Jeep Wagoneer/Commando/Cherokee 1984-1998

Diagnosis and Testing


See Figures 1, 2 and 3

The CEC system should be considered as a possible source of trouble only after normal tests, that would apply to a vehicle without the system, have been performed.

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Fig. Fig. 1: 2.5L CEC diagnostic connector

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Fig. Fig. 2: 2.5L CEC system wiring diagram

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Fig. Fig. 3: 6-cylinder diagnostic connector

The CEC Fuel Feedback System incorporates a diagnostic connector to provide a means for systematic evaluation of each component that could cause an operational failure. Electronic Fuel Feedback testers, ET-501-82 and ET-501-84 or equivalent, are available to aid in the system diagnosis. When a tester is not available, other test equipment can be substituted.

The equipment required to perform the checks and tests includes a tachometer, a hand vacuum pump and a digital volt-ohmmeter (DVOM) with a minimum ohms per volt of 10 megaohms.

The use of a voltmeter with less than 10 megaohms per volt input impedance can destroy the oxygen sensor. Since it is necessary to look inside the carburetor with the engine running, observe the following precautions.

Before performing the Diagnostic Tests, other engine associated systems that can affect air/fuel mixture, combustion efficiency or exhaust gas composition should be tested for faults. These systems include:

  1. Basic carburetor adjustments.
  3. Mechanical engine operation (spark plugs, valves, rings, etc.).
  5. Ignition system components and operation.
  7. Gaskets (intake manifold, carburetor or base plate); loose vacuum hoses or fittings, or loose electrical connections.