Fault tracing a vehicle for intermittent faults

This procedure describes how to fault trace a VDS protocol-based vehicle when the probable cause for the customer's complaint is an intermittent fault. The procedure covers how you can use advanced functionality for DTCs when trying to reproduce a fault that does not exist in the vehicle at all times.

Note

This procedure is only applicable for VDS protocol-based vehicles.

The procedure is based on a case where a customer has a problem with her vehicle. A function does not work correctly from time to time. The customer told you that the last time the problem occurred was two weeks ago. The vehicle, an XC90 with model year 2016, is already connected to the VIDA workstation and DTCs have been read out. No CSC exists from earlier preplanning.

Add CSC to the work list

Expand the Work List menu item in the left-hand menu panel and select Customer Symptom Codes.

ð	The Customer Symptom Codes page is opened.

Type a search string in the search field for the CSC you need to add and press [Enter] on your keyboard.

ð	The CSC matching the search string you entered is shown in the right-hand panel.

Select CSC by ticking the checkbox and click the Add to List button.

ð	The CSC is added to your currently active work list.

Check the ranked list

To start fault tracing the vehicle, click Fault Tracing in the left-hand menu panel.

ð	The Fault Tracing page is opened and the CSC you just added to your work list is preselected. The pre selection generates a ranked list of the most probable causes of the problem.

You should always start with the first component or action in the ranked list and work your way down. Click the first action in the list, which in this case is a component test.

ð	The ranked list is replaced with a document containing an instruction of the component test.

Examine DTCs

Follow the instruction in the component test. In this case an automatic analysis is done and indicates that the fault is intermittent. By following the instructions in the component test you can see that you should use the DTCs tab to examine the DTCs in order to reproduce the fault.
Click the DTCs tab.

ð	Once entering the DTCs tab, the Confirmed tab is selected by default.

In this case you do not have any confirmed DTCs, therefore continue by selecting the Unconfirmed tab.

ð	In this case there is one unconfirmed DTC that could support you in finding the fault.

Click the title of the DTC to get more information.

ð	The DTC Information window is opened.

To check if the DTC is relevant for the customer's problem, select the Details tab.
Use the timeline to check if the fault occurred when the customer stated that the problem was experienced. The first and last occurrence is indicated by timestamps on the grey line.
In this case the indicated time of fault coincides with the point that the customer stated that a problem was experienced. Click the grey line in the timeline.

ð	A pop-up is shown.

Check the level of intermittency by viewing the grey area. Make an assessment if the fault has occurred with a frequency that makes it likely that the customer has experienced a problem. In this case, the data seems to be consistent with the information provided by the customer. Close the pop-up.

Run control module test

The next step is to test if a fault can be detected by the control module test. Click the Start button to the left below the Fault Counter indicator.

When clicking the Start button, the following indicators are updated:

Test Run
Test Result
Fault Counter

Check if the test starts in the Test Run indicator. The value in the Started row shall be Yes. Also check if the test starts in the Fault Counter indicator. The value shall be other than 0.

ð	In this case the test does not start.

Select the Overview tab to see the test run criteria.
Under the header Test Run Criteria you can see the criteria for the test to start. In this case you can see that the vehicle must be in usage mode Driving. This means that the engine must be started.

Start the engine and select the Details tab again.

ð	You can now see in the Test Run indicator that the test is started. This is also shown in the Fault Counter indicator; the value is now other than 0.
	If the Fault Counter indicator counts down, the fault is not active.

Check if it is possible to recreate the environmental and operational conditions that were present when the fault occurred in the vehicle. The following can be used when making an assessment:

Timeline:

Frequency of the fault i.e. the number of operation cycles with fault compared to total number of cycles. This information is accessed by clicking the grey part of the timeline.
Number of cycles since the fault last occurred. This information is accessed by clicking the green part of the timeline.
Frozen parameter values.

Fault counter:

Maximum value since DTC was erased last time.

Also try to reproduce the fault by e.g. jiggling wires to the component or by jiggling the component itself.

The frozen values can be used to identify the condition when the error occurred. Click the frozen values icon (⃟) in the Timeline indicator.

ð	A pop-up is shown.

If a frozen value is outside range it can be an indication that the component has been faulty during a certain time period or that faulty information from another component has been received. You can also see the parameter descriptions by expanding the parameter.

When you have read through the relevant parameters, close the pop-up.

If you manage to reproduce the fault, the Fault Counter indicator counts up, indicating that the fault is active.

The test result also shows when a fault limit is reached. In this case the Unconfirmed limit is reached.

The fault has now been reproduced and this is a strong evidence that the component pointed out by the DTC is faulty. When your evaluation of the fault is finished, click the Stop button below the Fault Counter indicator and close the DTC Information window.
To remove and examine the component you need to use the repair instructions. Find the repair instructions by opening the Documents tab.
Open the relevant document by clicking its title. Follow the instructions in the document.

Provide feedback

After repair and verification, give feedback on what helped you to solve the problem. In this case a fault was found, which means that feedback should be given by clicking the Fault Found button.

The status after a fault tracing is indicated by an icon in the ranked list. In this case the icon is shown since the fault was found. You can always change the status of the fault tracing by clicking the arrow next to the icon and thereby get a new ranking.

Erase DTCs

If you have multiple CSC you should now continue with the next one. In this case you only have one CSC, therefore you should now continue by erasing the DTCs. Select the DTCs tab.

ð	The DTCs tab is opened.

Click the Erase All button to erase both confirmed and unconfirmed DTCs.