Scan Tool Testing and Procedures

SCAN TOOL HOOK-UP

- Connect the scan tool to the diagnostic connector located in the engine compartment. The separate red clip is connected to the positive post of the battery.
- With the scan tool properly connected, all character positions on the display should briefly illuminate, and the copyright message should appear.
NOTE: At any time after the copyright screen, the user may press the F3 key for help.
- A commonly reported problem is that the scan tool screen is blank. If the screen is blank after the scanner is attached to the vehicle, do the following:
Make sure all cable connections are properly seated and fit snugly.
Make sure the cables are in good condition (no broken or shorted wires).
Make sure the cartridge is installed properly into the scan tool.
Try the scan tool on another vehicle. If the scan tool screen is still blank, have the unit repaired. If it now performs properly, continue with next step.

Data Link Connector Identification:

Make sure all cable connectors are in good condition (no flared or pushed out terminals). If the connector is good, continue with next step.

On-Board Diagnostic Connector Identification (Wire Color May Vary By Model):

Check the BK/WT wire in the diagnostic connector for continuity to ground.

ACCESSING/DELETING FAULT CODES, RESETTING EMR LIGHT/RESETTING EMR MEMORY

CAUTION: Be sure to apply parking brake and/or block wheels before performing idle check or adjustment, or any engine running tests.

Diagnostic Connector Location:

1. Connect the scan tool to the diagnostic connector located in the engine compartment near the Single Board Engine Controller (SBEC).
2. If possible, START the engine, turn ON the air conditioning, and shift the transmission selector through all of the gears, returning to PARK (A/T) or NEUTRAL (M/T). Turn OFF the air conditioning and shut OFF the engine.
3. Turn ON the ignition switch and observe the CHECK ENGINE LAMP. It should light for approx. 2 seconds then go out.
4. Using the DRB II, go to the SELECT SYSTEM menu that looks like this:
1) ENGINE
2) TRANSMISSION
3) BODY
4) SUSPENSION
5) ABS
6) PASSIVE REST
7) THEFT ALARM

5. Select the ENGINE option. The following menu will appear:
1) WITH A/C
2) WITHOUT A/C



6. Select the appropriate option. The following menu will appear:
1) FUEL/IGNITION
2) CHARGING
3) SPEED CONTROL


7. Select the FUEL/IGNITION option. The following menu will appear:
1) SYSTEM TESTS
2) READ FAULTS
3) STATE DISPLAY
4) ACTUATOR TEST
5) ADJUSTMENTS

8. To extract fault codes, select the READ FAULTS option and all of the faults that are stored in the computers memory will be displayed. Write all of the fault codes down. Refer to FAULT MESSAGE TO DIAGNOSTIC CHART CONVERSION for a listing of fault codes and related diagnostic routines.


9. To delete existing fault codes or reset the EMR light, select the ADJUSTMENTS option. The following menu will appear:
1) ERASE FAULTS
2) RESET MEMORY
3) RESET EMR LIGHT
4) EMR MEMORY CHECK


10. Select ERASE FAULTS option to clear fault codes, or select RESET EMR LIGHT option to reset the EMR light in the instrument panel.
11. If the engine controller has been changed, the EMR memory has to be updated with the current mileage of the vehicle. This can be done by selecting RESET MEMORY in the current menu.


MONITORED CIRCUITS

The engine controller can detect certain faults in its systems, the following is a list of the types of faults the engine controller can detect.

Open or Shorted Circuit - The engine controller can determine if the input signal from the sensor is within its range and if the sensor circuit is open or shorted.
Output Device Current Flow - The engine controller can see if the output devices are hooked up. If a problem exists with an output devices' circuit, the engine controller can determine if it is open, shorted high, or shorted to ground.
Oxygen Sensor - Once the system has entered closed loop, the engine controller checks that the oxygen sensor is switching between rich and lean. Refer to Powertrain Management/Computers and Control Systems/Electronic Control Module/Description and Operation.



NON-MONITORED CIRCUITS

The following circuits, systems and conditions that cause driveability problems are not monitored by the engine controller. Fault codes may not be displayed for these areas, but problems with them may cause fault codes to be displayed for other systems. For example, a fuel injector problem will not yield a fault directly, but could cause a rich or lean fuel mixture condition. This could cause an oxygen sensor fault to be stored in the engine controller.

