Electronic Throttle System - Troubleshooting
NO: 25-149-ADATE: 07-07-2006
MODEL/YEAR:
C70 1999-2002
S70 1999-2000
S60 2001 all engine variants, 2002 non-turbo only.
V70 1999-2001 all engine variants, 2002 non-turbo only.
V70XC, 1999-2000
XC70 2001
S80 1999-2001
SUBJECT:
Troubleshooting Electronic Throttle System (ETS)
REFERENCE: VIDA
This Tech Net Note supersedes the previous TNN 25-149A dated 12-6-2005 and TNN 25-149A dated 04-03-06. Please update your files.
The two prior versions of this TNN offered background and fault tracing information for the Electronic Throttle System on the above vehicles. With the release of VIDA version 2006B the background and fault tracing information has been integrated into VIDA.
New Fault Tracing
The fault tracing for ETS codes in VIDA has been enhanced to include more background information on Faults sub system and the criteria for detecting a fault. Where applicable if there are differences between the original software's fault detection criteria and the new ETS software (March 2006 and later) the differences are described in the fault code information.
Design and Function
The Design and function section of VIDA described as Throttle Diagnostic has been enhanced significantly and offers an excellent description of the system and all of the involved components, including the interaction of and dependence between components for system function. This is worth reading as a refresher on the functionality.
Potentiometer Tool
Some of the ETS DTCs (9150, 9160, 91A7) may indicate that the signal value from the throttle position sensors was incorrect. One possible source for this fault is wear or aging of the potentiometers themselves. From VIDA 2006B, when following the fault tracing for these DTCs, the information suggests testing the potentiometers if counter 4 is higher than 10. The tool can be accessed by clicking the VCT symbol from the fault tracing, or by looking under the advanced tab for the ETM / Vehicle Communication. The tool will sweep the throttle potentiometers, closed-open-closed, four times while displaying the difference in values between the potentiometers.
The tool will only work with the latest ETM software, so it will need to be downloaded before the potentiometers can be evaluated. Please read the text in the test tool dialogue box carefully the first time to understand the ignition key and button combination needed to start the test. For VIDA 2006B, the test box will always have the wrong message along the bottom telling you the software needs to be upgraded, even if it has already been upgraded. Ignore this message. DTCs may need to be erased after the ETM has been allowed to re-set.
Combined Fault Code Matrix
As with the TNN, the fault tracing in VIDA now has links from the individual DTCs to a combined Fault Code Matrix, to enable root cause DTCs to be determined. The following statement:
"Of the above diagnostic trouble codes (DTC's), only the Electronic throttle module (ETM) can be a possible cause for the following diagnostic trouble codes (DTC's): 903F, 910E, 914F, 9150, 9160, 91A7, 91B7, 91F0."
was translated incorrectly and should be ignored, there are many possible root causes for these DTC's and the fault tracing should be followed.
Software Part Number Identification
In VIDA 2006B, guidance is given to identify the latest ETS software as a part of most of the fault tracing steps. However, due to the long lead times involved in publishing the VIDA information, the part numbers used for the turbo and 6-cylinder non-turbo vehicles are incorrect. (See below.)
From July 1st there will be a small change to the engine management software released for the turbo and 6-cylinder non-turbo vehicles as part of the ETS upgrade. In the initial versions released in March, 2006, a change was made to the idle air adaptation to better compensate for aging and normal dirt build-up in the throttle over time. Unfortunately, when the air adaptation was expanded, the initial value (starting point) was left as it was in the original software.
This may in some cases mean that a vehicle with a dirty throttle and/or breather system would require some adaptation by the technician to eliminate a surging idle before giving the vehicle back to the customer. This would also be necessary if the battery was disconnected or if any fault codes were cleared from the ECM; clearing the fault codes also clears adaptation values. To aid the technician in expediting ETS upgrades, from July 1st 2006 the ECM software component for these vehicles has the initial value for the air adaptation set to the median value, reducing the need for adaptation.
Upgrading to this later version may also help a customer who regularly disconnects the vehicle battery for storage.
Due to the software revision above, the software part numbers for the affected engine management systems have changed. The latest (after July 1st 2006) software can best be identified using the diagnostic part numbers in the Matrix shown. ECM software downloaded to all turbo and 6-cylinder non-turbo engines between 3/17/2006 and 7/1/2006 can be identified by the software part number in the matrix.