Hardware Limited Operational Strategy (HLOS)
If a number of system or sensor failures are present and PCM is not receiving enough information to operate, PCM will switch to HLOS mode. PCM will output fixed values to allow operation of vehicle. Driveability performance will be reduced.
EEC-IV DIAGNOSIS BY SYMPTOM
| Symptom | Application | Circuit Test | ||
|---|---|---|---|---|
| A/C Does Not Cut Off During WOT | Explorer | KM - Step 15) | ||
| A/C Not Functioning | Explorer | KM - Step 1) | ||
| Black Exhaust Smoke | Explorer | H - Step 1) | ||
| CHECK ENGINE Light Always On | (1) Explorer | ML - Step 1) | ||
| CHECK ENGINE Light Flashing With Erratic Idle | (1) Explorer | ML - Step 15) | ||
| CHECK ENGINE Light Never On | (1) Explorer | ML - Step 4) | ||
| CHECK ENGINE Light On Intermittently | Explorer | ML - Step 10) | ||
| Engine Hesitates After Hot Restart | (1) Explorer | H - Step 21) | ||
| Engine Hesitation | (1) Explorer | S - Step 2) | ||
| Engine Lacks Power or Loses Power | (1) Explorer | S - Step 2) | ||
| Engine Miss At Idle, Acceleration Or Cruise | (1) Explorer | S - Step 2) | ||
| Engine Runs Rough At All Times | Explorer | S - Step 2) | ||
| Engine Stalls | Explorer | S - Step 2) | ||
| Engine Stalls During Trans. Downshift | Models With A/T | TC - Step 1) | ||
| Engine Stalls During Trans. Engagement | Models With A/T | TC - Step 1) | ||
| Engine Stalls When Parking | Models With PSP Switch | FF - Step 2) | ||
| Engine Surge At Acceleration Or Cruise | (1) Explorer | S - Step 1) | ||
| Erratic RPM | (1) Explorer | S - Step 1) | ||
| Gasoline Fumes | Models With CANP | KD - Step 1) | ||
| Late Shift Into 4x4 High | Models With A/T | TB - Step 5) | ||
| Overdrive Cancel Indicator Off | Models With A/T | TB - Step 4) | ||
| 4x4 Low Light Always Off & Harsh Shift | Models With A/T | TB - Step 1) | ||
| 4x4 Low Light Always On & Shift Slipping | Models With A/T | TB - Step 1) | ||
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