PCM - MIL ON Intermittently/Codes 173 and 177 Set
Article No.93-16-12
08/04/93
LAMP - "CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL) INTERMITTENTLY ON - SERVICE CODES 173 AND 177 STORED IN MEMORY - NO DRIVE CONCERNS - VEHICLES WITH 3.0L ENGINE
LIGHT TRUCK:
1992 RANGER
CALIBRATION:
2-55F-R00, 2-56F-R00, 2-56F-R10
WARNING:
THIS MODIFICATION IS AUTHORIZED ONLY FOR THE LISTED ENGINE. PERFORMING THIS MODIFICATION ON OTHER ENGINE CALIBRATIONS IS UNAUTHORIZED AND COULD CREATE LIABILITY UNDER APPLICABLE FEDERAL OR LOCAL LAWS.
ISSUE:
The "Check Engine" Malfunction Indicator Light may be activated intermittently during a steady state cruise soon after engine start up. Service codes 173 and 177 will be stored in continuous memory with no noticeable drive symptoms present. The MIL activation may be caused by the powertrain control module (PCM) calibration performing the Heated Exhaust Gas Oxygen (HEGO) Test during open loop operation with no actual fault existing.
ACTION:
Use the following service procedure to determine if a new PCM with a revised calibration is required.
1. Perform normal diagnosis to be sure that no fault is present. Refer to the 1992 Powertrain Control Emissions Diagnosis Car/Truck Service Manual for MIL light concerns.
2. Check for codes 173 or 177 in KOEO (Key ON Engine OFF) and KOER (Key ON Engine Running) Self Test modes. Service as required.
3. If these codes appear only in Continuous Memory mode, install a new PCM with a revised calibration. Refer to the following PCM Application Chart for correct parts usage.
Obtain an Authorized Modifications Decal and list the date, dealer number, and summary of alterations performed. Select a prominent place adjacent to the Vehicle Emission Control Information Decal suitable for installing the Authorized Modifications Decal. Clean the area, install the decal, and cover it with a clear plastic decal shield.
Parts Block
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS:
Eligible Under Bumper To Bumper Warranty Coverage, Emissions Warranty Coverage
OPERATION DESCRIPTION TIME
931612A Perform EEC Quick Test, 0.9 Hr.
Replace PCM, Re-run Quick Test
DEALER CODING
BASIC PART NO. CONDITION CODE
12A650 08
OASIS CODES: 206000, 690000