PMM JULY/AUGUST 2016 15

VEHICLETROUBLESHOOTER

DIAGNOSTIC TECHNIQUES

In this issue we’re going to lookthrough the diagnostic capabilities andusefulness of the Global OBD IIfunctions offered by the ESI 2.0

software, which can often be overlooked invehicle diagnosis.

The American OBD (On Board Diagnosis)standard was introduced in 1988 in Californiain an attempt to reduce traffic-related airpollution. OBD regulations involve self-monitoring by electronic control units of allvehicle systems and components whichinfluence exhaust emissions. In 1996 thisstandard was succeeded by OBD II to meetwith more stringent emission limit values. InEurope, EOBD (European On BoardDiagnostics) is based on the morecomprehensive OBD II concept and appliesto gasoline vehicles registered from01/01/2001 and diesel vehicles registeredfrom 01/01/2004.

System faultThe standardised OBD system enablesconstant monitoring of vehicle componentsinfluencing exhaust emissions. If a systemfault is detected that leads to an increase inemissions, the driver is informed accordinglywith a malfunction indicator lamp (MIL). Ifthe fault that is detected is severe enough tocause damage to a component such as thecatalytic converter then the MIL will flashand action can be taken, such as fuel injectorshut off by the control unit to protectcomponents at risk. Fault codes will be storedby the controller with a description of themalfunction and relevant information. Thefive digit OBD fault codes always begin with‘P0’ and have standardised descriptiondesignations for all VMs. For example ‘P0301’will mean ‘Cylinder 1 misfire detected’,

regardless of the vehicle make and model. For system analysis and fault finding, the

OBD system data is accessed via the 16 pindiagnosis connection to the Bosch KTS usingone of the five permitted communicationprotocols. The Bosch ESI 2.0 software offersthe Global OBD II (EOBD) diagnosis modeat the top of the ‘System group selection’ listfor every applicable vehicle selection (RBkey) (see Fig 1).

Typically the Global OBD II functionsconsist of diagnosis modes one to nine and inBosch ESI 2.0 there are also some usefulextra features (see Fig 2).

The first extra feature in ESI 2.0 on theselection screen is ‘Systems found’. This willdisplay compatible ECUs and usually lists theengine control and transmission control, if thevehicle has an automatic gearbox.

The next additional feature is the ‘On-board diagnosis overview’, which is a quickand accurate method to assess the state of thevehicle system and can provide essential datato help you find an emissions related fault.

Now let’s go through the nine OBD modesmentioned earlier:

This regular series of technical articles from Bosch focuses on how to get the best out of its ESI[tronic] 2.0 software, which is

used in conjunction with the KTS range of diagnostic tools for vehicle fault diagnosis and service function procedures.

�

�

ROBERT BOSCH

KTS DIAGNOSTICS MADE ‘ESI’PART 9: GLOBAL OBD II, EMISSIONS BASED SYSTEM DIAGNOSIS

�

015_PMM_JULY16_Layout 1 15/06/2016 11:35 Page 15

16 JULY/AUGUST 2016 PMM

Mode 1: reads the actual data that isprocessed by the ECU from the sensor inputsignals. The available data depends on thevehicle configuration and, in true KTS style,can be displayed in different ways to suityour preference. From the start, you’represented with a full scrollable list of valuesdisplayed as live readings. The standard OBDII PIDs (Parameter identifications), as definedby the Society of Automotive Engineersstandard – SAE J1979, are shown in the righthand column.

You may be surprised by the large amountof data available on some cars, such as DPF,NOx and SCR information on the very latestdiesel cars (see Fig 3). You can manipulateand filter the ‘Actual data’ list with severalmethods. Firstly, our good friend the ‘searchbar’ is present at the top of the data field.Typing any text into here will instantly changethe list to only display actual values thatcontain that text in their name (see Fig 4).

Scrolling listAll values are displayed on a scrolling list and,if you want to be more specific, you can selectup to any eight particular values by clickingthe ‘check box’ in the left ECU column andthen choosing the ‘Show selected only’ optionto filter out values you don’t want displayed.As we covered in a previous article, theselected OBD actual values can also bedisplayed in a colourful graph format by usingthe ‘Time profile’ F6 soft key (see Fig 5).

