The real cause of VOLVO Electronic Throttle Failures

To the Service Manager:

Added December 22, 2006 - NHTSA final report on Volvo ETM Defect Investigation

Added November 22, 2006 - Volvo announces Recall Campaign 155 to upgrade software.

Added June 1, 2006 - SMB 25 156, Warranty; SMB 25-155 Software Upgrade; and TNN 25-149 A through E dated March 2006 are now the defining documents.

Added January 2006 - TNN 25-149A - In the Volvo ETM/ETS troubleshooting document. It also list all other documents related to diagnosing, repairing and replacing the ETM.

Added December 2005 -- As you now know, Volvo Cars North America has extended the warranty on the ETM to 10 years and 200,000 miles. You can see parts of 2 documents on the "Extended Waranty" page. According to the Air Resources Board - California, letters to all owners of the subject cars were to be sent on December 5th.

If you have a customer with a  ETM replacement, call your support contact at Volvo, and they will give you authorization to repair the car under the extended warranty.

You and your clients have been plagued by failures of the electronic throttle modules (ETMs) and Volvo has not provided you with information on the real cause of the failures. As a result you are ill informed and wasting your time, your customers money and losing customers. I realize this simple replacement is a cash cow for you but at the expense of many unhappy customers. 

To the best knowledge of the VEXED Group, Volvo has never given you any guidance on the problem or told them the real cause of the failures. The real cause being the wearing out of the potentiometer films in the throttle position sensors.  The only thing is an early TSB that says to clean the throttle bore. This is the basis for a ‘secret warranty’ lawsuit http://www.fazmiclaw.com/Volvo.html. It is commonly thought that this is to get the car past the 4-year, 50,000-mile warranty before the TPS fatally fails. The failure is very intermittent in the early stages so that coincidentally cleaning seems to work.  

What is NOT the cause of failure

As early as 2000 these failures were beginning to appear. Without a complete failure analysis the diagnosis is a hit or miss affair. Complicating the diagnosis was the intermittent nature of the failure, from intervals of daily, weeks or even thousands of miles. As yet, no one has uncovered any evidence that Volvo gave the dealers and guidance or instructions as the real cause of the failure, but let them each do an ineffective job of troubleshooting. This of course caused the customer time, money and aggravation, and not a few lost loyalties. This can be summed up in " It is like treating their dealers and customers like mushrooms: keep them in the dark and feed them on that stuff that starts with B and ends with T".

In some cases it seemed that excessive black gunk built up was causing a 'sticky' throttle that responded to cleaning of the throttle bore. The reason this seems to work is that in the early stages the failure is very intermittent and the fact that cleaning is helpful is purely coincidental.

Oxygen sensors were sometimes identified as the culprit.

As the air mass meter is also an input to engine management, changing it sometimes seemed to be the repair, until the next intermittent failure occurred.

One mechanic reported a 'wallowed' out throttle shaft bushing that let un-metered air enter the throttle. Of course replacing the ETM fixed the problem but for the wrong cause. (The throttle shaft rides in two double shielded precision ball bearings so this cause is highly suspicious.) 

A person reported that his previously owned car had the ETM failure. His independent mechanic found that the injectors and spark plugs had been changed, probably as a shotgun approach to fixing an ETM failure.

Of course 'bad' and 'cheap gas' is an unidentified source.

Not having the vehicle serviced by a Volvo dealer.

One dealer accused the owner of lack of periodic maintenance. This was patently false as the owner’s records showed perfect adherence to the recommended maintenance schedule, with all the service being done by that dealer.

Another, reported by an independent Volvo garage, that I have yet to check out, is oil in the end caps. For this to happen oil would have to enter the end caps around or through the bearings. Since, in non turbo engines the throttle bore is always under negative pressure, it could only happen with turbo engines, that pressurizes the engine intake, including the throttle. Another clue is that is appears to happen on poorly maintained engines where the nipples on the EGR valves were clogged causing oily blow by to enter the intake.

Often quoted is. “It’s the electronics.” It is very unlikely to be caused by the electronics. The actual electronic components, if they make it past the first 100 hours or operation should literally last forever. As the manager of an electronics failure analysis laboratory we seldom saw electronic failures unless they had been over stressed (plugging a 115 volt bulb in a 230 volt socket) or ill designed. Most failures of electromechanical devices were due to failures of the mechanical (read 'moving') parts. The truly electronic failures usually show in within the 'burn in" period of 24 to 48 hours.  
One Volvo Customer Care specialist even said, " These are high tech cars, what would you expect?

I am sure we will pick up more horror stories at the information gets out. 

The replacement part is of the same design and it too will fail. I have reports of owners replacing the ETM 3 times at an approximate cost of $1000 each time and several experiencing 2 failures. 

In early March, 2005, I sent a one-pound package of my reports, about 100 incidents reported to NHTSA, and many postings from the Volvo related forums to Susan Campbell, the Assistant Manager of Customer Service, who said she forwarded my analysis Engineering at Volvo. A couple of weeks later I received the following reply from her, “We feel that our 4 year 50,000 mile warrant is sufficient, after that we can provide ‘for pay’ service”. My reports have been reviewed and certified accurate and a true analysis of the failure by a Registered Professional Engineer in Colorado.

Replacing the ETM is a dealer repair since proprietary VADIS (Volvo After- sales Diagnostic and Information System) software must be uploaded. Some independents have now purchased VADIS though you will probably not find it at an independent garage that does not specialize in Volvo cars.

Refer to the Technical section of this web site to see the location of the throttle position sensor, a thick film potentiometer, and a complete description of the failure. 

After you have studied my reports I hope you are very curious as to why Volvo is hiding this information from you. I have several ETMs that I have studied and more are on the way from the VEXED Group. If you need additional information let me know or would like to be kept up on developments of VEXED activities send my your E-mail address to VEXEDvolvo@comcast.net. VEXED encourages you to contact your service specialist at Volvo Corporate and ask them what they are doing to assist you in serving your customers. Be sure to mention VEXED. 

A final thought. Many of your customers have checked the numerous Internet forums discussing Volvos and are very knowledgeable about this failure. Any response to them other than the truth will not be received well. (Note: on May 21, 2005, I sent a slightly longer version of this page to over 100 dealers in North America. Several days later one of the VEXED Group alerted me to the fact that all e-mail addresses had been removed from the “Find a Dealer” portion of the Volvo web site. Is this only a coincidence or was there something they did not want you to see?)

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