PCM - MIL ON/Codes 173 And/Or 177 Set

91ford20

Article No.
91-13-5


LAMP - MALFUNCTION INDICATOR LIGHT (MIL) - MISTAKENLY DISPLAYS CONTINUOUS MEMORY CODES 173/177


FORD: 1991 TAURUS, THUNDERBIRD

LINCOLN-MERCURY: 1991 CONTINENTAL, COUGAR, SABLE


CALIBRATION: 1-15A-R00, 1-16A-R00, 1-16F-R05,
1-16T-R05, 1-16B-R05, 1-16C-R00,
1-16Q-R00, 1-16D-R00, 1-16R-R00

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 Malfunction Indicator Light (MIL) may mistakenly come on with continuous memory codes 173/177 being set after extended driving or idling in very hot (+95~ F) ambient temperatures. This is caused by the canister purge strategy with no actual fault existing. No drive symptoms will be present and after continued driving, the MIL will go out.

ACTION: Install a new EEC-IV processor with revised operating strategy. Refer to the following procedure for service details.


1. Check to be sure that the engine calibration is listed above.

2. Confirm that the KEY ON ENGINE OFF and ENGINE RUNNING SELF-TEST result in pass codes (111).

3. Perform normal diagnosis to be sure that no fault is present. Refer to the 1991 Engine/Emissions Diagnosis Shop Manual, Part 1, for diagnostic routines.

4. If no concern is found, install a new ECC-IV processor with a revised operating strategy. Refer to the following EEC-IV Processor 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.


EEC-IV PROCESSOR APPLICATION CHART

EXISTING EEC-IV PROCESSOR NEW
CALIBRATION PART NUMBER CALIBRATION

1-15A-R00 F1WY-12A650-AC 1-15A-R12
1-16A-R00 F1WY-12A650-BC 1-16A-R12
1-16B-R06 F1DZ-12A650-GD 1-16B-R10
1-16C-R00 F1DZ-12A650-HC 1-16C-R10
1-16D-R00 F10Y-12A650-AB 1-16D-R10
1-16F-R05 F1MY-12A650-AC 1-16F-R10
1-16Q-R00 F1DZ-12A650-HC 1-16C-R10
1-16R-R00 F10Y-12A650-BB 1-16R-R10
1-16F-R05 F1MY-12A650-BC 1-16T-R10

(*) - Requires HEGO (F1SZ-9F472-A)


PART NUMBER PART NAME CLASS

F1WY-12A650-AC EEC-IV Processor B
F1WY-12A650-BC EEC-IV Processor B
F1DZ-12A650-GD ECC-IV Processor B
F1DZ-12A650-HC EEC-IV Processor B
F10Y-12A650-AB EEC-IV Processor B
F1MY-12A650-AC EEC-IV Processor B
F10Y-12A650-BB EEC-IV Processor W
F1MY-12A650-BC EEC-IV Processor W
F1SZ-9F472-A HEGO B


OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: Eligible Under Basic Warranty
Coverage, Emissions
Warranty Coverage
OPERATION DESCRIPTION TIME
911305A Perform EEC IV Diagnosis, 1.1 Hr.
Replace EEC IV Processor
And Install Decal - Taurus,
Sable, Continental
911305B Perform EEC IV Diagnosis, 1.0 Hr.
Replace EEC IV Processor
And Install Decal -
Thunderbird, Cougar
DEALER CODING
BASIC PART NO. CONDITION CODE
12A650 09
OASIS CODES: 204000, 206000