DR21 - Road Test

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.

NOTE: 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 test is not performed, return to Diagnostic Routines for other possible causes.

Prepare Vehicle For a Road Test

- Breakout box installed, PCM connected.

- Install fuel pressure gauge and MAP/BARO tester (optional).

- Other materials needed: DVOM, pencil, paper, appropriate schematic/pin usage sheet.

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 Normal Scan Data Values that most resembles the driveability or 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 circuits and the CID signal(s) are the main circuits 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 or Scan Tool, 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).

- After starting the engine for the road test, enter Engine Running Continuous Monitor Diagnostic Test Mode (DTM). Continuous Monitor Diagnostic Test Mode (Wiggle Test)

- Drive the vehicle to create the conditions in which symptom occurs. If the Customer information Worksheet has been completed, this information may help in creating the symptom.

- When the symptom occurs, the passenger should observe changes in listed Electronic Engine Controls (EEC) signals. information about the symptom, operating condition, value of the EEC signal or other notes should be recorded.

- If the symptom cannot be duplicated verify that the EEC 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, for example, a Continuous Memory Diagnostic Trouble Code 214 is set again and the CID signal stayed within specification, the PCM would be suspect. If the signal went out of specification, the harness or sensor would be suspect).

- If no problem is identified, return to Diagnostic Routines to continue with diagnostic procedures.