I just bought a 99 V70R with 51K on it. Can anyone tell me specifically what fails when the throttle body problem occurs and whether there is preventative maintenance that may avoid the problem? Thanks.

There is a little electronic "wiper" that wipes across a piece of resistive material. It is basically a variable resistor. The resulting electrical signal is used to drive the throttle plate, I believe.

Well, a guy did a failure analysis on broken ETMs and found that the wiper was wearing a groove in the resistive material, until eventually it stopped working. Every time you step on the accelerator or change your position on the gas pedal, the wiper wears the resistive material more. City driving (more throttle changes / mile) = faster failure. Highway driving makes for slower failure, but it will still go.

When it fails, the car may suddenly (and without warning) just stop. Not good if you're on the highway or trying to pull out in front of a big truck. If you see the ETS light come on.... heed the warning and get it replaced, even though it will cost $1,000.

There is no preventive maintenance you can do. The wiper is completely sealed inside the throttle body unit.

Failure doesn't seem to have anything to do with cleaning the throttle body, which many people have tried with limited success.

http://www.volvoxc.com/forums/showthread.php?t=4875&page=10&pp=10&highlight=throttle

Good luck

Hello VEXED and prospective VEXED members,

As you may know VEXED (Volvo Enthusiasts eXposing Egregious Design) is the name selected for our efforts to strongly encourage (read “force”) Volvo into a recall of the electronic throttle module used on 1999, 2000, and 2001 70 and 80 series automobiles. This addresses the wearing out of the throttle position sensors and not throttle body cleaning. See http://www.volvoxc.com/forums/showthread.php?t=4875&page=4&pp=10&highlight=throttle and read the threads and the attachments to my postings.

We really need more names to join this protest.

On March 14th I sent a 1-pound package of failure analyses, postings from Volvo interest forums and about 100 complaints posted on NHTSB’s complaint web page. I asked for an answer by April 1st. April 4th, I received their answer. As you could guess the answer is, in so many words, ‘if it is not in warranty you are out of luck.’ So, by my interpretation, this means we are free to pursue other avenues of regress.

Many of you have asked what you can do to help:
As I have mentioned before:
Send complaints to NHTSB and Center for Auto Safety.
If you want to be included as members of VEXED, send you name, address, car make and model, and a short statement of your ETM failure, where, when, mileage, cost, etc. Send it to VEXEDvolvo@comcast.net, ( I just learned how to use Bcc, so even though I send messages out with many addresses you only can see yours and VEXED Volvo.) We are not to the class action suit yet but I will be sending information to NHTSB and asking my US Senator to ask them to get on this safety problem. I will still be posting at volvoxc.com but we don’t read them every day.
We did find that there were over 517,000 1999, 2000 and 2001 70 and 80 series Volvo sold world wide and 250,000 sold in the US. Now if we just knew how many ETMs were sold by Magneti Marelli we would have a stronger case.
Can you get me parts? See http://www.volvoxc.com/forums/showthread.php?t=4875&page=11&pp=10&highlight=throttle and page down to 105, or go directly to http://www.volvoxc.com/forums/showpost.php?p=46575&postcount=105
You might be able to get an out of warranty devices from the dealer but an independent garage might be more likely.
If you would like to include a picture of Abraham Lincoln to help with postage and printing expenses it would be appreciated.
I will keep you updated on our efforts as they are firmed up.

Don Willson
VEXEDvolvo@comcast.net

Many thanks for a clear explanation. Why would Volvo use a 40's technology gas tank sending unit when there are dozens of high-tech sensors available? I like analog, but this was a stupid choice. I would think the safety issue alone would force a recall. Thanks again and I will keep my fingers crossed when passing.

Some people talk about a touch-free Hall Effect sensor in other throttle bodies (that is, throttle bodies used by other car manufacturers - not Volvo). I'm not sure how they work, but anything that doesn't touch would have to be better.

My condolences on owning a 1999.

A hall effect sensor is basically a non-contact proximity switch. Then moving object has a magnet mounted on it and when it passes by the hall effect sensor it trips. It can be wired for normally open or closed operation.

IT'S AN INTERNAL COMMINUCATION FAULT. ALL YOU CAN DO IS PRAY, AND UPGRADE TO THE NEW STYLE

I hear that the "new style" is the same exact thing as the "old style"...difference is that the "new style" has a yellow sticker on it and not a white one...It's still destined to failure in 50K+ miles, give or take a few 10K miles depending on driving habits.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon