Troubleshooting EFI Cars - Scan Tools And Trouble Codes

You can read the trouble codes with a scan tool and the proper connectors.

Common Problems
Stein and Mana stressed verifying the proper operation of the electrical and mechanical parts of the system in question because, in many instances, the electronics are working properly. "Most of the driveability problems I see are caused by vacuum leaks, which can trigger lean fuel misfire DTCs," Stein tells us. Mana related a similar story: "I've worked on cars with plugged fuel filters that triggered a random misfire code. On the scanner, the pump was delivering the proper fuel pressure, but the filter was so plugged, the pump couldn't deliver the proper volume of fuel, especially under heavy load." He also tells us about an Escalade a customer brought in with random misfire and faulty MAF sensor codes. Rather than automatically replacing the MAF, he checked the air filter and ducting and found a giant rat's nest clogging the inlet to the airbox. "You've got to treat the scanner as another tool to use while diagnosing problems, not as your only source of information," he says.

More often than not, it comes down to experience. The more you know about how a component or system is supposed to work, the easier it will be for you to figure out how to fix any problems that arise. The more you work at it, the better you will be.

Here's a 10-pin GM OBD-I connector. Jump pins A and B to trigger the ECM's self-diagnostic procedure. You can read the trouble codes by counting the number of times the check engine light flashes.
Here's a 10-pin GM OBD-I connector. Jump pins A and B to trigger the ECM's self-diagnostic
All OBD-II cars share the same connector.
Here are oxygen sensors before and after the catalytic converters verify the cats are working properly.
Here are oxygen sensors before and after the catalytic converters verify the cats are work

The Actron 9185 Elite scan tool.
Galpin Ford's Johnny Stein demonstrates Ford's Integrated Diagnostic System, a PC-based ECM scan tool. It is available to retail customers but is very expensive and requires annual renewal fees. You also have to upgrade it every year, and that isn't free. Stein guesses he's invested nearly $4,000 of his own money to pay for his equipment.
Galpin Ford's Johnny Stein demonstrates Ford's Integrated Diagnostic System, a PC-based EC
You don't need to buy the latest, most expensive scan tool on the market, but we do recommend buying one that will read your car's data stream. Look to spend about $200. Some parts stores may have a few available to rent if you want to try one out before buying it.
You don't need to buy the latest, most expensive scan tool on the market, but we do recomm

We found the book How To Use Automotive Diagnostic Scanners by Tracy Martin to be especially useful, with lots of great information on how onboard diagnostics work and how to use the car's data stream information to diagnose driveability problems.
We found the book How To Use Automotive Diagnostic Scanners by Tracy Martin to be especial
Look up the trouble code and follow the diagnostic chart in the service manual.
DTC code descriptions are available at Actron's website. We also recommend buying a factory service manual for your car.
DTC code descriptions are available at Actron's website. We also recommend buying a factor

SOURCES
Actron	Motorbooks
Cleveland, OH	Osccola, WI
800/228-7667	800/826-6600
actron.com	motorbooks.com

Galpin Ford	Westech Performance Group
North Hills, CA	Mira Loma, CA
800/256-6219	951/685-4767
galpinford.com	westechperformance.com