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HOMESERVICE MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 3 (ENGINE CONTROLS - TESTS W/CODES - EEC)CIRCUIT TESTSTEST EQUIPMENT
1991 Mercury Tracer Base, 4D Sedan, Automatic

Test Equipment

1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Test Equipment
WARNING: This page is about a different car, the 1992 Mercury Tracer, 1992 Ford Probe, and 1992 Ford Escort. However, it is still accessible from the selected car via links, so may be relevant.

The following equipment is recommended for diagnosing and testing EEC system. DO NOT attempt to test this system without proper equipment. Damage to vehicle components may result if improper equipment is used.

  • The Self-Test Automatic Read-Out (SUPER STAR II) diagnostic tester is recommended but not required. It is specially built for EEC systems and is used to display the 2-digit (numeric) codes programmed into control module. Aftermarket Scan tools are also available.
  • Analog Volt-Ohmmeter (VOM) with 0-20V DC range can be used, as an alternative to the diagnostic tester, to read codes.
  • Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance
  • A breakout box is required to perform certain tests on system. The test pin No. mentioned in CIRCUIT TESTS refers to test pin No. on breakout box. Once the breakout box has been installed during a test sequence, it may stay connected for the remainder of that test, unless stated otherwise. Aftermarket breakout boxes are also available.
  • Vacuum gauge with 0-30 in. Hg range and resolution (units on scale) of 1 in. Hg
  • Tachometer with 0-6000 RPM range, +/- 40 RPM accuracy, and a resolution of 20 RPM
  • Vacuum pump with 0-30 in. Hg range
  • Timing light
  • Spark Tester (D81P-6666-A or ST-125) is required. A modified side electrode spark plug IS NOT sufficient for these testing procedures.
  • Fuel Injection Pressure Gauge (T80L-9974-A)
  • 12-volt test light (non-powered type)
  • Jumper wire about 15" long
NOTE: The following circuit tests and illustrations are provided courtesy of Ford Motor Co. Complete EEC system wiring diagrams may be found in the WIRING DIAGRAMS Section.
RENDER: 1.0x

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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.