Scan Tool Testing and Procedures

The "SCAN" data values, listed below, are typical for the test parameters of a "TECH-1" or equivalent "scan" tool connected to the ALDL diagnostic connector, and under the following conditions:

Engine running at idle/closed throttle.
Engine at normal operating temperature.
System operating in "closed-loop".
Accessories "OFF".
Brake NOT applied.

Many of the parameters show "data" rather than voltage or resistance values, and cannot be read using a volt/ohm meter.


PARAMETER UNITS TYPICAL VALUE

Engine Speed RPM ± 100 RPM from desired idle
Desired Idle RPM varies with temperature
Coolant Temp °C°F Varies 85-109°C (185-223°F)
Intake Air Temp °C°F Varies
MAP kPa/Volts 29 - 48 kPa/1 - 2 volts)
BARO kPa/Volts 58 - 114 kPa/2.5 - 5.5 volts depending on altitude and barometric pressure
Throttle Position Volts 0.29 - 0.98
Throttle Angle Percent (%) 0%
Oxygen Sensor Millivolts (mV) Varies (100-900)
Injector Pulse Width M/sec (milliseconds) 1 - 4 and varying
Spark Advance Degrees Advance 16° (varies)
Fuel Integrator Counts varies
Block Learn Counts 110 - 156
Open/Closed Loop Open/Closed Loop Closed Loop
Block Learn Cell Cell # 0 or 1
Knock Retard Degrees 0°
Knock Signal Yes/No No
EGR 1/EGR 2/EGR 3 On/Off Off
Idle Air Control Counts 5 - 50
Park/Neutral P-N/R-DL P-N
Vehicle Speed mph/kph 0
Shift light On/Off Off
TCC Mode On/Off Off
Batt/Ign Volts Volts 13.5-14.2
Fuel Pump Volts Volts 13.5-14.2
Crank RPM RPM Varies
Air Pump Relay On/Off Off
A/C Request Yes/No No
A/C Clutch On/Off Off
A/C Pressure PSI/Volts Varies
Fan #1, Fan #2 On/Off Off (coolant temperature below 109°C/223°F)
Power Steering Normal/High Normal
Purge Duty Cycle Percent 0%
Trans Mode Switch On/Off On
Shift Solenoid "A" On/Off Off
Shift Solenoid "B" On/Off Off
Low Range/1st Gear Yes/No No
Overdrive/4th Gear Yes/No No
Clutch Switch (manual trans) On/Off Off (On w/clutch pedal depressed)
PROM ID PROM # Internal ID Only (this is not the service part number)
Time From Start Minutes


If all values are within the specified range, Testing and Inspection