DIGITAL CLUSTER GOES BLANK OR SPEEDOMETER READ 188 W/HORN

SUBJECT: DIGITAL CLUSTER GOES BLANK OR SPEEDOMETER READS 188 WHEN HORN IS DEPRESSED (INSTALL HORN KIT) -

VEHICLES AFFECTED: 1993 "S/T" WITH RPO U52

CONDITION:

--------- Some 1993 S/T trucks with RPO U52 Digital IP Clusters may experience an intermittent blank IP cluster or a reading of 188 on the speedometer display when the ignition is on and the horn is depressed.

CAUSE:

----- This condition is caused by a voltage spike in the horn circuit when the horn is actuated.

CORRECTION:

---------- To correct this condition engineering has released two service horn kits that have built in electrical suppression. Vehicles have been corrected in production after the following VIN'S:

Pontiac West GMC P0513648 Chevrolet P0145373

Moraine GMC P2523127 Chevrolet P2159574 Oldsmobile P2706084

Shreveport GMC P8519090 Chevrolet P8179203

SERVICE PROCEDURE:

1. Disconnect and remove "F" note horn from the left radiator support.

2. Assemble "F" note horn and bracket from Horn Kit P/N 10456443.

3. Install and connect the horn.

4. Disconnect and remove "A" note horn from the left inner fender. a. T-Truck - Remove the oil filter. If equipped with an L35 engine, remove the air cleaner assembly.

5. Assemble "A" note horn and bracket from Horn Kit P/N 10456328.

6. Install and connect the horn.

7. Reinstall the oil filter and remote air cleaner, if necessary.

8. Check and add oil as required.

SERVICE PARTS INFORMATION

Part Number Description Qty ----------- ----------- --- 10456328 Horn Kit "A" Note 1 10456443 Horn Kit "F" Note 1

WARRANTY INFORMATION

For vehicles repaired under warranty, use:

Labour Operation Description Labour Time ---------------- ----------- ----------- N0200 Horn Assemblies, Replace See applicable S-Truck Labour Time Guide T-Truck

Add: With L35 engine and remote air cleaner.

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.