No Scan Tool Data

Diagram Chart:

CIRCUIT DESCRIPTION

IMPORTANT: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). When diagnostics call for replacement of the ECM, program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Refer to ECM / Service and Repair.

The diagnostic tables in Computer and Control Systems are designed for use with a scan tool. If the scan tool is inoperative, this condition must be corrected before beginning any other diagnostic procedures. If the scan tool being used is powered through the Data Link (DLC) connector, the B+ power is provided by DLC Pin 16. DLC Pin 4 provides the ground for the scan tool's power supply. DLC Pin 5 is an additional ground for serial data. The serial data for the powertrain diagnostics is on DLC Pin 7.

TEST DESCRIPTION

The number(s) below refer to the step number(s) on the Diagnostic Table:

2. If the ground circuit on the DLC pin 4 opens after the scan tool is up and running, the screen will go blank but the scan tool may remain on. if there is no ground at pin 4 initially, the scan tool will not power up.

9. Some of the older scan tools are powered through a separate power cord from the cigar lighter. If this type of scan tool is being used, and the tool will not power up, check for a poor connection, or a malfunctioning lighter socket. Refer to Overall Vehicle Information / Diagrams / Electrical / Cigar Lighter for circuit details.

13. If there is no communication between the ECM and the scan tool, no data will be displayed. The Serial Data is disrupted when the system voltage is below 9.0 volts or above 16.0 volts. A scan tool will not display data if the system voltage is outside of this range. If no data is displayed with the engine running, but the data is displayed with the Turn on the ignition with the engine off, high system voltage (overcharging) may be at fault. If this is the case, the scan tool should display DTC P0560 System Voltage with the ignition on and the engine off.

15. Try the scan tool on another Catera if one is available. The Catera uses International Standards Organization (ISO) serial data and communicates with the scan tool on DLC pin 7. Most of the other GM OBD II vehicles use Class 2 serial data on DLC pin 2. Therefore, testing the scan tool on a vehicle that uses a different serial data system will not verify that the tool can communicate properly on pin 7. An alternate approach is to try a different scan tool on the same vehicle, if one is available. Before trying a different scan tool, check for poor connections between the DLC and the scan tool cable. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure.

18. Before trying a different scan tool, check for poor connections between the DLC and the scan tool cable. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids Checking Terminal Contact procedure.