Are you as confident and

64 March 2007

BY BOB PATTENGALE Although Mode $06 is still a work in progress, it can be used to baseline a failure prior to repairs, then verify the accuracy of the diagnosis after repairs are completed. Photo montage: Harold A. Perry; visuals: Jupiter Images, Wieck Media and Bob Pattengale Are you as confident and efficient at diagnosing driveability issues as you d like to be? How do you know if the components or repairs you made corrected the problem? In many cases, Mode $06 can help confirm, rather quickly, if a problem currently exists and if the repair was successful. In this article we ll look at how Mode $06 can be used as a diagnostic resource. By now most technicians have at least heard of Mode $06 data, but many may still not know why it should be utilized. For those of you who are not Mode $06-savvy, let s do a quick review. The On-Board Diagnostic Second Generation (OBD II) standard created nine diagnostic modes. The Society of Automotive Engineers (SAE) defines Mode $06 this way: The purpose of this service (Service Mode $06) is to allow access to the results for on-board diagnostic monitoring tests of specific components/systems that are continuously (e.g., misfire monitoring) and non-continuously (e.g., catalyst system) monitored. The vehicle manufacturer is responsible for assigning Manufacturer Defined Test ID s for different tests of a monitored system. The latest test values (results) are retained, even over multiple ignition OFF cycles, until replaced by more recent test values (results). What does this mean to you? In the past, without Mode $06, technicians were basically blind to what decisions were made within the powertrain control module (PCM) to set diagnostic trouble codes (DTCs). Mode $06 allows the technician, utilizing an OBD II generic scan tool, to check the most current test results for various components and monitored systems. Mode $06 data is like having a view into the thoughts of the program engineer. Early OBD II vehicles report Mode $06 data as Test Identification (TID) and Component Identification (CID). The screen capture in Fig. 1a on page 66 shows Mode $06 data for a 1999 Toyota Tacoma using the Mastertech 3100 scan tool, and what TIDs and CIDs are currently available for this vehicle. You can quickly see TID $01-CID $01 shows up as a failure. The small screen is not able to display the actual test data. March 2007 65

Fig. 1a Fig. 1b Diagnostic scan tools will display Mode $06 data in different formats. The screen capture in Fig. 1a, showing the available TIDs and CIDs from a 1999 Toyota Tacoma, was taken with the Bosch/Vetronix Mastertech 3100. The right column notes Pass or Fail. By highlighting and pressing the tool s and Help buttons, additional data for TID $01-CID $01 is displayed separately, as shown in Fig. 1b specifically, the test limit and test values. Fig. 2 Early OBD II systems used the TID and CID formats. CAN-equipped OBD II vehicles will use the MID and TID formats. This screen capture from the AutoEnginuity scan tool shows converted CAN Mode $06 data for a 2006 Chevy Impala. Fig. 1b shows the details of TID $01- CID $01 after depressing the and Help buttons on the scan tool. We still don t know the definition of TID $01- CID $01, but we do know the maximum value should not exceed 128 and the current value is 255, which may indicate a failure. In this case, the TID and CID definitions will need to be retrieved from the Toyota service information. Both TID $01 and CID $01 relate to the catalyst monitor, which we ll discuss in detail later. Newer OBD II Controller Area Network (CAN)-equipped vehicles report Mode $06 data as Monitor Identification (MID) and Test Identification (TID). Fig. 2 shows an example of Mode $06 data for a 2006 Chevy Impala using the AutoEnginuity PC-based scan tool. The nice part about using a larger display or PC screen is that all the Mode $06 data can be displayed on one screen. Using this format saves time when reviewing the data. The key difference between older Mode $06 and newer CAN Mode $06 data is that SAE further refined the definition, unit and scaling conversion process. For example, prior to the new standards, Toyota established TID $01 as Catalyst Monitor; however, Ford established TID $01 as Oxygen Sensor Monitor. This can make the process of converting the data confusing. The newer SAE standard recommends vehicle manufacturers utilize MID $21 through MID $24 for Catalyst Monitor data to be uniform. The SAE HS 3000 On- Board Diagnostics for Light and Medium Duty Vehicles Standards Manual provides additional details. 66 March 2007

