Very Technical Information
NHTSA's information
request letter to Volvo Cars North America
In July
28, 2005, National Highway Traffic Safety Administration
sent Mr. William Shapiro, of Volvo Cars North A, an 8-page
letter requesting information about the subject cars and all
of the modifications to the ETM. You can retrieve it at:
http://www-odi.nhtsa.dot.gov/cars/problems/defect/defectsearch.cfm
Under
Quick Search enter “PE05041’ for the NHTSA Action Number
Click
on ‘Document Search’
Open
the 2 documents in Adobe Reader.
(I did
not know there were so many definitions of “document’.)
The following is a summary of links
that bring some clarity to the throttle position sensor and
the emphasis on the fact that potentiometers are not
suitable for this application.
The
first ETM failure reported to NHTSA was for sudden
acceleration though generally surging, hesitation and
stalling are more often reported.
11/10/2003 - Royal Philips Electronics (Philips-Siemens) announced a new magnetoresistive sensor that will be launched in vehicles in 2004 for automotive angular measurement applications including electronic throttle control (EGAS).
http://www.embeddedstar.com/press/content/2003/11/embedded11375.html
The second paragraph says. “Today's
solutions for angular measurement (viz. potentiometers) in
applications such as throttle control are prone to failure
over time as the mechanical components of the sensors are
easily prone to wear and tear.”
http://www.alps.co.jp/e/technology/03/2003/dec/1.htm
This article is a good overview of
sensor technology in automobiles. It shows the construction
of a typical potentiometer and the characteristics of the
components. In part 4 is an explanation of the mechanism of
wear. Since they discuss wear, there is an admission that
wear occurs, in exactly the same way as seen on the Magneti
Marelli throttle module as used in the 1999 – 2001 gas
fueled Volvos.
http://www.alps.com/r_d/technology.html
click on "Advanced technology"
click on "Vol.9"
click on the right arrow at the bottom of the page to
get to section 4, "The mechanism of wear".
ALPS, Japanese Innovator of Electronic
Devices, say, “Alps has succeeded in developing a sensor
resistor that supports one billion cycles. Here they admit
to a much higher life than other potentiometers that
typically report life in the 10,000 to 10,000,000 range.
http://www.alps.com/r_d/technology.html
click on "Technology in our products"
click on "Components"
Here are two
products for throttle
position sensors. The first is apparently a potentiometer
and the second is a non-contacting sensor that is form, fit
and function replaceable for the potentiometer. So the
technology is out there. Note the first specifies a life of
5,000,000 to 10,000,000 cycles while the non-contacting
style shows life of greater than 5,000,000 and 10,000,000
cycles.
http://www.wabashtech.com/pdf/1036%20leaflet%20aw.pdf
http://www.wabashtech.com/pdf/1047%20leaflet%20aw.pdf
Though this does not apply to the 1999
– 2001 Volvos it does add some verification that a Bosch
system does exist. When discussing the accelerator pedal
module they say, “A potentiometer or contact-free sensor
registers the exact position of the accelerator pedal.” This
site shows the three pieces of the fuel system, the
accelerator, the throttle and the computer.”
http://rb-k.bosch.de/en/start/product_e_GS_01_EGAS.html
Owners Right to Repair Act
http://www.aftermarket.org/Government/Grassroots_Activities/hr2735.asp
http://www.theorator.com/bills109/hr2048.html
National Auto Dealers Association - Ethics Guide
http://www.nada.org/Content/NavigationMenu/MemberServices/Ethics_Guide/Guide.htm
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