Instrument Cluster Operation Without Electric Compass

Instrument Cluster

The instrument cluster is centered above the steering column in the instrument panel. The instrument cluster is removable from the rear of the panel (toward the steering wheel). The cluster contains instruments that provide the driver with information on vehicle performance.

The instrument cluster includes the following components:

The vehicle speed reading on the speedometer is shown in both English (mph) and metric (km/h). The coolant temperature gauge omits any numerical readout markings and only contains a range of hash marks between C and H. The instrument cluster also contains numerous indicator lamps.

The instrument cluster assembly contains the cluster lens, and the speedometer/tachometer gauge module. The electric power is directed to each gauge through flexible printed circuits to each gauge module. The instrument cluster is serviceable as both a unit and as individual components (each gauge module may be removed from the cluster). The individual gauge modules are not to be disassembled.

When an instrument cluster is replaced, the law requires either the odometer reading of the replacement unit be set to register the original mileage or that a label be installed on the driver's door frame to show the previous odometer reading and the date of replacement. Since the mileage can NOT be set on the odometer in this vehicle, an odometer label must be used.

Instrument Cluster Service Precautions

Important: In testing for opens or shorts, do not ground or apply voltage to any of the instrument cluster circuits, unless you are instructed to do so by the diagnostic procedures.

The instrument cluster is designed in order to withstand normal current drains associated with vehicle operations. Avoid overloading any circuits. Only test these circuits using the J 39200 DMM. Refer to

Notice: Electrostatic discharge (ESD) can damage many solid-state electrical components. ESD susceptible components may or may not be labeled with the ESD symbol. Handle all electrical components carefully. Use the following precautions in order to avoid ESD damage:

•	Do not touch exposed terminals. Terminals may connect to circuits susceptible the ESD damage.

•	Do not allow tools to contact exposed terminals when servicing connectors.

•	Do not remove components from their protective packaging until required to do so.

•	Avoid the following actions unless required by the diagnostic procedure:

-	Jumpering or grounding of the components or connectors.

-	Connecting test equipment probes to components or connectors. Connect the ground lead first when using test probes.

•	Ground the protective packaging of any component before opening. Do not rest solid-state components on metal workbenches, or on top of TVs, radios, or other electrical devices.

in Cautions and Notices.

Diagnostic System

The instrument cluster is equipped with an extensive diagnostic system that is capable of performing the following functions:

When a malfunction is detected, the instrument cluster performs one or both of the following actions:

Diagnostic Trouble Codes (DTCs)

The DTCs when set, indicate that the instrument cluster has detected a malfunction in a particular circuit or other system. The instrument cluster is programmed with routines for internal tests that the instrument cluster follows only under prescribed conditions (test conditions). When these conditions exist, the instrument cluster tests certain circuits or systems for a malfunction (failure conditions). When the failure conditions are true, a DTC is set current. Some DTCs command the instrument cluster to illuminate the SERVICE VEHICLE SOON indicator.

The DTCs are not stored in the instrument cluster's electrically erasable programmable read only memory (EEPROM). The DTCs are not retained after a battery disconnect.

Current DTCs

When the instrument cluster determines that the conditions for a DTC are present, the instrument cluster sets that DTC as current. All DTCs remain current until the next time the instrument cluster finds the conditions to set the DTC are no longer current. Some DTC's remain current after the conditions for setting it are no longer present until the next ignition cycle.

History DTCs

After the instrument cluster determines that the conditions for setting a DTC are no longer present it changes it to a history DTC. Some DTC's remain as current after the conditions for setting the DTC are no longer present until the next ignition cycle.

Instrument Cluster EEPROM

Important: The EEPROM is soldered into the instrument cluster. You can not service the EEPROM separately.

The instrument cluster contains a data storage device that can save critical data even when battery power is removed. This device is called the electrically erasable programmable read only memory (EEPROM). The EEPROM is used by the instrument cluster in order to store the following information:

Instrument Cluster Keep Alive Memory (KAM)

The instrument cluster contains a data storage area that saves pertinent data when the ignition is turned OFF. The data is lost when the battery power is removed. The data storage area is called the KAM. The instrument cluster uses the KAM in order to store the following information:

Dimming

The instrument cluster displays are dimmable. The indicators are non-dimmable. The instrument cluster backlighting (graphics and pointers) is directly controlled by the dash integration module (DIM) via the IP dimmer switch. The instrument cluster receives the dimming status via a class 2 message from the DIM.