Fig. 3a Fig. 3b These are screen captures from the 1999 Tacoma using the Automotive Test Solutions EScan tool. Fig. 3a shows the raw data with no conversion help. Fig. 3b shows the converted data, which saves the technician from needing to look up Mode $06 data. Locating vehicle-specific Mode $06 data can be a little challenging at times. Each vehicle manufacturer uses a different format and location. Some (Ford, GM and Honda, for example) provide the data on the free portion of their service information websites, while others (Toyota, Nissan and Chrysler, for example) require you to pay for access to the data. In some cases the Mode $06 data is very detailed and useful; in others the charts are incomplete. The point here is that you won t know how useful Mode $06 data will be until you check the data. The diagnostic scan tool you use might do a lot of the work for you. Fig. 3a is a Mode $06 screen capture for the same 1999 Tacoma discussed earlier, using the Automotive Test Solutions (ATS) EScan tool. In the generic mode, the TIDs and CIDs are not defined and the test values are in the raw format. Fig. 3b shows the same vehicle with the Mode $06 data automatically converted. What if you had only the raw data and needed to convert it to useful information? The next step after using an OBD II generic scan tool to retrieve the Mode $06 data is to locate the vehicle manufacturer conversion data. In the case of Toyota, you d need to subscribe to the Toyota website to do that. For early Toyota/Lexus vehicles, the data was available on one PDF document. On later Fig. 4 Converting the raw Mode $06 data for the 1999 Tacoma shown in Fig. 3a requires a visit to Toyota s service information website. This chart shows the data necessary to convert the raw data for TID $01-CID $01. Toyota/Lexus models, the Mode $06 data is embedded in the DTC charts. Fig. 4 shows a sample of the data for TID $01-CID $01. The chart defines TID $01 as Catalyst and CID $01 as Catalyst Deterioration Level for Bank 1. The Unit Conversion column indicates how to convert the raw data. Fig. 3a shows the raw test value as 255, which means the test value needs to be multiplied by.0039 to obtain the true number of.994. The Max Limit is.499 (128 x.0039). The conversion does not change the ultimate results; the PCM has determined that the Bank 1 Catalyst failed the specific test. Once you know the actual definitions of TID and CID, converting the values may not be necessary. Mode $06 data can be used as a baseline to determine if a particular component or monitor now passes the test following repairs. Let s take a closer look at the 1999 Toyota Tacoma. This vehicle came in with the malfunction indicator light (MIL) on. We checked for DTCs and a P0420 (Catalyst System Efficiency Below Threshold) was retrieved. From past experience I knew that Toyota provided Catalyst Monitor Mode $06 data. Figs. 1a, 1b, 3a and 3b show the available Catalyst Monitor data. The Mode $06 results validate that the failure is active as of the last drive cycle. What happens next depends on your diagnostic strategy. I ve seen the following three different approaches em- 68 March 2007

ployed to attack this problem. Eventually, most shops will arrive at the same conclusion, but in several cases, time and money were wasted. Shop 1. The technician retrieved the P0420 trouble code and decided to clear it and drive the vehicle around the block to see if code came back. The DTC did not come back right away, so the technician recommended the waitand-see approach. The customer took the vehicle back and within a few drive cycles the MIL light came back on. If the technician follows the same procedure to verify the DTC, he ll end up with the same results. What happened? The technician did not follow the recommended DTC enabling criteria sequence in order to verify the problem. For this particular P0420 DTC, the following enabling criteria apply: battery voltage, >11 volts; air temp, >14 F; coolant temp, >167 F; vehicle speed, 31 to 50 mph; engine speed, <3000 rpm; time in closed-loop, >20 seconds (while driving, not decelerating) and no conflicting DTCs. The duration of the test is approximately 20 seconds, once the appropriate conditions are met. If the PCM determines that the test value has exceeded the limit, a first-trip fault is set. It will take two failure trips before the MIL comes on. If the technician does not follow these recommendations, the test will not run. A critical point here is multiple drive cycles: It doesn t matter how long this vehicle is driven; the ignition switch has to be cycled off at least once to run the second test. Shop 2. This technician followed a similar procedure, but decided to check oxygen sensor operation. The O 2 sensors reacted. But the vehicle had 150,000 miles on it, so rather than recommend an expensive catalyst replacement, the shop recommended new O 2 sensors. The same road test approach was taken and the DTC did not return, so the technician thought the problem was fixed. Fig. 5 shows the Mode $06 data after the oxygen sensors were replaced. The test value was lower (.604 vs.994), but this was still over the limit and only the first-trip catalyst test. If the vehicle had been released to the customer, it would have come back soon. Additional notes about Fig. 5: The DTCs were cleared after the O 2 sensors were replaced, which cleared the I&M Readiness Monitors and DTCs. In the lower left-hand corner, notice that the catalyst and evap monitors are not complete and the MIL status is OFF, but there s one pending DTC (P0420). The initial Mode $06 test is enough to elevate the P0420 to pending status. Shop 3. This technician retrieves the DTC and checks Mode $06 data, which Fig. 5 This Mode $06 data was taken from the Tacoma after the oxygen sensors were replaced. The test value improved slightly after the change, but was still outside the test parameters. The catalyst needs to be replaced. Fig. 6 This is Mode $06 data taken from the Tacoma after the catalyst was replaced. The catalyst replacement corrected DTC P0420 and the value is now within test limits. March 2007 71

