Symptoms. Cadillac Concours 1997

For 1990-2009 cars

### Important Preliminary Checks Before Starting

Before using this section, perform the Powertrain On-Board Diagnostic (OBD) System Check and verify all of the following items:

• | The PCM and MIL (Service Engine Soon) are operating correctly.

• | There are no DTC(s) stored.

• | Ensure that the engine coolant temperature is not above 130°C (266°F). This condition will cause the PCM to operate in Engine Metal Overtemp. While in Engine Metal Overtemp, the PCM will turn fuel off to four cylinders at a time to keep engine temperatures from reaching damaging levels. Engine Metal Overtemp will be perceived as a lack of power, miss, or rough idle. If the vehicle is operating in Engine Metal Overtemp, refer to Cooling and Radiator for diagnosis.

• | Scan tool data is within normal operating range, Refer to Typical Scan Data Values .

- | An example of incorrect scan data would be an indication of the extended travel brake switch always applied. With this condition the PCM may operate the engine in a torque reduction mode at higher throttle angles. The torque reduction mode may cause a driveability concern. This condition may not set a DTC.

• | Verify the customer complaint and locate the correct symptom in the table of contents. Perform the procedure included in the symptom chart.

### Visual/Physical Check

Several of the symptom procedures call for a careful Visual/Physical. It can lead to correcting a problem without further checks and can save valuable time. This check should include the following items:

• | PCM grounds for being clean, tight, and in their proper location.

• | Vacuum hoses for splits, kinks, and proper connections, as shown on Vehicle Emission Control Information label. Check thoroughly for any type of leak or restriction.

• | Air intake ducts for collapsed or damaged areas.

• | Air leaks at throttle body mounting area, Mass Air Flow (MAF) sensor and intake manifold sealing surfaces.

• | Ignition wires for cracking, hardness, proper routing and carbon tracking.

• | Wiring for proper connections, pinches and cuts.

### Intermittents

A problem may or may not turn ON the Malfunction Indicator Lamp (MIL) or store a DTC. DO NOT use the Diagnostic Trouble Code (DTC) charts for intermittent problems. The fault must be present to locate the problem.

Most intermittent problems are caused by faulty electrical connections or wiring. Perform a careful visual/physical check for the following conditions:

• | Poor mating of the connector halves or a terminal not fully seated in the connector (backed out).

• | Improperly formed or damaged terminal.

• | All connector terminals in the problem circuit should be carefully checked for proper contact tension.

• | Poor terminal to wire connection. This requires removing the terminal from the connector body to check.

Road test the vehicle with a J 39200 Digital Multimeter connected to a suspected circuit. An abnormal voltage when malfunction occurs is a good indication that there is a fault in the circuit being monitored.

Use a scan tool to help detect intermittent conditions. The scan tool has several features that can be used to locate an intermittent condition. Use the following features to find intermittent faults:

• | The Snapshot feature can be triggered to capture and store engine parameters within the scan tool when the malfunction occurs. This stored information then can be reviewed by the service technician to see what caused the malfunction.

• | Using a Scan Tools Freeze Frame data or Failure Records data can also aid in locating an intermittent condition. Review and record the information in the freeze frame or failure record associated with the intermittent DTC being diagnosed. The vehicle can be driven within the conditions that were present when the DTC originally set

Loss of diagnostic code memory. To check, disconnect the MAP sensor and idle engine until the MIL (Service Engine Soon) comes ON. DTC P0107 should be stored and kept in memory when ignition is turned OFF. If not the PCM is faulty. When this test is completed, make sure that you clear the DTC P0107 from memory.

An intermittent MIL (Service Engine Soon) with no stored DTC may be caused by the following:

• | Ignition coil shorted to ground and arcing at ignition wires or plugs.

• | MIL (Service Engine Soon) wire to PCM shorted to ground.

• | Poor PCM grounds, refer to PCM wiring diagrams.

Check for improper installation of electrical options such as lights, cellular phones etc. Route Ignition Control (IC) Module wiring away from secondary ignition wires and ignition coils .Check all wires from the PCM to the ignition control module for poor connections.

Check for open diode across A/C compressor clutch and check for other open diodes, refer to wiring diagrams in ELECTRICAL DIAGNOSIS.

The following Symptom tables are located in this section:

• | Hard Start

• | Surges/Chuggles

• | Lack of Power, Sluggishness, or Sponginess

• | Detonation/Spark Knock

• | Rough, Unstable, or Incorrect Idle and Stalling

• | Poor Fuel Economy

• | Excessive Exhaust Emissions or Odors

• | Dieseling, Run-On

• | Backfire

• | Cuts Out, Misses

• | Hesitation, Sag, Stumble

• | Restricted Exhaust System Check