Home/Chevrolet/Cab & Chassis R20/Chevrolet Cab & Chassis R20 (1987-1987)/Repair manual/Ccc Tbi Tests W/codes/CODE 55 - ECM PROBLEM

Contents

Section: Ccc Tbi Tests W/codes

MODEL IDENTIFICATION

BASIC DIAGNOSTIC PROCEDURES

ENTERING OR EXITING DIAGNOSTIC MODE

CLEARING TROUBLE CODES

Without "SCAN" Tool

With "SCAN" Tool

TROUBLE CODE DETERMINATION (HARD OR INTERMITTENT)

Diagnostic Charts

System Check

Field Service Mode Check

DIAGNOSTIC TOOLS

Circuit Description

Test Description

Diagnostic Aids

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 ENGINE ONLY)

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

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

CODE 55 - ECM PROBLEM

ECM REPLACEMENT CHECK CHART

Circuit Test Description

A/C Compressor Or Relay Failure

All sections

CODE 55 - ECM PROBLEM Chevrolet Cab & Chassis R20

Ccc Tbi Tests W/codes

CODE 55 - ECM PROBLEM

Be sure ECM grounds are okay and that MEM-CAL, PROM, and/or CALPAK are properly latched. If okay, replace ECM. Clear codes, confirm "Closed Loop" operation, and no "SERVICE ENGINE SOON" light.