Diagnostic Tools
Below is an equipment list with corresponding part numbers
REQUIRED EQUIPMENT
- Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool with functionality described under Scan Tool Setup and Functionality.
- Rotunda Smoke Machine, Fuel Evaporative Emission System Tester 218-00001 (522) or equivalent.
RECOMMENDED EQUIPMENT
- Rotunda Vacuum/Pressure Tester 164-R0253 or equivalent. Range 0-101.3 kPa (0-30 in-Hg.) Resolution 3.4 kPa (1 in-Hg.)
- Rotunda Vacuum Tester 014-R1054 or equivalent. Range 0-101.3 kPa (0-30 in-Hg.)
- Rotunda 73III Automotive Meter 105-R0057 or equivalent. Input impedance 10 Megaohm minimum.
- Spark Tester D81P-6666-A (303-D037) or equivalent.
- Non-powered test lamp.
OPTIONAL EQUIPMENT
- Rotunda Fuel (Gasoline) pressure test kit 134-R0087 or equivalent. (Use tool manufacturer's instructions.)
Scan Tool Setup and Functionality
Connect the scan tool to the data link connector (DLC) for communication with the vehicle.
The DLC is located in the driver side compartment under the steering column. It is attached to the instrument panel and accessible from the driver seat.
The DLC is rectangular in design and capable of accommodating up to 16 terminals. The connector has keying features to allow easy connection.
The required scan tool functions are described below
- monitor, record, and playback of parameter identification (PIDs)
- freeze frame PID data
- diagnostic test modes; self-test, clear diagnostic trouble codes (DTCs)
- output test mode
- resetting keep alive memory (KAM)
- diagnostic monitoring test results (mode 6) for on board diagnostic (OBD) on board monitors
- on-board system readiness (OBD monitor completion status)
Some of these functions are described. Refer to the scan tool manufacturer's instruction manual for specific information on scan tool setup and operation.
Quick Test
The quick test is divided into 3 specialized tests
- Key On Engine Off (KOEO) On-Demand Self-Test
- Key On Engine Running (KOER) On-Demand Self-Test
- Continuous Memory Self-Test
The quick test checks the integrity and function of the electronic engine control (EEC) system and outputs the test results when requested by the scan tool. The quick test also provides a quick check of the powertrain control system, and is usually carried out at the start of each diagnostic procedure with all accessories off. The quick test is also carried out at the end of most pinpoint tests for verification of the repair and to make sure no other concerns are incurred while repairing a previous concern. A system pass is displayed when no diagnostic trouble codes (DTCs) are output and a scan tool communication error does not exist. System pass means that hardware monitored by the powertrain control module (PCM) is functioning within the normal operating limits. Only a system pass, a DTC, or an incomplete on board diagnostic (OBD) drive cycle (P1000) is displayed.
For applications that use a stand-alone transmission control module (TCM) the PCM does not output TCM DTCs. For TCM self-test and diagnostics, refer to the appropriate AUTOMATIC TRANSMISSION/TRANSAXLE article.
Key On Engine Off (KOEO) On-Demand Self-Test
The KOEO on-demand self-test is a functional test of the PCM carried out on-demand with the key on and the engine off. This test carries out checks on certain sensor and actuator circuits. A concern must be present at the time of testing for the KOEO self-test to detect the concern. When a concern is detected, a DTC is output on the data link at the end of the test as requested by the scan tool.
Key On Engine Running (KOER) On-Demand Self-Test
The KOER on-demand self-test is a functional test of the PCM carried out on-demand with the key on, the engine running and the vehicle stopped. A check of certain inputs and outputs is made during operating conditions and at a normal operating temperature. The brake pedal position, transmission control, and the power steering tests are part of the KOER on-demand self-test and must be carried out during this operation if applicable. These are described below. A concern must be present at the time of testing for the KOER on-demand self-test to detect the concern. When a concern is detected, a DTC is output on the data link at the end of the test as requested by the scan tool.
Brake Pedal Position (BPP) Test
The BPP test checks the ability of the EEC system to detect a change of state in the BPP switch. The brake pedal is briefly applied and released on all vehicles equipped with a BPP input. This is done during a KOER on-demand self-test.
