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Contents

Section: Ccc Tbi Tests W/codes

MODEL IDENTIFICATION

BASIC DIAGNOSTIC PROCEDURES

CLEARING TROUBLE CODES

Without "SCAN" Tester

With "SCAN" Tester

TROUBLE CODE DETERMINATION (HARD OR INTERMITTENT)

Diagnostic Charts

System Check

Field Service Mode Check

DIAGNOSTIC TOOLS

Circuit Description

Test Description

Diagnostic Aids

Fuel Module Check Procedure

System Too Lean (High Air/Fuel Ratio)

System Too Rich (Low Air/Fuel Ratio)

Throttle Body

A/C Compressor Relay Failure

O2 Sensor Wire

Fuel Contamination

Fuel Pressure

AIR System

Circuit No. 413

Sensor Harness

HEI Shielding

Canister Purge

MAP Sensor

Pressure Regulator

TPS

CODE 51 - FAULTY MEM-CAL (2.5L)

CODE 51 - PROM PROBLEM (2.8L/4.3L/5.0L/5.7L/7.4L)

CODE 52 - FUEL CALPAK MISSING (2.8L/4.3L/5.0L/5.7L/7.4L)

CODE 53 - SYSTEM OVER VOLTAGE (2.5L)

CODE 55 - ECM PROBLEM (2.8L/4.3L/5.0L/7.4L)

Circuit Test Description

A/C Compressor Or Relay Failure

All sections

System Check GMC Cab & Chassis K2500

Ccc Tbi Tests W/codes

System Check

If complaint is "SERVICE ENGINE SOON" light related, this check will lead to the most likely problem area (if a malfunction exists). Enter diagnostic mode by grounding terminal "B" of ALDL connector and record stored trouble codes.
Begin diagnosis with the lowest numbered code shown and go to the numbered trouble code chart. If code "51" is displayed, see PROM or MEM-CAL removal and installation in this article.