SERVICE MANUAL UPDATE SEC. 8A DIGITAL I/P CLUSTER REVISED

SUBJECT: SMU - SECTION 8A ELECTRICAL DIAGNOSIS - REVISED DIGITAL CLUSTER U2A INFORMATION

VEHICLES AFFECTED: 1991-92 "C" AND 1992 "H" MODELS

* THIS BULLETIN IS BEING REVISED TO CORRECT PREVIOUSLY RELEASED INCORRECT DIAGNOSTIC INFORMATION.

Please discard the previously mentioned Bulletin dated October 31,1991 and use the following revised symptom/diagnosis chart to correct a metric only display problem on affected domestic vehicles.

INSTRUMENT SYMPTOM DIAGNOSIS CLUSTER ------- --------- ---------- ANALOG (U2E) HVAC Programmer displays external 1. Check HVAC Programmer or set temperature in degrees connector terminal C6 Celsius for a BLK wire. If a wire is present, cut it, tape ends to prevent shorts, and then tape it back to wiring harness. If wire is not present, replace HVAC Programmer. ----------------------------------------------------------------------------

GAGES (UB7) IPC E/M button does not change HVAC 1. Disconnect Instrument Programmer temperature display Cluster connector C1. Put between F and C; but button does Ignition Switch in RUN, change DIC information between turn on Air Conditioning, English and metric values and observe HVAC Temperature. ---------------------------------------------------------------------------- DIGITAL (U2A) IPC E/M button does not change HVAC Programmer temperature - If temperature is in F, display between F and C; but go to step 2. button does change both IPC gages and DIC information - If temperature is in C, between English and metric check LT BLU (81 1) wire values. for a short to ground. --------------------------- Also check that export ground, BLK (154) wire, IPC E/M button does not change has not been included at HVAC Programmer temperature terminal C6 of HVAC display between F and C, or Programmer. or IPC Gages between English and metric values; but button - If a wire is present, does change DIC information cut it, tape ends to between English and metric prevent shorts, and then values tape it back to wiring harness. Also check continuity between HVAC Programmer connector terminal C6 and Instrument Cluster connector C1 terminal A3. If an open circuit is found, install a .5 LT BLU wire between the two terminals using Terminal Repair Kit J 38125-A.

2. With Ignition Switch in RUN, connect a fused jumper between Instrument Cluster connector C1 terminal A3 and ground. Observe HVAC display.

- If temperature is displayed in C, replace Instrument Cluster.

- If temperature is not displayed in C, check LT BLU (811) wire for an open between HVAC Programmer connector terminal C6 and Instrument Cluster connector C1 terminal A3. Repair as necessary. If OK, replace HVAC Programmer.

--------------------------------------------------------------------------- GAGES (UB7) or IPC E/M button does not change 1. Replace Instrument DIGITAL (U2A) DIC information between English Cluster. and metric values

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.