Catalyst System Monitor Catalyst System Monitor B1S2 Heated Oxygen Sensor Monitor B1S2 Heated Oxygen Sensor Monitor Evap Vacuum Monitor.040 Leak Evap Vacuum Monitor.040 Leak Evap Vacuum Monitor.020 Leak Evap Vacuum Monitor.020 Leak Fig. 7a Fig. 7b The data shown in Fig. 7a was captured using the Bosch Diagnostics KTS-570 Bluetooth Wireless scan tool. A unique feature of the tool allows the technician to continuously monitor and chart Mode $06 data. This is useful when road-testing the vehicle following repairs. The screen capture in Fig. 7b shows the data from a road test taken from our test Tacoma after the catalyst was replaced. It took only an 80-second road test to verify that the catalyst corrected the P0420. confirms that the problem exists. Next, he researches the problem and follows the recommended service procedure, which recommends replacement of the catalyst. To confirm this repair the technician road-tests the vehicle following the enabling criteria recommendations. Fig. 6 shows the Mode $06 data after the catalyst was replaced. The Mode $06 test value is well below the test limit. All monitors are complete and there are no pending DTCs. This vehicle was properly repaired on the first attempt. The approach taken by the technician in Shop 3 can be used for virtually anything reported by Mode $06. Mode $06 test values create an excellent baseline target. The only downside is that for many vehicles the data is limited. But this is changing with the newer vehicles. Now here s a repair technique using Mode $06 that you may not have considered. If you live in an area where OBD II testing is performed, the issue of completing I&M Readiness Monitors can be difficult at times. I believe the key is not clearing the DTCs with the scan tool, which automatically resets the I&M Readiness Monitors, requiring extensive drive cycle time. It s preferable to allow the PCM to turn the MIL off naturally, which will normally take only two or three trips for many DTCs. The screen capture in Fig. 7a was taken from the 1999 Tacoma with the Bosch KTS-570 diagnostic scan tool in the OBD II generic mode. A really nice feature of this scan tool is its ability to request Mode $06 continuously and chart the data over time. Most OBD II generic scan tools do not offer this option. I wanted to be able to capture the Mode $06 changes as they occurred while I drove the truck, without having to watch the data closely. I already knew that the last catalyst Mode $06 test value exceeded the test limits, so the problem was active. I wanted to follow the enabling criteria for P0420 and see how long it would take to run the next test. The DTC was cleared. Fig. 7a shows that after 83 seconds of driving, TID $01-CID $01 changed from 0 to approximately 150 over the 128 limit. I repeated the test several times with similar results. Fig. 7b shows the road test after the catalyst was replaced. I repeated the same road test procedure and the test value increased slightly, to approximately 12, indicating replacement of the catalyst corrected the DTC P0420 test limits. In most cases, once the PCM sees two or three completed trips where the test value is within limits, the MIL should go out. The DTCs will erase after 40 warm-up cycles. In most OBD II programs vehicles don t fail for DTCs, only an illuminated MIL. In this Toyota P0420 example, the trips took approximately 80 seconds and I was able to turn the MIL off after three trips. If I had cleared the DTC and I&M Readiness Monitors, I would have spent approximately 30 minutes completing enough of the monitors for the vehicle to pass the state test. I can t guarantee this will work in all DTC situations, but it has saved me a lot of time. Mode $06 is a work in progress and it s getting better all the time. For some vehicle manufacturers the data is excellent, while others are working to improve its quality. The benefits of being able to baseline a failure prior to repairs and to verify that a test value is within limits after a repair is completed is priceless. It won t work in all situations, so you ll need to experiment with different vehicles to get comfortable. Options vary with each scan tool, so you ll need to pick one that provides the data and format you like. Mode $06 is one of many diagnostic options that can help you solve problems faster, so give it a try. Visit www.motor.com to download a free copy of this article. 72 March 2007