TD22 - Road Test
NOTE: The purpose of the road test is to identify an area of concern by monitoring certain controlled parameters while trying to recreate a driveability or MIL symptom.
REMEMBER: A basic working knowledge of the EEC-IV system is critical to effectively analyze road test data.
WARNING: This road test is a suggested but optional procedure. All applicable safety procedures and traffic laws must be followed. In order for a road test to be performed, it is required that another person accompany the driver. The accompanying person can make measurements, observe changes and record notes. If for some reason this testis not performed, return to diagnostic routines for other possible causes. Symptom Related Diagnostic Procedures
Prepare Vehicle For a Road Test
- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box/4EAT tester and connect PCM to breakout box/4EAT tester.
- Other materials needed: Digital Volt/Ohm Meter (DVOM), pencil, paper, appropriate schematic/pin usage sheet.
- Optional equipment:
- Fuel pressure gauge, manifold vacuum gauge, Manifold Absolute Pressure (MAP) / Barometric Pressure (BARO) tester.
Preliminary Power/Ground Checks
- With the key "ON" and a DVOM referenced to the battery negative post, check the following signals for correct values:
POWERS:
KAPWR >10.5V (Pin 1)
VPWR >10.5V (Pins 37/57)
VREF 5 (+/-) 1V (Pin 26)
GROUNDS: (all = 0 (+/-) 0.5V)
PWR GND (Pins 40/60)
SIG RTN (Pin 46)
IGN GND (Pin 16)
OPTIONAL GROUNDS:
HO2S GND (Pin 49)
CSE GND (Pin 20)
MAF RTN (Pin 9 or 15)
Obtaining Other Information and Materials Before the Road Test
- Refer to the Transmission Range Switch Voltage at EEC-IV breakout box chart.
These are the main signals that will be monitored. The Park Neutral Position (PNP) input (Pin 30) should also be monitored (with the PNP switch referenced to GND, the voltage should be about zero volts in Park or Neutral and greater than 3.0 volts in all other gearshift positions).
- Refer to the Symptom Charts in Diagnosis by Symptom (Diagnostic Routines) that most resemble the driveability or Malfunction Indicator Light (MIL) symptom. Before the road test, perform the Visual/Mechanical Checks that are listed. Next, list the EEC-IV sensors and actuators in the order given. These are the main signals that will be monitored.
- Refer to the proper Diagnostic Reference Value Sheet in Normal Scan Data Values. Although these charts were designed for use with the EEC-IV Monitor Box, most of the values can be read using the breakout box and a DVOM (with the DVOM referenced to ground, all values in DCV units can be used; other values may also be helpful, ex., MAP Hz using the MAP/BARO tester). Also refer to Graphs and Charts.
- After starting the engine for the road test, enter Engine Running Continuous Monitor Diagnostic Test Mode. Output State Diagnostic Test Mode
- Drive the vehicle to create the conditions in which the symptom will occur. If the Customer Information Worksheet from Diagnostic Routines has been completed, this information may help in recreating the symptom.
- When the symptom occurs, the passenger should observe changes in listed EEC-IV signals. Information about the symptom, operating condition, value of the EEC-IV signal or other notes should be recorded.
- If the symptom cannot be duplicated, verify that the EEC-IV values are in the expected range.
Analyzing the Data
- Once the road test is completed, the results should be analyzed to locate and service the fault which caused the symptom.
- If no problem is identified, return to Diagnostic Routines for other possible causes of the symptom. Symptom Related Diagnostic Procedures