Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1986 Merkur XR4Ti AutomaticFACTORY OEM SERVICE PROCEDURE
EEC IV System
- Description
- Operation
- Notes
- Inputs
- A/C Compressor Clutch Signal
- Air Charge Temperature (ACT) Sensor
- Barometric Pressure Sensor (BPS)
- Detonation (Knock) Sensor
- EEC Power Relay
- EGR Valve Position Sensor (EVP)
- Engine Coolant Temperature (ECT) Sensor
- Idle Tracking Switch (ITS)
- Neutral Drive Switch (NDS) & Neutral Gear Switch (NGS)
- Oxygen Sensor (EGO)
- Profile Ignition Pick-Up (PIP)
- Self-Test Input (STI)
- Throttle Position Sensor (TPS)
- Vane Airflow Meter (VAF)
- Outputs
- Diagnosis & Testing
- Quick Test
- Symptom Testing
- Circuit Tests
- How To Use Circuit Tests
- Circuit Test A - No Start
- Circuit Test B - Vehicle Battery
- Circuit Test C - Reference Voltage
- Circuit Test D - Vane Air Temperature (Vat) Sensor
- Circuit Test G - Engine Coolant Temperature (ECT) Sensor
- Circuit Test H - Manifold Absolute Pressure (Map)/Barometric Pressure (BP) Sensor
- Circuit Test I - Knock (Detonation) Sensor
- Circuit Test J - Throttle Position Sensor (TPS)
- Circuit Test K - Vane Airflow (VAF) Sensor
- Circuit Test M - Neutral Drive Switch-A/C Input
- Circuit Test Q - Fuel Control
- Circuit Test V - Fuel Pump Circuit (Inertia Switch)
- Circuit Test W - EGR On/Off Check
- Circuit Test Y - Canister Purge (CANP) Check
- Circuit Test Z - Idle Speed Control (By-Pass Air)
- Circuit Test Ff - Shift Indicator Light (SIL)
- Circuit Test HH - Turbo Boost
- Circuit Test KK - Dynamic Response Test
- Circuit Test Ll - Ignition Diagnostic Monitor (IDM)
- Circuit Test Mm - Spark Timing Check
- Circuit Test NN - No Codes/Codes Not Listed
- Circuit Test Oo - Erratic Ignition
- Circuit Test SS - System Check
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.