Other Articles - July - 2016

More than a Scan Tool to Diagnose an Acura

Any one that knows me will tell you, I love tools. Every time the trucks pull up to the shop, it feels like Christmas. The best thing about them, they make life easier on me, and having the right tool can make the difference between getting a job out the door today, or fighting with it for a week.

The fact that the best tools are very expensive, especially electronic diagnostic equipment, makes most people reluctant to purchase them. As for me, I know I will be in debt to Snap-on for the rest of my life, and will gladly pay the fifty dollars a week for all the new toys, oops, I mean tools.

Recently I got a call about a 2000 Acura Integra with erratic shifts and code P0730 (improper gear ratio). The technician had been working on it for over a week, using the most common and extremely expensive scan tool on the market. But the scan tool could only retrieve codes and had no option for data stream at all.

Having no data stream is a huge problem. It leaves you with only one option for diagnosis: backprobing sensors and solenoids, one at a time, in the hopes of finding the source of the problem. This can be a very tedious and time-consuming task.

After checking clutch pressures, manually checking solenoid commands, checking wires, and so on, he called me and asked if he could bring the vehicle over for me to check it out.

Though I have the same scan tool he had, I also have the Maximus 2.0 from Matco with the Launch software (figure 1), which I’ve found useful for import and European vehicles; second only to the OE scan tools and software.

It’s always a good idea to have more than one scan tool available. And they don’t all have to be expensive: I’ve seen times when a simple code reader was able to retrieve codes when the high- priced scan tools said there were no codes present.

We had several PIDs to look for in the transmission computer (figures 2 and 3). We took the vehicle for a test drive, watching everything in graph mode, and recording data. Within five minutes we noticed the countershaft speed sensor didn’t have a stable signal and would intermittently drop to zero. Honda sensors rarely fail, so my first thought was the erratic signal was probably a wiring harness issue.

After returning to the shop, we got out a sensor signal simulator (figure 4). This tool simulates predefined or user drawn signals. And it’s easy to use:

  • Probe the sensor signal wire (figure 5).
  • Connect the sensor simulator to the sensor signal wire.
  • Key on, engine off.

Now you can monitor the signal on your scan tool.

With everything connected, we could see a steady signal coming to the computer. Next step, wiggle test. Check that out (figure 6)… a dropout in the signal. This confirmed my suspicion of a damaged wire, and even narrowed down the location.

Turns out someone else had been working on the vehicle and damaged the wire harness under the intake manifold. We repaired the wire and took the car for a test drive to confirm the fix. That did it; total time spent? Thirty minutes. The time he’d have wasted — and money lost — diagnosing this one the hard way would have made a pretty good down payment for the right tools.

A sensor simulator can help you diagnose sensor problems in a wide range of vehicles, including Chrysler governor sensors, VLP sensors, and more. Some also have a multimeter function to check voltage, resistance, and frequency. It can save a lot of time and burnt fingers trying to backprobe connectors and sensors, and by feeding the signal straight into the connector at the computer, you can verify computer operation, bypassing wires and sensors.

The days of the FMXs, Powerglides, and seat-of-the-pants diagnostics are long gone. Today, having the right diagnostic tools can be the difference between making money and spinning your wheels. Scan tools, shift boxes, oscilloscopes, and signal generators are just as important as sockets and wrenches these days.