Cylinder Compression - The engine controller cannot detect uneven, high, or low engine cylinder compression.
Engine Controller Connector Engagement - The engine controller cannot tell if connector pins are spread or damaged, but a fault code may be set as a result of this condition.
Engine Controller System Ground - The engine controller has no way of determining a poor system ground, but a fault may be generated if a poor system ground condition exists.
Engine Timing - The engine controller cannot tell if a cam gear, crank gear, or ignition distributor is indexed incorrectly. Any of the previous problems could result in a lean or rich air/fuel mixture, causing an oxygen sensor fault to be generated.
Evaporative System - The engine controller has no way to determine if the charcoal canister or its purge hoses are plugged, restricted, or loaded with fuel.
Excessive Oil Consumption - Even though the engine controller monitors exhaust oxygen content, via the oxygen sensor, when the vehicle is in closed loop, it cannot detect excessive oil consumption.
Exhaust System - The engine controller cannot determine or detect if an exhaust system is plugged, restricted, or leaking.
Fuel Pressure - Fuel pressure is controlled by the pressure regulator, and the pressure regulator is controlled by the vacuum signal sent from the throttle body. The engine controller cannot determine if the fuel pump pressure is too low or high, if the fuel filter is clogged, if the inlet or return lines are pinched or restricted, or if the fuel pump filter is clogged or restricted. Any of the previous problems could cause a lean or rich air/fuel mixture, resulting in an oxygen sensor code being generated.
Fuel Injector Malfunctions - The engine controller cannot determine if the wrong injector has been installed, if the pintle is clogged or stuck, or if the injector tip has completely worn out. Any of the previous problems could cause a lean or rich air/fuel mixture, resulting in an oxygen sensor code being generated.
Secondary Ignition Circuit - The engine controller cannot detect fouled or worn spark plugs, inoperative ignition coil, ignition cross firing, or open spark plug cables.
Throttle Body Air Flow - The engine controller cannot detect a clogged air filter element, a restricted air cleaner inlet, a dirty throttle body or plenum, or a clogged or dirty air bypass passage. Any of the previous problems could cause a lean or rich air/fuel mixture, resulting in an oxygen sensor code being generated.
Vacuum Assist - The engine controller cannot determine if the vacuum circuits of the vacuum assisted components have leaks, restrictions, or cracked hoses. Any of the previous problems could cause a MAP sensor fault to be generated.



STATE DISPLAY TEST MODE

The switch inputs that are used by the engine controller have only two states, HI and LOW. Because of the logical process of the engine controller, it cannot determine the difference between a selected switch position and an open or shorted circuit, or a defective switch. If the change from OFF to ON or ON to OFF is displayed (scan tool) then it can be assumed that the entire switch circuit to engine controller is functional. Connect the scan tool to the vehicle and access "State Displays". Access "Inputs and Outputs" or "Sensors".

State Display Inputs and Outputs

- A/C Clutch Relay
- A/C Switch Sense
- Auto Shutdown Relay
- Brake Switch
- Check Engine Lamp
- EGR Solenoid
- EMR Lamp
- Purge Solenoid
- Radiator Fan Relay
- Speed Control ON/OFF
- Speed Control Resume
- Speed Control SET
- Speed Control Vacuum Solenoid
- Speed Control Vent Solenoid
- Z1 Voltage Sense



State Display Sensors

- Adaptive Fuel Factor
- AIS Motor Position
- Barometric Pressure
- Battery Temperature Sensor
- Battery Voltage
- Charge Temperature
- Charge Temperature Sensor
- Charging System Goal
- Coolant Temperature
- Coolant Temperature Sensor
- DIS Sensor Status
- Engine Speed
- Fault #1 Key-On Info
- Fault #2 Key-On Info
- Fault #3 Key-On Info
- Knock Sensor Signal
- Overall Knock Retard
- MAP Gauge Reading
- MAP Sensor Reading
- MAP Sensor Voltage
- Minimum Throttle
- Minimum Air Flow Idle Speed
- Module Spark Advance
- Oxygen Sensor Signal
- Oxygen Sensor State
- Speed Control Status
- Speed Control Target
- Theft Alarm Status
- Throttle Opening
- Throttle Position Sensor
- Total Spark Advance
- Vehicle Speed



CIRCUIT ACTUATION TEST MODE

The circuit actuation test mode checks for the proper operation of output circuits and devices that the engine controller cannot test. The engine controller attempts to actuate these outputs and allows an observer to verify the operation of the component. Most of the checks in this mode provide an audible or visual indication of component operation. Unless an intermittent condition exists, if a device functions properly during its test, it can be assumed that the component and its related circuit are functioning properly. To enter circuit actuation mode, access the "Actuators" screen on the scan tool.

The following can be tested in this mode:


- Air conditioning clutch relay
- All solenoids/relays
- Alternator field
- Automatic Idle Speed (AIS) motor
- Auto shutdown (ASD) relay`
- ASD fuel system test
- Fuel injector #1
- Fuel injector #2
- Fuel injector #3
- Ignition coil #1
- Ignition coil #2
- Ignition coil #3
- Purge solenoid
- Radiator Fan Relay
- Speed control servo solenoids