ELECTRONIC CLUSTER-U52 REPAIR (INDICATOR AND GAUGE SYMPTOMS)
VEHICLES AFFECTED: 1987-88 BARRETTA
1. Fuel Gauge Blanks Out When The Tank Is Completely Full
Condition:
---------- The fuel gauge will blank out (show empty), and the pump symbol may flash, when the tank is completely full. When the level of the tank drops slightly (usually after 40 to 50 kilometres of driving), the gauge will show full and operate normally.
Cause:
------ The cluster has built-in diagnostics that cause the gauge to blank and flash when an open circuit is detected. The calibration of the set point is close enough to the maximum output of the sender that some senders may cause this condition.
Correction:
----------- This condition may be corrected by adding a resistor in parallel with the sender wire by using the following procedure:
1. Disconnect negative battery cable.
2. Remove lower rear seat cushion (retained by two bolts under the front edge of the seat). Pull the insulation mats on the left side out of the way.
3. Open the conduit on the left side of the vehicle and locate and pull out the pink wire and one of the black wires (Figure 1). Strip about 1/2" of insulation from the pink wire, then solder one end of a 2000 ohm, 1/4 watt resistor to the pink wire. Then strip the black wire, and solder the other end of the resistor to it. Tape the wires and resistor, and place back into the conduit.
The resistor can be obtained from an electronics supply outlet, such as Radio Shack.
NOTICE: THE RESISTOR MUST BE SOLDERED IN PLACE! ANY OTHER TYPE OF CONNECTION WILL NOT CORRECT THE CONDITION PERMANENTLY.
4. Replace lower rear seat cushion, and connect negative battery cable.
2. Incorrect "Average Fuel Economy", "Instantaneous Fuel Economy" and "Range" Readouts.
The fuel economy readouts will register approximtely 30% low. This condition is caused by an incorrect value in the ECM MEMCAL, and no attempt should be made to repair the cluster. New ECM MEMCAL part numbers are:
16128927 Automatic Trans. (Federal) 16128928 Manual Trans. (Federal)
Replace the ECM MEMCAL using the followi-ng installation procedure:
(a). Disconnect battery power. (b). Install new ECM MEMCAL calibration. (c). Reconnect battery power. (d). Start vehicle with AC/defroster off and power steering not cramped. (e). Allow vehicle to idle in drive for 6 minutes and until thermostat has opened. This will facilitate learning of base idle. (f). Return vehicle to service.
NOTICE: DO NOT REPLACE THE MEMCAL AND RETURN THE VEHICLE TO THE CUSTOMER WITHOUT PROPERLY COMPLETING THE ABOVE STEPS.
3. Inoperative "Upshift" Light
On 1988 manual transmission vehicles built after VIN 500,000, the "upshift" light may be inoperative. Check the rear of the cluster to insure that a bulb is installed. If not, add bulb, P/N 25085641, in the proper receptacle (just behind the "upshift" lens.)
Note: 1987 vehicles, and 1988 vehicles built before VIN 500,000 do not use an upshift light.
4. Part of the Cluster Display Is Inoperative.
The cluster needs backlight illumination to work properly. If one of the bulbs is burned out, part of the cluster will appear dark. There are four (4) bulb and socket assemblies P/N 25085672, on the bottom of the cluster, which can be replaced at the dealership.
Do not return the cluster for repair of a burned out bulb.
5. Scratched Lens or Mask.
The lens and the mask under the lens are available from GMSPO. Part numbers are:
Lens: 25087811
Mask: 25088094
Do not return the cluster for repair of a scratched lens.
6. A regular function of the cluster is to display the RANGE reading when the range drops below 50 miles. This is intended as a low fuel warning. Some customers may not be aware of this feature, since the Electronic Cluster information was not included in some of the early Owner's Manual.
The electronic cluster information from the Owner's Manual is attached, and may be copied and given to the customer. Or, you may provide the customer with a new Owner's Manual through normal channels.
TURN-ON SEQUENCE
When the ignition key is initially placed in the "RUN" position, all display graphics and gage telltales will remain off for 1 second, then all display graphics (except bar graphs, turn signals and high beam) including gage telltales will light. All graphics and gage telltales will remain on then return to current status display.
INSTRUMENT - GAGE FUNCTION
Speedometer
The speed at which you are traveling is shown in digital or bar graph form. The display readout is given in English or Metric by selection of the English/Metric switch.
