Introduction to Mode 06 Information Uses

An introduction to mode $06 Presented by AtuoService Tech.com copyright 2008 by peter F. Meier This presentation is an introduction to the generic uses of mode $06 information. And applied to pre-CAN vehicles only. For more complete information and examples, please visit us at www.autoservicetech.com/ technicallyspeaking.html A customer with a "Check Engine" light on... what does it really mean? Simply stared, it means the onboard computer has run a test or series of tests and found something it didn't like... The ECM (engine control module) is responsible for monitoring all systems that may have an impact on emissions... the ECM (engine control module ) is responsible for monitoring all systems hat may have an impact on emissions... and performs 3 basic types of test... Circuit integrity, functional and rationally circuit integrity tests for opens and shorts to power or ground. In a functional test, the ECM operates a component and uses the info from another component or sensor to see if it works. A rationally test is the ECM comparing one input to another to see it they make "sense". Knowing what type of test failed can provide diagnostic direction when looking for a fault. Each subsystem has its own ground of test... may be only one test for that system, may be several. These groupings are listed on the scan tool as "monitors" and may be continuous or non-continuous in operation. Tests for misfire, fuel control and component tests are "continuous". All others like the EGR, EVAP and oxygen sensor (to name a few), are "non-continuous". All are geared to making sure the catalytic converter is fed the proper gasses so it can do its job. The individual test results for the non-continuous monitors are found in mode $06. Let's start by seeing what the computer failed... commonly called "pulling the codes". On an aftermarket scan tool. I like to start with Global OBD2. Advantages: * quick hook-up * "real" data in the current data stream First stop" Check the status of the monitors. It they are incomplete, the mode $06 results are suspect. Monitor results that look like this... can mean that the ECM memory has been recently cleared and/or the conditions needed to run the monitors have not been met. Loss of battery voltage either due to the cables being disconnected or from a weak battery can also cause the monitors to reset now let's see what the codes are... this is found in mode $03 (stored codes) and mode $o7 (pending codes) This is a code set as part of the catalytic converter monitor... it is a "functional" test checking the converter's oxygen storage capacity. This monitor uses information form the upstream and downstream oxygen sensors... oxygen sensors are really nothing of the kind... but that's a whole 'nother' story... Simplifies, the ECM monitors their signals and when the two "mirror" each other, it assumes the cat is not able to do its job and sets the code. But since the ECM is using the sensor signals, any factor that affects these signals can cause a "false" code to set. Examples: * weak oxygen sensors * misfires * Exhaust restrictions all can affect the sensor signal and fool the ECM... That's one benefit of using mode $06... We can see what the test results were for diagnostic direction... let's go there now... first on this scan tool is selecting "special tests"... from there, we can select mode $06 some scan tools will list all the test results on one screen... This one lists them one at a time... most generic scan tools will show results loke this one. Let's take a look at what it means... first, numbers beginning with ($) means it is a hexadecimal number... a "computer speak" number that we don't need to worry about. Now, to understand what the items on the screen represent... starting with the top of the screen. Test ID, or TID, is the identifier that tells us what monitor this test is a part of. Component ID, or CID, is the identifier for an individual test in that monitor. There may be on or several... Next are the test parameters and results, shown as Maximum Minimum and Measured. Max and Min are the test thresholds and may be a number or "0". If "0", there is no maximum or minimum test value for that field. Then, a pass/Fail statement and the module ID... typically the ECM. Let's look at the screen again... For this test, there is no Minimum...only a Maximum. Which was exceeded so the test "failed". The questions are: what is this test? What do the test results mean? For that, we need information... Test descriptions are getting easier to find. In aftermarket service information, or straight from the OEM you can find a link to OEM info at: www.oem1stop.com and www.nastf.org using that information, we can find out that this test... and this one... are test of the two oxygen sensors and their sensors and their ability to switch from high to low... the test results also show they passed. One of the drawbacks to mode $06 you don't know how "current" the test is... it depends on when the monitor last ran. A monitor will not run unless all the conditions needed to complete the tests have been met. Including how the car is driven. Another factor to consider... sometimes test results will not be updated unless the test results are worse, or the test fails. The numbers listed in the test results also have to be converted to actual data... some newer scan tools do this automatically. This one doesn't... we also don't know what the units of measurement are... they could be pressures, vacuum, percentages, voltages, or amperages... Just to name a dew. Back to the service information... can you see what the test shown in the previous screen is for? This is also a catalytic converter test... the ratio of switches between the two oxygen sensors is monitored, and when it exceeds the maximum, the test fails. To convert this particular test, multiply the number on the screen by .0039. This number is ratio. Max allowed is .74, the test result was .80. Caution! Conversion factors, test and component IDs are unique to manufacture. CAN address many of these issues. Now we have real data to work with and an idea of how the ECM is testing this system. I can use this information in designing my own diagnostic tests. I can also use this information to see if any test was CLOSE to failing when looking for an intermittent problem. A good use of mode $06 s to verify your repair. After all, who is going to test more thoroughly... you or the ECM? By clearing the information and rerunning the monitors, I can get the ECM to test my repair for me. Have a ford (or ford product like Mazda and jaguar with a misfire you can feel and no code? Ford was good enough to include misfire test results for individual cylinders in mode $06 it looks like this. Multiply the test values by .0015 to get a percentage of misfires per cylinder. Complete details can be found at www.autoservicetech.com In the example, the test limit translates to 20%, and the measured value is 2.5%. I know that 22% is a type a thresh-hold typically at idle. But the 2.5% is close to, if not over, the thresh-hold for type B misfires. While the test may have "passed", I know this cylinder has a problem. By going to mode $06, I can ID what cylinders are misfiring, even when diagnosing a "random misfire" code. Mode $06 is not a "sure cure" but another diagnostic aid. Benefits: *Diagnostic direction *Repair verification *Understanding ECM test strategy Drawbacks: *"Old" data? *Need to translate/convert info *Need to ID test and associated monitor all of which getting easier. So the next time you see one of these... take the time to do a little homework $06 might tell you. It may save you time and resolve you problem faster. We hope you enjoyed the presentation. Thanks for watching!