Your Vehicle: 2001 Ford Escort ZX2 L4-2.0L DOHC VIN 3
 
Vehicle » Powertrain Management » Computers and Control Systems » Testing and Inspection » Reading and Clearing Diagnostic Trouble Codes » Reading Diagnostic Trouble Codes » Performance Diagnostic Overview (Quick Test)  
 
 
  Performance Diagnostic Overview (Quick Test)  
 

Quick Test

Quick Test Quick Test is divided into three specialized tests:

1 Key On Engine Off (KOEO) On-Demand Self-Test
2 Key On Engine Running (KOER) On-Demand Self-Test
3 Continuous Memory Self-Test

Quick Test checks the integrity and function of the Electronic EC System and outputs the test results when requested by a scan tool. Quick Test also provides a quick end check of the powertrain control system and is usually performed at the start of each diagnostic procedure with all accessories off. Quick Test is also performed at the end of most pinpoint tests for verification of repair and to make sure no other faults were incurred while repairing a previous fault. A system pass will be displayed when no DTCs are output and a scan tool communication error does not exist. System pass means that hardware monitored by the PCM is functioning within normal operating limits. Only a system pass, DTC or an incomplete OBDII drive cycle (P1000) will be displayed.

Key On Engine Off (KOEO) On-Demand Self-Test

Key On Engine Off (KOEO) On-Demand Self-Test is a functional test of the powertrain control module performed on demand with the key on and the engine off. This test will perform checks on certain sensor and actuator circuits. A fault must be present at the time of testing for the KOEO Self-Test to detect the fault. When a fault is detected, a Diagnostic Trouble Code (DTC) will be output on the data link at the end of the test when requested by a scan tool.

Key On Engine Running (KOER) On-Demand Self-Test

Key On Engine Running (KOER) On-Demand Self-Test is a functional test of the powertrain control module performed on demand with the key on engine running and vehicle stopped. A check of certain inputs and outputs is made during operating conditions and at normal temperature. The brake pedal position, transmission control and power steering switch tests are part of KOER On-Demand Self-Test and MUST be performed during this operation if applicable. These are described below. A fault must be present at the time of testing KOER On-Demand Self-Test to detect the fault. When a fault is detected, a Diagnostic Trouble Code (DTC) will be output on the data link at the end of the test when requested by a scan tool.

Brake Pedal Position Test

This tests the ability of the Electronic EC system to detect a change of state in the stoplight switch. Brake pedal MUST briefly be applied and released on all vehicles equipped with Brake Pedal Position input. This is done during KOER On-Demand Self-Test.

Transmission Control Switch Test

This tests the ability of the Electronic EC system to detect a change of state in the Transmission Control Switch (TCS) . Switch MUST briefly be cycled on all vehicles equipped with TCS input. This is done during KOER On-Demand Self-Test.

Power Steering Pressure Test

This tests the ability of the Electronic EC system to detect a change in power steering system fluid pressure. The steering wheel MUST briefly be turned at least 1/4 of a revolution on vehicles equipped with a Power Steering Pressure (PSP) switch or sensor. This is done during KOER On-Demand Self-Test.

Continuous Memory Self-Test

Testing for Continuous Memory DTC's is a functional test of the powertrain control module performed under any condition (engine running or off) with the key on. Unlike the KOEO and KOER self tests, which can only be activated on demand, the Continuous Self Test is always active. A fault does not need to be present at the time of testing for Continuous DTC's and is therefore, especially valuable when diagnosing intermittent faults. This test will detect failures contributing to driveability or emission concerns. The vehicle may need to be driven or the OBDII Drive Cycle completed to allow the PCM to detect a fault. Refer to Drive Cycles for more information. See: Monitors, Trips, Drive Cycles and Readiness Codes\Standard Models (Non Bi-Fuel) (Base Gasoline)\Drive Cycles

When a fault is stored in memory, a Diagnostic Trouble Code (DTC) will be output on the data link at the end of the test when requested by a scan tool.

There are two types of Continuous DTC's. The first type is an emission related Malfunction Indicator Lamp (MIL) code which will illuminate the CHECK ENGINE or SERVICE ENGINE SOON indicator in the instrument cluster. The second is a non emission related non-MIL code which will never illuminate the cluster indicator.

For emission related MIL codes, the PCM will store the DTC in continuous memory when a fault is detected for the first time. At this point the DTC will not illuminate the MIL and is now considered a pending code. The purpose of pending codes is to assist in repair verification by reporting a pending DTC after one drive cycle. If the same fault is detected after the next ignition start-run cycle, the emission related MIL code will illuminate the MIL. The MIL will remain on even if the fault is intermittent. The MIL will be extinguished if the fault is not present through three consecutive drive cycles or a PCM reset is performed. Also, an emission related pending MIL and non emission related (non-MIL) code will be erased after approximately 40-80 vehicle warm up cycles or a PCM reset.

Any scan tool that meets OBDII requirements can access Continuous Memory to retrieve emission related MIL DTC's. However, not all scan tools access pending and non emission related (non-MIL) DTC's in the same way.

During most diagnostic procedures in this manual, it is required that all DTC's be retrieved and cleared. Consult the instruction manual from the tool manufacturer for specific instructions.