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Home >> Ford >> 1990 >> Bronco II 4WD, Standard, M5OD-R1 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Quick Test >> Step 9.0 Diagnosis By Symptom
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Step 9.0 Diagnosis By Symptom

NOTE: Verify that pass code 11 was received for the On-Demand, Continuous Memory, and Engine Running self-tests before continuing.

Use the chart to locate the proper pinpoint test for the applicable engine & symptom. All tests are in the format "Test/Step". For example, if you see "S1", proceed to pinpoint test S (TEST S - SYSTEM CHECK) and start at step #1. Be sure to read the Introduction proceeding step #1 for important supplementary information and resources.

The chart is hyperlinked for your convenience. Each link jumps to the start of the test (introduction area) proceeding step #1, not to the specified step number itself.

Since just one hyperlink can exist on a line, only the left-most pinpoint test identifier is linked. If another engine uses the same test but is not linked, use the same left-most hyperlink.

After service, rerun the Quick Test to ensure that service was effective. If all phases of the Quick Test including this DIAGNOSIS BY SYMPTOM section result in a pass, it is likely that the problem is non-EEC-IV related and will be found elsewhere.

SYMPTOM-TO-TEST CHART: TRUCK (1)

Symptom 2.3LVIN [A] 2.9LVIN [T] 3.0LVIN [U] 4.0LVIN [X] 4.9LVIN [Y] 5.0LVIN [N] 5.8LVIN [H] 7.3LVIN [M] 7.5LVIN [G]
Runs Rough Or Misses -Surges -Lack Of Power -Rough Idle -Erratic RPM S2 S2 S2 S2 (2) S2 S2 (2) S2 -- S2
Engine Stalls -Stalls In Self-Test (KOEO/KOER) S1 S1 S1 S1 S1 S1 S1 -- S1
Stalls During Parking Maneuvers FF3 FF3 FF3 -- FF3 FF3 -- -- --
A/C Compressor Runs Continuously KM35 -- -- -- FA18 -- -- -- --
Surges with A/C On At Idle KM30 -- -- -- -- -- -- -- --
A/C Does Not Cut Off Under WOT Conditions KM15 KM15 KM15 -- -- -- -- -- --
A/C Not Functioning KM1 KM1 KM1 KM1 FA17 FA17 FA17 FA17 FA17
Low Idle With A/C On FA11 FA11 FA11 FA11 FA11 FA11 FA11 -- FA11
"CHECK ENGINE" Or "SERVICE ENGINE SOON" Light Always On ML1 ML1 ML1 ML1 ML1 ML1 ML1 -- ML1
"CHECK ENGINE" Or "SERVICE ENGINE SOON" Light Never On ML5 ML5 ML5 ML5 ML5 ML5 ML5 -- ML5
"CHECK ENGINE" Or "SERVICE ENGINE SOON" Light On Intermittantly ML10 ML10 ML10 ML10 ML10 ML10 ML10 -- ML10
"CHECK ENGINE" Or "SERVICE ENGINE SOON" Light Flashing With Erratic Idle ML15 ML15 ML15 ML15 ML15 ML15 ML15 -- ML15
Stumble After Hot Restart H20 H20 H20 H20 H20 H20 H20 -- H20
Fuel Pump Runs With Engine Off J22 -- -- -- -- -- -- -- --
Gasoline Fumes Under Hood -- -- KD1 KD1 KD1 -- KD1 -- KD1
Exhaust Odor -Black Smoke H29 H29 H29 H29 H29 H29 H29 -- H29
Spark Knock KP1 (3) -- -- -- DG1 (3) DG1 (3) -- -- --
Poor Idle Quality -Rolling Idle -Shifts Harshly -Poor Fuel Economy -- -- DP1 -- -- -- -- DJ1 --
High Idle -A/C Not Functioning -- -- -- -- FA15 FA15 -- -- FA15
Overdrive Cancel Indicator (OCI) Light Always Off (E4OD Only) -- -- -- -- TC13 (4) TC13 TC13 TC13 TC13
Hard To Start (Cold) N25 -- -- -- -- -- -- -- --
Tachometer Inoperative -- -- -- -- -- -- -- DJ1 --
4x4 Low Indicator Light Always Off (Or Always On With Sluggish Shift) E4OD Only -- -- -- -- TC11 TC11 (4) TC11 TC11 TC11
Tachometer Indicates Low Vehicle RPM -- -- -- -- -- -- -- DJ1 --
(1) "--" means test not applicable for this engine.
(2) Verify that MAF sensor is properly connected.
(3) Consider the EGR system, too. See EXHAUST GAS RECIRCULATION SYSTEMS in SYSTEM/COMPONENT TESTS article.
(4) This 5.0L information has been updated to reflect FordTSB 89-25A-14.