How does the OBD-2 diagnostic interface work?

If the vehicle’s onboard diagnostic system detects a malfunction, a DTC corresponding to the malfunction is stored in the vehicle’s computer, as well as realtime data from the sensors connected to the on-board computer. In addition, the OBD-II interface provides a means to clear the DTC’s once maintenance has been completed.

When was a diesel engine required to support OBD?

Diesel (compression ignition) vehicles were not required to support OBD until 2004. Some pre-2001 petrol vehicles and pre-2004 diesel vehicles have a 16-pin connectors but they may not be OBD-II or EOBD compliant. Where is an OBD II connector?

How to read Check Engine light ( OBD-II ) codes?

The scan tool will power up as soon as it has been plugged in. Step 3: Read the codes in the computer. Each scan tool will have different instructions on how to operate it, so read yours carefully. Navigate to a heading called “Read Codes” and select it. Step 4: Record the codes that display.

What should the overall resistance of the OBD-2 be?

Due to the combined resistance of the two termination resistors at 120 Ohms each the overall resistance should be read as 60 Ohms. OBD-II provides access to numerous data from the ECU and offers a valuable source of information when troubleshooting problems inside a vehicle.

What happens when OBD 2 system detects problem?

If the OBD II system has detected a problem, the vehicle owner would be expected to have the problem repaired in a timely fashion. Correction of the problem would be verified through the OBD data transmitted after the vehicle has been serviced.

What should the voltage be on the OBD II scanner?

With the ignition key ON and no bus activity, BUS + should read 0V BUS should read 5V With the ignition key ON and bus activity, the voltage should vary from 0 to 5V depending on the amount of bus activity! ADDITIONAL NOTES PCM receives battery voltage (B+) through a fuse or fusible link. Check for an open circuit.

How to check for OBD-II DTC Bank 1?

Inspect all vacuum and PCV hoses, replace/repair as required Inspect all hoses and connections in the air intake system Inspect and/or test the intake manifold gaskets for leakage Check for a dirty fuel filter and proper fuel pressure Ideally you’ll want to monitor short and long term fuel trims using an advanced scan tool

When does the Universal OBD-II drive cycle begin?

The universal OBD-II drive cycle begins with a cold start. You should have coolant temperature below 50 C/122 F, and the coolant and air temperatures within 11 degrees of one another. This condition can be achieved by letting the car to sit overnight.