SERVICE MANUAL UPDATE SEC. 8A INSTR. PANEL DIAGNOSIS (STE). Pontiac 6000 1988

Models Affected: 1988 6000 STE

The following page should replace the current page in the specified Manual.

INSTRUMENT PANEL: DIGITAL CLUSTER

H: TEMPERATURE GAGE SHOWS HOT

Remove the connector from the Coolant Temperature Sender and turn the Ignition Switch to RUN.

If the display is now blank, the wiring is good. Do Test M.

If the display still shows hot, check for a short to ground in the DK GRN/WHT (35) wire back to the Instrument Cluster. If that wire is good, replace the Instrument Cluster (see Section 8C).

I: TEMPERATURE GAGE IS INACCURATE OR IS BLANK

Remove the connect from the Coolant Temperature Sender. Connect one red clip lead of the J-33431 tester to the harness connector terminal and the other red clip lead to ground. Adjust the resistance dials of the tester to 912 +/- 109 ohms and then to 85 ohms. The Temperature Display should show low temperature, approximately 120 DEG F (49 DEG C) and then hot 260 DEG F (127 DEG C).

If the display is correct, the cluster is good. Install a new Coolant Temperature Sender.

If the display is not correct, check the DK GRN/WHT wire for an open or high resistance. If the wire is OK, replace the Instrument Cluster (see Section 8C).

J: SPEEDOMETER AND ODOMETERS ARE INACCURATE (J33431 -10 Harness Connector Available)

Disconnect Electronic Control Module connector C2. Plug in the J-33431 Instrument Panel Cluster Tester and connect the J33 431-10 Harness Connector to C2 terminal Bll. Turn the Ignition Switch to RUN. Set the tester con- trols to ON, 54 MPH and 60 Hz. The Speedometer should indicator 54 +/- 2 MPH.

If the Speedometer reads correctly, check for correct tire size and inflation. If OK, replace Electronic Control Module.

If the Speedometer does not read correctly, replace the Instrument Cluster (see Section 8C).

K: SHIFT INDICATOR TEST

Connect: FUSED JUMPER

At: CONNECTOR C210 (MALE HALF)

(Disconnected)

CONDITION:

Ignition Switch: RUN

Jumper Correct Result For Diagnosis Between ------- -------------- -------------- H (TAN/BLK) SHIFT &Ground Indicator See 1 lights Remove Jumper

Jumper SHIFT Removed Indicator goes See 2 out

If the results are correct, check the TAN/ BLK (456) wire to the ECM for an open or a short to ground. If the wire is OK, see Section 6E for ECM diagnosis.

1. Check TAN/BLK (456) wire from the Instrument Cluster for an open. If the wire is good, replace the Instrument Cluster (See Section 8C).

2. Check TAN/BLK (456) wire from the Instrument Cluster for a short to ground. If the wire is OK, replace the Instrument Cluster (see Section 8C).

CIRCUIT OPERATION

Audible Alarm and Gages

With the Ignition Switch in RUN, voltage is applied through the FAN/ELEC Fuse to the Battery Power Input terminal of the Gages Module in the Instrument Panel Digital Cluster. With the Light Switch in PARK or HEAD, voltage is applied at all times to the Lights-On Dim Input.

English/Metric Switch

The English/Metric Switch, located in the Display Switch Assembly, by-passes either one of the two light emitting diodes. In the Metric position, the E diode is shorted out and the E diode is conducting and glowing. Battery volt- age is also applied to the English/Metric Input of the Digital Cluster to connect the solid state processor to Metric readouts.

With the Switch the English position, the E diode is by-passed. The E diode conducts and glows. The English/Metric Input to the Digtial Cluster is now grounded.

Fuel Display

The Fuel Gage Sender provides a signal to the cluster that is related to fuel level. With a full tank, the resistance is 90 ohms, and with an empty tank, the resistance is less than 1 ohm.

The microprocessor converts this signal and activates a 16-segment bar-graph which displays the fuel level. Each segment corresponds to one gallon of fuel. When the bar-graph Fuel Display changes from two segments to one, the Audible Alarm sounds briefly and the Low Fuel Warning Indicator lights.

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.