Battery Voltage Display
The battery voltage display is an analog readout 13 segment bar graph with markings for 8 to 18 volts. System voltage will vary depanding on electrical load and traffic conditions. A display reading continuously high or low indicates an electrical system failure. The display symbols or bar are designed to flash as a warning. Cause of the failure should be determined and corrected.
Engine Coolant Temperature Display
The engine coolant temperature display is an analog readout, 13 segment bar graph, with markings for cool "C" and hot "H". Coolant temperature indication will vary with air temperature and operating conditions. The display symbols and bar are designed to flash if an overheat condition occurs. Immediate action is required to correct this condition. See "Engine Cooling System Overheating" in Section 3.
Oil Pressure
The oil pressure display is an analog readout, 13 segment bar graph with markings for low "L" and high "H". The oil pressure reading indicates the pressures at which oil is being delivered to various parts of the engine requiring lubrication. The pressure registered may vary according to outside temperature or weight of oil being used. Oil pressure of a cold engine being operated at a given speed will be somewhat higher than when the engine is at normal operating temperature at the same speed. Prolonged high speed operation on a hot day at the given speed will result in somewhat lower oil pressure readings. Readouts that are consistently high or low under these conditions may indicate lubrication system and/or engine malfunction. The symbols and bar are designed to flash with a low pressure reading.
Fuel Display
The fuel gage display is an analog readout 13 segment bar graph with markings from E, empty and F, full. Low fuel is indicated by the flashing of the last two bars ofthe fuel display. This display is not affected by pressing the English/Metric button.
Tachometer
The tachometer indicates the spead of the engine in revolutions per minute. The indicated number times 1000, gives the engine speed. Operating the engine with the tachometer reading in the color-coded high-speed area could lead to serious engine damage. For a digital readout, push the "TEMP/TACH" button on the right just below the cluster. This readout will display in place of the odometer. Also see 'DRIVER INFOMATION CENTER" in this section.
WARNING
Lights and Indicator Lights ----------------------------------- Functional explanation of the balance of the warning and indicator lights is called out previously in this section of the Owner's Manual.
OPTIONAL ELECTRONIC CLUSTER (V6 ENGINE)
DRIVER INFORMATION CENTER
On the right side of the electronic instrument cluster is the Driver Information Center. This will display readouts, in place of the odometer, based on your selection of the switches located just below the cluster. Information can be displayed in English or Metric. A button with two modes will display the second mode with an additional push of the button. To return to the odometer display, simply push the "ODO/TRIP" button.
Outside Temperature
The outside temperature display is a digital readout. This readout will display current outside temperature in English or Metric by selection of the last input of the English/Metric switch. Push the "TEMP/TACH" button to activate.
Odometer/Trip Odometer Indicator -------------------------------- The odometer display is a multi-function display which includes total odometer and trip odometer indicators, tachometer, outside temperature, instant/average fuel economy and range. All of the displays are button selectable and formatted in the same digital display.
Press the ODO/TRIP button, located on the lower right of the instrument cluster, (see illustration) to change odometer display to trip odometer. Press again to change back to odometer function.
To reset the trip odometer to zero, press the RESET button, for one to two seconds, located next to the ODO/TRIP button. The RESET button is functional only when in trip display mode.
The total odometer displays the total number of miles or kilometers the vehicle has traveled. If odometer tampering exists or if the odometer curcutity is defective the odometer will go blank.
The trip odometer displays in digital form to a tenth of a unit, the total number of miles or kilometers traveled since the last reset. It will record mileage traveled in whole and tenths of numbers until it reaches 9,999.9. This will prove useful in recording extended trip mileage and during sports car rallies.
Fuel Economy (INS/AVG) ---------------------- Depending on the function button selected, the display area will display either "instant fuel" economy or "average fuel" economy. The calculation for the fuel economy depends upon fuel consumed and distance traveled in a particular time period. If you display "average fuel" economy, the reset button will initialize the time period, hold the button for one to two seconds. Average fuel economy readout is displayed in whole numbers and tenths. The readout can be displayed in either English (miles per gallon) or Metric (liters per 100 km).
Range
This button will display range based on average fuel economy and fuel remaining. A range of less than 50 miles (80 km) will display automatically every five minutes. Readouts are given in either English or Metric units by selection on the English/Metric button.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
