ETM fix?

[Frisbee78]

Hi all,
I live in sunny Scotland and unfortunately, here, we have not had the privilege of seeing the warranty on our ETMs extended to 10 yrs/200000 miles.

So, not really fancying paying through the nose for a new ETM just because a couple of potentiometers worth 50 cents packed in, I came up with a possible solution (maybe) to get a new lease of life on my ETM.

Thanks to Don Willson's website (http://www.vexedvolvo.org/) explaining in great detail the root cause of the problem, I figured that if one could restore the contact between the wipers and the resistor film despite the groove marks left by them, then one should be able to restore their ETM to working condition.

My suggestion to achieve this is to spread the area of contact between the wipers and the resistor film by means of an appended tip to the wipers (see attached schematics), thus restoring a reliable contact between the parts. The increased contact area should also slow down the wearing process, though of course, it will not completely suppress it.

My hopes are that this fix could provide a further few thousand miles of motoring until the resistor film wears out completely and the ETM unit finally need replacing.

If you think this is fix is not realistic, you're probably right. My concerns are as follows:
1. By replacing the 4 narrow contacts by one large one, the potentiometer will rely on this only point of contact to make a reading. I reckon that the original design of 4 points of contact was made in that fashion so that between all these points of contacts, there should always be at least one with an accurate reading, thus ironing out any glitches caused by the other wipers. However, with only one point of contact, this new potentiometer could send enough glitches to the ETM

[mom]

Interesting to see people trying to solve this problem on our ETM.
A couple of weeks ago,I was thinking about that and I began imagine something that could possibly do the job. It's not as easy as the solution of my predecessor but it should give inspiration to Volvo.

No need to redesign the components around the ETM neither on the ECU. Only replace this famous thick film by the one I propose:



Copper is by far more resistant and can be gold plated.

[Bud]

Unless I am mistaken, the new ETM that Volvo installs, has 10 wiper fingers, instead of the 4 on the original part. Perhaps we do not have enough history with the new part yet, but some early indications are that the new part can fail as soon as 12K miles. Not sure yet if reliability has been improved?

Check DonW's www.VEXEDvolvo.org site for additional details.

[Atsushi Hirano]

Hi, I bought 1999 S70 161000km last month.
I've already experienced ETS warning lights on and rough idling twice last week, so I tried to fix it by myself.

Material needed: Alminum foil from kitchen

Method:
1. Remove ETM from the car.
2. Open circuit board cover using screw driver (-).
3. Remove black colored adhesive which covers contacts between circuit board and left/right end cap using tweezer.
4. Cut contacts at the middle of each contact.(Since circuit board and end cap's contact is spot welded, not soldered, I could not unsolder.)
5. Open each end cap. Motor side end cap cannot be detached because the wire of the coil connects end cap to the main body. Carefully open to avoid cutting the wire.
6. Try to push plastic collar in the end cap by finger. If you can push it, it means there are some gap between the back end of the collar and the end cap's wall. Try to push and rotate the collar, then you may notice it will not push back. This means "the wiper is derailed from the groove on the register carbon, and contacting to the unused surface of the carbon".
7. Fold small amount of alminum foil and put it to the D shaped shaft end to make fitting of the shaft and collar tighter.
8. Return end cap.
9. Solder contacts.
10. Flatten circuit board cover and put it back. Then seal by sillicon sealant.
11. Attach it to your car, and go test drive.

So far problem disappear in my case.
I'm not sure if this will work for you, so please try by your own risk.
Thank you!

[MadeInJapan]

Thank you Atsushi...I hope your problem does not return.

どうもありがとう！　　ETMが　本当に　直ったか教えて下さいね！　

MIJ

[shgadam]

Hi all, just paid