To test a P0688 OBD code, start by checking the vehicle’s battery and ensuring it has a proper charge, as low voltage can trigger this code. Next, inspect the engine control module (ECM) and its connectors for any signs of damage or corrosion. Use a multimeter to test the power and ground circuits to the ECM, ensuring they are functioning correctly. If these checks don't reveal issues, consider testing the ECM itself, as it may be malfunctioning.
ECM/PCM Power Relay Sense Circuit /Open
What does obd code P0740 mean
I think you are referring to the Universal OBD (or OBD2) test port. This is the plug under the dash that you plug the OBD code tester into. It may also be referred to as the 16-Pin Data Link Connector (DLC).
plug a obd 2 code reader into your car and activate it.
Engine code P0688 indicates a problem with the engine control module (ECM) power relay circuit. To fix it, first, check the ECM power relay and its associated fuses for damage or failure. Inspect wiring and connectors for corrosion or shorts, and repair or replace any faulty components. If everything appears intact, consider testing or replacing the ECM itself, as it may be malfunctioning.
The EEC TEST connection is in your engine compartment by the power distribution box ( OBD I / EEC IV )
OBD I, but for the most part, you can use OBD II
OBD code P0304 is Cylinder Four Misfire.
Obd-on board diagnostic. The port is the plug the scan tool or code reader connects to.
Somewhere in the engine compartment ( battery side ) you will find an EEC TEST connection for your OBD I / EEC - IV system
J1850 is not a trouble code. It is a protocol that the OBD-II system uses. Trouble codes will be represented by a P before the numbers
OBD I code 67 - Neutral Drive Switch Circuit Open ( key on , engine off )