Specifications
99
Troubleshooting and Communication Problems Common Problems
Common Problems
Some common problems that may prevent communication between the Scanner and ECU are
listed below:
1. Vehicle identification—Check the vehicle identification entered from the VIN plate. If in doubt,
reenter the identification.
2. Scanner connections—See “Check Scanner Connection and Operation” on page 99 for
information on Scanner cables and connections.
3. Ignition off when connecting Scanner—Be sure the ignition is off when connecting and
disconnecting the Scanner. If the ignition is on when the Scanner is connected or
disconnected, Scanner memory may be disrupted. Erase and reenter the vehicle
identification if this occurs.
4. Loss of power to the computer—The computer receives battery voltage through one or more
fusible links in the wiring harness. Use a wiring diagram to check computer connections for
battery voltage and ground. If a fusible link is open, the computer cannot communicate with
the Scanner.
5. Loss of power to the Scanner when using the optional Power Pac kit accessory—The Power
Pac provides external battery power to the Scanner, independently of the vehicle. The Power
Pac requires periodic charging using the adapter included in the kit. A discharged Power Pac
can cause the Scanner display to flicker or extinguish without warning, terminating
communication.
Common Symptoms
If the Scanner displays the no communication message, it means that the Scanner and the
vehicle computer simply cannot communicate with each other for some reason. If the no
communication message appears, check the vehicle battery state of charge, and check the
Scanner data cable continuity as described below.
Check Scanner Connection and Operation
If the Scanner fails to light up or if the readings are unsteady, the Scanner may be at fault. If the
Scanner intermittently resets or goes blank, a wire may be opening intermittently in one of the
cables or in the adapter.
Check the following points:
• Use an ohmmeter to test the continuity of the Scanner power cable.
• Use an ohmmeter to test the continuity of the Scanner data cable. Measure continuity pin to
pin from the connectors at each end of the cable.