Power Steering Pressure (PSP) Test
The PSP test checks the ability of the EEC system to detect a change in the power steering system fluid pressure. The steering wheel is briefly turned at least 1/4 of a revolution on vehicles equipped with a PSP switch or sensor. This is done during a KOER on-demand self-test.
Transmission Control Switch (TCS) Test
The TCS test checks the ability of the EEC system to detect a change of state in the TCS. The switch is briefly cycled on all vehicles equipped with a TCS input. This is done during a KOER on-demand self-test.
Continuous Memory Self-Test
The continuous memory self-test is a functional test of the PCM carried out 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 concern does not need to be present when accessing continuous memory self-test DTCs, making the test valuable when diagnosing intermittent concerns. The vehicle may need to be driven or the on board diagnostic (OBD) drive cycle completed to allow the PCM to detect a concern. Refer to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE for more information. When a concern is stored in memory, a DTC is output on the data link when requested by the scan tool.
There are two types of continuous DTCs. The first type is an emission-related code which illuminates the malfunction indicator lamp (MIL) in the instrument cluster. The second is a non-emission related, non-MIL code which does not illuminate the cluster indicator.
For emission-related MIL codes, the PCM stores the DTC in continuous memory when a concern is detected for the first time. At this point the DTC does 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 concern is detected after the next ignition start-run cycle, the emission-related MIL code illuminates the MIL. The MIL remains on even if the concern is intermittent. The MIL is extinguished if the concern is not present through 3 consecutive drive cycles or if the concern is fixed and the DTCs are cleared. Also, an emission-related pending MIL and any non-emission related, non-MIL DTCs are erased after approximately 40 vehicle warm-up cycles or if the DTCs are cleared.
Any scan tool that meets OBD requirements can access the continuous memory to retrieve emission-related MIL DTCs. However, not all scan tools access pending and non-emission related, non-MIL DTCs in the same way.
During most diagnostic procedures, it is required that all DTCs be retrieved and cleared. Consult the instruction manual from the tool manufacturer for specific instructions.
Diagnostic Monitoring Test Results - Mode 6
Mode 6 allows access to the results of on board diagnostic (OBD) monitor diagnostic test results. The test values are stored at the time of the particular monitor completion. Refer to mode 6 on the scan tool for test information.
Intermittent Diagnostic Techniques
Intermittent diagnostic techniques help find and isolate the root cause of intermittent concerns associated with the electronic engine control (EEC) system. The information is organized to help find the concern and carry out the repair. The process of finding and isolating an intermittent concern starts with recreating a fault symptom, accumulating powertrain control module (PCM) data, and comparing that data to typical values, then analyzing the results. Refer to the scan tool manufacturer's instruction manual for the functions described below.
Before proceeding, be sure that
- Customary mechanical system tests and inspections do not reveal a concern. NOTE: Mechanical component conditions can make a PCM system react abnormally.
- Technical Service Bulletins (TSBs), if available, are reviewed.
- Quick Test and associated diagnostic subroutines have been completed without finding a concern, and the symptom is still present.
Adaptive Fuel DTC Diagnostic Techniques
The Adaptive Fuel Diagnostic Trouble Codes (DTC) Diagnostic Techniques help isolate the root cause of the adaptive fuel concern. Before proceeding, attempt to verify if any driveability concerns are present. These diagnostic aids are meant as a supplement to the pinpoint test steps. For a description of fuel trim, refer to POWERTRAIN CONTROL SOFTWARE , Fuel Trim.
DTCs P0171/P0174 System Too Lean Diagnostic Aids
Note. If the system is lean at certain conditions, then the LONGFT PID would be a positive value at those conditions, indicating that increased fuel is needed.
The ability to identify the type of lean condition causing the concern is crucial to a correct diagnosis.
DTCs P0172/P0175 System Too Rich Diagnostic Aids
Note. If the system is rich at certain conditions, then the LONGFT PID would be a negative value at that airflow, indicating that decreased fuel is needed.
System rich concerns are caused by fuel system concerns, although the MAF sensor and base engine (for example, engine oil contaminated with fuel) should also be checked.