EXPERTEC TSB (90-222-6E)
Reference number: 90-222-6E
EXPERTEC TSB
TECHNICAL SERVICE BULLETIN
SERVICE MANUAL UPDATE - SEC. 6E-3 CHART A-5 CODES 12, 13 & 14
Model(s): 1990 Geo Prizm
Section: 6E - Engine Fuel & Emission
Bulletin No.: Chevrolet 90-222-6E
Date: 04/11/1990
VEHICLES AFFECTED
Vehicles with 1.6L GSI (VIN CODE 5) Engine
SERVICE INFORMATION
This bulletin serves to revise Chart A-5, Code 12 and/or 13, and Code 14 Facing Page and Chart in Section 6E3-A "Driveability And Emissions" in the 1990 Geo Prizm 1.6L GSI (VIN 5) "S" Carline (PORT) Service Manual. The title block on Pages 6E3-A-1, 6E3-A-26, and 6E3-A-27 are incorrectly labeled. The malfunction Code 12 and 13 is incorrect. Code 12 and 13 should read: Code 12 and/or 13. The attached pages reflect the correct labeling of the malfunction codes and the table of contents page at the beginning of Section 6E3-A.
Revised pages are listed below:
Page 6E3-A-1-Table of Contents
Page 6E3-A-16-Chart A-5 facing page
Page 6E3-A-17 -Chart A-5 chart
Page 6E3-A-26 -Code 12 and/or 13 facing page
Page 6E3-A-27 -Code 12 and/or 13 chart
Page 6E3-A-28 -Code 14 facing page
Page 6E3-A-29 -Code 14 chart
SECTION A - 1.6L (VIN 5) "S" CARLINE (PORT)
Diagnostic Circuit Check
The "Diagnostic Circuit Check" verifies that the engine control system is functioning correctly. Special considerations to observe while performing the "Diagnostic Circuit Check" are:
Blocking Drive Wheels
The vehicle drive wheels should always be blocked while checking the system.
Cold Oxygen Sensor
The system oxygen sensor may cool off after only a short period of operation at idle. This will cause the system to enter "Open Loop" operation. Run the engine at part throttle until "Closed Loop" operation is restored.
BASIC PROCEDURE
If the basic information on using the diagnostic procedures contained in this section has not been reviewed, refer to the introduction of this section.
CHART A-5 - ENGINE CRANKS BUT WILL NOT RUN (FUEL SYSTEM ELECTRICAL TEST) 1.6L (VIN 5) "S" CARLINE (PORT)
Circuit Description
When the engine is cranked the signal from starter will turn "ON" the circuit opening relay to operate the fuel pump. Once the engine has started, the starter signal is removed from circuit opening relay and the fuel control switch in MAF sensor continues to run fuel pump. If the fuel control switch in the MAF sensor is nonfunctional, the engine will start but will not stay running.
Test Description
Numbers below refer to circled numbers on the diagnostic chart.
- Fuel pump should run when ignition is cranked.
- Test for B+ from circuit opening relay to fuel pump.
- Checks for B + signal to circuit opening relay.
- Checks for proper MAF fuel pump switch.
Diagnostic Aids
Visual inspection of wiring and connectors should be made if an intermittent problem exists.
CODE 12 AND/OR 13 NO RPM SIGNAL (NO SIGNAL FOR 2 SECONDS) 1.6L (VIN 5) "S" CARLINE (PORT)
Circuit Description
The ECM supplies a voltage signal to the pick up coil. As the stator inside the distributor passes the pick up coil the voltage signal is pulled low. This low voltage (signal) is then used to sequence the fuel injector. If this signal is not present for 2 seconds, Code 12 and/or 13 will set.
Test Description
Numbers below refer to circled numbers on the diagnostic chart.
- Voltage is supplied by the ECM to the pick up coil.
- Determines if rpm signal is present at the ECM.
- Checks for proper resistance of the pick up coil.
- Checks for proper resistance of the signal rotor coil.
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect ECM harness connectors for backed out terminals, "NE", "GO +", "GO -", "1GT", 1GF", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
IGNITION SIGNAL CIRCUIT - (NO SIGNAL) 1.6L (VIN 5) "'S" CARLINE (PORT)
Circuit Description
The ECM sends a voltage signal to the igniter on terminal "1GF" of ECM. If this signal is not present four times during cranking, the Code 14 will set. The igniter uses this signal to pulse the injector.
Test Description
Numbers below refer to circled numbers on the diagnostic chart.
- Verifies B+ signal from ECM.
- Checks for a short to ground in BLK/YEL wire.
Diagnostic Aids
An intermittent may be caused by a poor connection rubbed through wire insulation or a wire broken inside the insulation. Inspect ECM and igniter harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness. Inspect tachometer in I/P for proper operation. If inoperative, check for poor connection, or open or ground in BLK (1GT) wire.