Instrument Cluster Operation Pontiac with Electric Compass

The electronic compass is available as part of the instrument cluster assembly. The electronic compass system is factory installed. The system consists of the following components:

The compass display is located in the instrument cluster. The display is to the left of the gauges. The compass display indicates the vehicle heading. The compass has a directional display. The display has symbolic horizontal and road lines. In addition, word and symbol displays are provided. The word and symbol displays are for use in the following functions:

The electronic compass module includes the following components:

The sensor sends input to the microprocessor. The microprocessor provides output to the compass display within the instrument cluster. The compass operates on the same principle as other fluxgate compasses. The sensor measures direction by measuring the earth's magnetic strength in two perpendicular coils. The coils are part of the fluxgate sensor. The fluxgate sensor converts the magnetic strength into electrical signals that the cluster can understand.

The vehicle heading is sent to the compass display via circuit 336 (PPL/WHT). The electronic compass module sends the vehicle heading only when requested by the compass display. When the compass display receives the heading information, the information is converted into a display format. The display format is shown on the compass display.

The clock input on circuit 337 (TAN/WHT) is a timing signal. The signal keeps the electronic compass module and the compass display communicating at the right time and rate. The clock signal must function in order for data to be exchanged between the module and the display. The compass display receives VSS input on circuit 817 (DK GRN).

Magnetic North is not always the same as geographical north. Refer to Variation Mode.

No periodic service or maintenance is required on the compass system. Once the compass has been properly calibrated, the system should not require adjustment other than updating the zone number if you drive the vehicle to a new zone.

The electronic compass module must be sensitive. Many things can affect the compass module's ability to measure accurately the earth's magnetism. The following commonly found factors may affect the compass' accuracy:

Power Up Display Sequence

When you turn the ignition switch to RUN, all segments of the display light for about 3 seconds. The compass display then displays the current vehicle heading and current zone. After a few seconds, the zone display turns off. The displayed vehicle heading is the last heading displayed when the ignition switch was turned OFF.

Heading Mode

The heading mode is the normal operating mode of the compass. The mode shows the direction that the vehicle is heading. The vehicle heading does not change if the vehicle is not moving. The compass display receives VSS information in order to determine the vehicle speed. While in the heading mode, you may select one of the following odes:

If the actual heading changes dramatically, such as during a hard turn, the display may slow down in order to prevent a false heading reading.

The auto-calibration feature works continuously while in the heading mode. This feature keeps the compass calibrated over the life of the vehicle. The feature adjusts for small changes in the vehicle's magnetism which occur over time. The auto-calibration feature makes repeated manual calibration unnecessary.

While the system is in the heading mode, if a malfunction occurs, the word CALIBRATE displays until one of the following conditions is met:

If calibrate displays after the compass has been working properly, a strong disturbance in the signal may be present.

Variation Mode

Magnetic north is not always the same direction as geographic north. For accurate heading mode displays, the difference between magnetic north and geographic north must be stored in the compass system. This angular separation is represented by a zone number. The zone numbers are found on the map.

The variation should be set for the correct zone before delivery of the vehicle to the customer. If the vehicle is driven to a new zone, you should update the none number. Use the following procedure in order to set the variation:

1. Press and hold the MODE button until the word ZONE and the zone number display for one second.
2. Release the MODE button.
3. Press the MODE button until the desired zone number is displayed.

After 5 seconds, ZONE and the zone number turn off. The electronic compass module remembers the new zone number. If the ignition switch is turned to OFF before ZONE turns off, the new zone number is not saved. A battery disconnect does not erase the zone number from the electronic compass module memory.

Manual Calibration Mode

Manual calibration is normally needed only if the electronic compass module is new and has never been calibrated for the vehicle. Perform manual calibration if the direction bars are turned off and CALIBRATE is shown on the display. When CALIBRATE displays, the electronic compass module has detected a strong magnetic field and cannot show the proper heading.

Use the following procedure in order to perform manual calibration:

1. Turn the rear defogger off.
2. Press the MODE button until CALIBRATE displays. You will step through the variation mode for about 3 seconds before you reach the manual calibration mode.
3. Release the MODE button. The direction bars start to rotate.
4. Drive the vehicle in small circles. Do not drive faster than 10 mph.
5. Drive the vehicle in small circles until the CALIBRATE display turns off. The display will turn off after about 1-5 circles.

The compass is now calibrated. Calibration is confirmed when the CALIBRATE display turns off. The direction bar shows the true vehicle heading.

If you do not release the MODE button after the CALIBRATE display turns on, the display returns to the heading mode in a few seconds. Also, you may cancel the calibration mode by either of the following methods:

If the rear defogger is on, the following actions occur:

These actions indicate that the electronic compass module can not enter manual calibration mode. After 5 seconds, CALIBRATE stops flashing and the compass display returns to the heading mode.

If you enter manual calibration mode and you do not move the vehicle within a few minutes, the following actions occur:

These actions indicate that the electronic compass module is returning to the heading mode. The old calibration values are retained.

If the CALIBRATE display flashes and chime sounds after you drive the vehicle in circles while in calibration mode, refer to