AB No NGS Response

NOTE: Refer to the PINPOINT TEST section of the Flow of Diagnosis before beginning this pinpoint test. Flow of Diagnosis

NORMAL OPERATION:
The anti-lock brake control module will initialize and allow diagnostics when it is supplied with greater than 8 volts at the ignition voltage input (pin 8).

FAULT DESCRIPTION:
The anti-lock brake control module will not allow diagnostics if less than 8 volts is available at pin 8. As a result, the anti-lock indicator will remain "ON" and the scan tool will display NO RESPONSE.

POSSIBLE CONTRIBUTING CONDITIONS:
- Fault in circuit 70 (O) between the anti-lock brake control module and the data link connector (DLC).
- Low battery voltage (less than 8 volts).
- Blown 15A HEGO fuse.
- Poor anti-lock brake control module ground.
- Defective circuit in the anti-lock brake control.

AB1- Verify Connections
- Turn ignition switch to "OFF".
- Verify that the scan tool is properly connected to the DLC and to a known good power source. Refer to scan tool manufacturers instructions.
- Retrieve DTC's using the scan tool.
- Is a valid DTC or System Pass obtained?
YES - Return to System Pre-check.
NO - Go to AB2.

AB2- Check Control Module Power Supply
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Turn ignition switch to "RUN".
- Measure the voltage between breakout box pin 8 and pin 1.
- Turn ignition switch to "OFF".
- Was the voltage greater than 8 volts?
YES - Go to AB4.
NO - Go to AB3.

AB3- Check Circuit
- Remove 15A HEGO fuse.
- Disconnect connector from anti-lock brake relay.

Circuit 710 Test. HEGO Fuse.:

- Measure the resistance between breakout box pin 8 and the top terminal of the 15A HEGO fuse holder.
- Measure the resistance between breakout box pin 8 and pin 1.
- Is the resistance less than 5 ohms between breakout box pin 8 and the top terminal of the 15A HEGO fuse holder, and greater than 10,000 ohms between breakout box pin 8 and pin 1?
YES - Reinstall the fuse and the anti-lock relay and go to AB4.
NO - Repair circuit 710 (W) and return to the System Precheck.

AB4- Check Vehicle Power Supply
- Measure battery voltage.
- Is the voltage greater than 8 volts?
YES - Go to AB5.
NO - Check the charging system and battery. Refer To: Starting and Charging.

AB5- Check Communication Link
- Check DLC circuits. Refer To Powertrain Management.
- Are the DLC circuits OK?
YES - Replace the anti-lock brake control module and return to System Pre-check.
NO - Repair defective circuits and return to System Pre-check.