Heated EGO Sensor - Diagnostic Procedure
Article No. 86-25-10MCU - 5.8L POLICE/CANADIAN TRAILER TOW VEHICLES - HEATED EGO DIAGNOSTIC PROCEDURE
FORD 1987 CROWN VICTORIA
LINCOLN-MERCURY 1987 GRAND MARQUIS
Schematics - Electrical:
The 1987 5.8L MCU Police and Canadian trailer tow vehicles will no longer use the standard EGO sensor. Instead, a heated EGO sensor will be used, which will operate in the same manner as the heated EGO sensors on EECIV vehicles. When diagnosing the 1987 vehicles with the heated EGO, use the following revised pinpoint Test #6.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"
Pinpoint Test
Fuel Always Lean
6
TEST STEP RESULT ACTION TO TAKE
6.0 SERVICE CODE 4-1 - FUEL ALWAYS
LEAN (CONTINUED)
^ Run engine at 2000 RPM for 60 seconds, Service Code 4-1 Continue to Pinpoint
to ensure that the EGO sensor is at still present. Test 6.15
an operating temperature.
^ Rerun Engine Running Self-Test. No service code SERVICE the next
4-1 present. code recorded
from this self-test.
Fuel Always Lean
Pinpoint Test
6
TEST STEP RESULT ACTION TO TAKE
6.15 CHECK HEATER ELEMENT
RESISTANCE ON HEATED EGO
^ Key Off, Engine Off. Yes GO to 6.16
^ DVOM on 200 ohm scale.
^ HEGO disconnected. No REPLACE HEGO
sensor.
^ Measure resistance between run
circuit and ground at HEGO sensor.
^ Hot to warm resistance specification
is 5 to 20 ohms.
NOTE: At room temperature, resistance
specification is 3 to 6 ohms.
^ Is resistance within specification?
6.16 CHECK FOR POWER AT HEGO
HARNESS CONNECTOR
^ Key On, Engine Off. Yes HEGO system OK.
RECONNECT HEGO
^ DVOM on 20V scale. and GO to 6.14
^ Connect positive lead to run circuit
and negative lead to ground at HEGO
vehicle harness connector. No GO to 6.17
^ Is voltage reading 10.5 volts or
greater?
6.17 CHECK CONTINUITY OF GROUND TO
HEGO CONNECTOR
^ Key Off, wait 10 seconds. Yes SERVICE open in
run circuit.
^ DVOM on 200 ohm scale.
^ Measure resistance of ground circuit
from HEGO vehicle harness connector to No SERVICE open in
battery ground. ground circuit.
^ Is resistance reading less than 5.0 ohms?