installed and tightened before proceeding with any further diagnosis.

The PCM continually monitors the on board vapor recovery system to determine whether there are air leaks in the system. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. If the IC turns ON the gas cap indicator due to a monitored gross leak in the vapor recovery system, it may indicate that the gas cap has been removed or is improperly installed.

For proper diagnosis of the on board vapor recovery system, the PCM, the IC, the CAN data bus or the electronic communication related to gas cap indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

HIGH BEAM INDICATOR

The high beam indicator gives an indication to the vehicle operator whenever the headlamp high beams are illuminated. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received from the BCM over the CAN data bus.

The high beam indicator LED is completely controlled by the IC logic circuit, and that logic will allow this indicator to operate whenever the IC receives a battery current input on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch status. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the high beam indicator for the following reasons:

- High Beam Indicator Lamp-On Message - Each time the IC receives an electronic high beam indicator lamp-ON message from the BCM or the Automatic High Beam Module (AHBM) (also known as SmartBeam(R) on vehicles so equipped) the high beam indicator will be illuminated. The high beam indicator remains illuminated until the IC receives a lamp-OFF message from the BCM, or until the exterior lamp load shedding (battery saver) timed interval expires, whichever occurs first.

The BCM continually monitors electronic messages from the Steering Angle Sensor (SAS) based upon the status of the beam select switch and the AHBM to determine the proper headlamp beam control. The BCM activates or deactivates the headlamp high beams then sends the proper lamp-ON or lamp-OFF message back to the IC.

For proper diagnosis of the SAS, the AHBM, the BCM, the IC, the CAN data bus or the electronic communication related to high beam indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW COOLANT INDICATOR

The low coolant indicator gives an indication to the vehicle operator when the diesel engine coolant level is low. This indicator is controlled by the IC logic circuit based upon programming and electronic messages received over the CAN data bus from the PCM.

The low coolant indicator function of the IC electronic display unit is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the low coolant indication will always be OFF when the ignition switch status is anything except ON or START. The IC will turn ON the low coolant indicator for the following reasons:

- Low Coolant Indicator Lamp-On Message - Each time the IC receives an electronic low coolant indicator lamp-ON message from the PCM indicating the engine coolant level is low, the low coolant textual warning and icon are illuminated and a single chime tone is sounded. The low coolant textual warning and icon remain illuminated until the IC receives a lamp-OFF message from the PCM, or until the ignition switch status transitions to OFF, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the textual warning and icon are cycled OFF and then ON again by the appropriate messages from the PCM.

The PCM continually monitors the engine coolant level switch on the coolant bottle to determine the level of the engine coolant. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. If the IC turns ON the coolant low indicator and icon due to a low coolant level, it may indicate that the engine or the engine cooling system requires service.

For proper diagnosis of the engine coolant level switch, the PCM, the IC, the CAN data bus or the electronic communication related to low coolant indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW FUEL INDICATOR

The low fuel indicator gives an indication to the vehicle operator when the level of fuel in the fuel tank becomes low. This indicator is controlled by a transistor on the IC circuit board based upon programming and a hard wired input received by the IC from the fuel level sending unit on the fuel pump module in the fuel tank. The IC will illuminate the low fuel indicator for about three seconds as a bulb test each time the ignition switch status transitions to ON.

The low fuel indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the low fuel indicator for the following reasons:

- Less Than 11 Percent Tank Full Input - The BCM provides a constant current source to the fuel level sending unit, and monitors a return input on a fuel level sense circuit. The resistance through the fuel level sending unit increases as the fuel level falls, and decreases as the fuel level rises causing changes in the sense input voltage. Each time the fuel level sense input to the BCM indicates the fuel tank is about 11 percent full or less for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, the BCM sends an electronic message to the IC. Then the IC moves the gauge needle to the appropriate position on the gauge scale; the low fuel indicator is illuminated and a single chime tone is sounded. The low fuel indicator remains illuminated until the fuel level sense input indicates that the fuel tank is greater than about 14 percent full for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, or until the ignition switch transitions to OFF, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the low fuel indicator is cycled OFF and then ON again by the appropriate inputs from the fuel level sending unit.
- Less Than Empty Stop Input - Each time the IC receives a fuel level message from the BCM that indicates the fuel level in the fuel tank is less than the E (or Empty) gauge needle stop position for five consecutive seconds, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the BCM is a short circuit.
- More Than Full Stop Input - Each time the IC receives a fuel level message from the BCM that indicates the fuel level in the fuel tank is more than the F (or Full) gauge needle stop position for five consecutive seconds, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the BCM is an open circuit.

The BCM continually monitors the fuel tank sending unit to determine the level of fuel in the fuel tank. The BCM then sends the proper electronic fuel level message to IC and other electronic modules in the vehicle over the CAN data bus. The BCM will store a DTC for any fault detected in the fuel level sense circuit.

For proper diagnosis of the fuel tank sending unit, the BCM, the IC, and the CAN data bus or the electronic communication related to low fuel indicator operation or fuel level data processing, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW OIL PRESSURE INDICATOR

The low oil pressure indicator gives an indication to the vehicle operator when the engine oil pressure reading reflects a condition requiring immediate attention. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the PCM over the CAN data bus.

The low oil pressure indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the low oil pressure indicator for the following reasons:

- Engine Oil Pressure Low Message - Each time the IC receives an electronic engine oil pressure message from the PCM indicating the pressure is about 6.9 kPa (1 psi) or lower, the low oil pressure indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the PCM message. The indicator remains illuminated solid or flashing until the IC receives a message from the PCM indicating that the pressure is above about 6.9 kPa (1 psi), or until the ignition switch status transitions to OFF, whichever occurs first. The IC will only turn the indicator ON in response to low engine oil pressure if the engine speed is greater than zero.

The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper messages to the IC. If the IC turns ON the indicator after the bulb test, it may indicate that the engine or the engine oiling system requires service.

For proper diagnosis of the engine oil pressure sensor, the PCM, the IC, the CAN data bus or the electronic communication related to low oil pressure indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.