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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.
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HOMESERVICE MANUALSFORD1993PICKUP F250, 2D PICKUP, 5.0 N, STANDARD, M5OD-R2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 10 (ENGINE CONTROLS - SELF-DIAGNOSTICS - EEC-IV - GASOLINE)CIRCUIT TESTSHOW TO USE CIRCUIT TESTS
1993 Ford Pickup F250, 2D Pickup, 5.0 N, Standard, M5OD-R2
How To Use Circuit Tests
1993 Ford Pickup F250, 2D Pickup, 5.0 N, Standard, M5OD-R2SECTION How To Use Circuit Tests
WARNING: This page is about a different car, the 1994 Ford RV Cutaway, 1994 Ford Econoline, 1994 Ford Cutaway, and 1994 Ford Club Wagon. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
A breakout box, connected to vehicle harness at PCM, is necessary to perform most circuit tests. References to Test Pin No. found in CIRCUIT TEST steps refer to test terminals on manufacturer breakout box overlay. Circuit diagrams at beginning of each test identify circuit and wire colors.
- Ensure all non-EEC-IV related faults found while performing steps in BASIC TESTING - GASOLINE article in ENGINE PERFORMANCE section have been corrected. Follow each test step in order until fault is found. When more than one code is retrieved, start with first code displayed.
- CIRCUIT TESTS ensure electrical circuits are okay before sensors or other components are replaced. Always test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with ignition on unless otherwise specified in CIRCUIT TESTS.
- DO NOT measure voltage or resistance at PCM. DO NOT connect any test light unless specified in testing procedure. All measurements are made by probing rear of connector. Isolate both ends of a circuit and turn ignition off when checking continuity.
- Disconnect solenoids and switches from harness before measuring continuity and resistance or applying voltage. After each repair, reconnect all component connections and repeat QUICK TEST .
- An open circuit is defined as a resistance reading of greater than 5 ohms. This specification tolerance may be too high for some items in EEC-IV system. If resistance approaches 5 ohms, always clean suspect connector and coat it with protective dielectric silicone grease. A short is defined as a resistance reading of less than 10,000 ohms to ground, unless stated otherwise in CIRCUIT TEST.
NOTE:
In following tests, circuit diagrams and illustrations are courtesy of Ford Motor Co.
CIRCUIT TESTS are grouped as follows.
- A-C - No Start & Voltage Tests
- DA-DS - Input Sensor Tests
- FD-FF - Additional Input Component Tests
- G-J - Fuel Control System Tests
- KA-TG - PCM Output Tests
CIRCUIT TEST INDEX
| Circuit Test Title | Circuit Tested | |
|---|---|---|
| No-Start & Voltage Tests | ||
| AA | No Start (Distributor Ignition System) | |
| B | Vehicle Battery | |
| C | Reference Voltage | |
| Input Sensor Tests | ||
| DA | IAT/ECT Sensor | |
| DC | MAF Sensor | |
| DF | MAP/BARO Sensor | |
| DG | Knock Sensor | |
| DH | Throttle Position Sensor | |
| DJ | Engine RPM Sensor | |
| DL | DPFE Sensor & EVR Solenoid | |
| DN | EVP Sensor & EVR Solenoid | |
| DP | Vehicle Speed Sensor | |
| DQ | Throttle Position Sensor (7.3L Diesel) | |
| DR | Cylinder Identification Circuit | |
| DS | Programmable Speedometer/Odometer Module | |
| Additional Input Component Tests | ||
| FD | Brake On-Off (BOO) Switch | |
| FE | Electrical Load Inputs | |
| FF | Power Steering Pressure Switch | |
| Fuel Control System Tests | ||
| G | MAF/TPS Fuel Injector Pulse Width Test | |
| H | Fuel Control | |
| HA | Adaptive Fuel | |
| J | Fuel Pump Circuit | |
| PCM (Processor) Output Tests | ||
| KA | EVR Solenoid | |
| KB | CANP Valve | |
| KC | Secondary Air Injection Solenoid | |
| KD | Canister Purge Solenoid | |
| KE | Idle Air Control Solenoid | |
| KM | WAC & A/C Demand Switch | |
| KP | Octane Adjust | |
| M | Dynamic Response Test | |
| ML | STO/MIL | |
| NA | IDM (Distributor Ignition System) | |
| PA | Spark Timing Check (Distributor Ignition System) | |
| QA | No Codes/Codes Not Listed | |
| QB | Continuous Memory Service Code 15 Or 512 | |
| QC | Output State Check Not Functioning | |
| S | System Check | |
| TA | CPP/PNP Switch | |
| TB | 4x4 Low/Transmission Control Switch | |
| TC | Transmission Solenoids | |
| TD | Manual Lever Position Sensor | |
| TE | Transmission Oil Temperature Sensor | |
| TF | Transmission Speed Sensor | |
| TG | Electronic Transmission Continuous Memory Service Codes | |
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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.