Some really useful values are usuallypresent in the OBD actual data program, suchas ‘Distance travelled while MIL is activated’and ‘number of warm up cycles since DTCclear’. This type of information can beessential if you have a problem vehicle with asuspicious repair history.

Mode 2: provides freeze frame data

associated to any stored DTCs which, ifsupported by the controller, can give a helpfulguide as to what the ambient conditions werewhen that particular fault was logged. This‘snap shot’ information is especiallybeneficial when testing for intermittent faults.

Mode 3, 7 & A: are grouped together toreport any stored fault codes, whether theyare confirmed, pending or permanent, alongwith associated readiness tests status (see Fig6). The fault code, status, description andtype are all listed. As the OBD II fault codesare standardised the information will bereliable and there won’t be any unknowndescriptions. The error memory can be saved,cleared or re-read directly using the soft keysalong the bottom of the screen.

Mode 4: is used to erase the fault codeerror memory for the OBD systems afterrepairs have been carried out. When the faultcode memory is cleared within the OBDsystem, the adaptation values and readinesstests are also reset. A specific road test (drivecycle) will need to be performed in order forthe OBD internal checks to be completed.Usually a fault code of ‘P1000’ will belogged until the internal systems OBD checksare satisfied.

Mode 5: provides more in-depth ‘Oxygensensor data’ and air/fuel mixture test results,but is not supported by all vehicle brands.

Mode 6: is the ‘Test data for monitoredsystems’ and gives useful information, such asLambda sensor parameters. Graphical displaybars of the values contain red and green

colour coding which give a quick guide as towhether the parameters are running withintheir tolerances (green) or outside them (red).Oxygen sensor and variable valve timing data,along with misfire counters, can be a realemissions fault finding aid (see Fig 7).

Mode 8: is the ‘Actuators’ function andcan offer on board system activations like anevaporative system leakage test, but thesetests may not be supported by all Europeanvehicles.

Mode 9: holds ‘Vehicle information’including the chassis number (VIN) andengine/automatic transmission control unitcalibration numbers and test conditioncounters.

Readiness tests: are the last selection onthe selection list and report the status of themonitor tests of either ‘ready’ or ‘not ready’and whether the test is ‘completed’ or ‘notcompleted’ (see Fig 8). This operation acts asa valuable confirmation of a successful repairto the system if all OBD monitor tests arecompleted and passed.

Soft keyAs with previous topics we’ve covered inthese articles, whenever the ‘Save’ soft key isshown along the bottom of the ESI 2.0screen, any data that is displayed on screenwill be added to the job ‘protocol’ report thatcan be saved and printed for reference.

In most cases the Global OBD II functionin Bosch ESI 2.0 gives you an additional wayto interrogate the vehicle power train systemsfor emissions related data. The methoddescribed here will sometimes give morespecific detail about the engine fuel trimanalysis, closed loop control and associatedcomponents that are critical to keep thevehicle exhaust emissions within theirprescribed limits.

VEHICLETROUBLESHOOTERDIAGNOSTIC TECHNIQUES

�

� �

015_PMM_JULY16_Layout 1 15/06/2016 11:37 Page 16

PREVIOUS ARTICLES CAN BE SEEN AT: WWW.BOSCH-WORKSHOPWORLD.CO.UK (UNDER ‘NEWS’)

OR BY VISITING: WWW.PMMONLINE.CO.UK.

The Global OBD II functions of ESI 2.0can be a great diagnostic aid when used tosupplement the specific engine controldiagnosis. We’ve seen some cars that willstore error codes in the OBD II memorywhich may not be evident in themanufacturer-specific ECU software. With

this in mind, it’s always worth checking theOBD II diagnostic functions within BoschESI 2.0 when you’re working on a vehiclewith emissions related faults, to ensure thatno vital data has been missed.

The OBD II capabilities within Bosch ESI2.0 and on board system test monitors

provide a more robust diagnostic processwhich can give you more confidence inreturning a fully tested and verified vehicleback to the customer after a repair.

To request further details about the range of

KTS diagnostic tools from Bosch circle 084

ᕧ ᕨ

015_PMM_JULY16_Layout 1 15/06/2016 11:38 Page 17