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-   -   Volvo XC90 rpm sensor location (https://www.volvoforums.org.uk/showthread.php?t=312142)

Doombug11 Nov 29th, 2020 15:34

Volvo XC90 rpm sensor location
 
Hi all, my car won’t start and I’m getting an error code with the rpm sensor (ECM-3100 in VIDA) only problem is I can’t locate it!! Anyone out there able to help lead me towards It? I recently replaced the starter so I reckon there’s a good chance I’ve knocked something round there.

john langrick Nov 29th, 2020 17:28

Hi, I think it is actually called the 'crankshaft position sensor' this video will help locate it.

https://www.google.com/url?q=https:/...HHZIMm2QmWbJ1U

It counts pulses generated by the teeth on the flywheel.

When mine failed on my old V70, the plastic mount had broken and the end actuall got trashed by the flywheel itself.

It is pretty easy to replace.

I also at another time had problems with bad connection into the sensor. You may have knocked this off.

A tell tale symptom besides the error code is that the tacho reads nothing when cranking. Understandable I guess.

Hope this helps

John l

Doombug11 Dec 2nd, 2020 00:35

1 Attachment(s)
Thanks for the reply, I suspected that was what I was looking for however the little bugger is still eluding me! I’ve taken the air box out to get better access but I still can’t find it.

It was an odd fault, I had recently changed the starter motor and plugged in Vida afterwards, cleared the codes took it for a drive and everything was good. Then the other night I started the car up and left it to warm up an defog for 5 minutes. All of a sudden it just cut out and would just spin over without starting.

The only new code is ECM-3100 Which is the rpm/crank sensor, oddly it only gives an orange indicator not red? The fault trace also says the sensor doesn’t need replacing. I just want to find the connector for this sensor so I can clean and reseat it before I do the next step in Vida!:laughing-smiley-018

Dancake Dec 2nd, 2020 01:42

Details of the car. Year, transmission, engine etc. If it's a D5, the crankshaft position sensor is located at the top of the transmission in a bracket that's bolted to the engine. It's pretty much top dead centre and can be a little tricky to access. The electrical plug faces the front of the car. Because the fault started after you replaced the starter, I would inspect the wiring going to the crankshaft sensor to make sure you haven't damaged anything in the process.

The starter motor earths through the brushes and into the engine block/transmission housing. When changing the starter you should have noticed the little locator stud on the replacement starter. Was it clean and free from dirt and corrosion before you fitted it? The same goes for the hole that the stud goes into. Also were the mating surfaces between the starter and transmission clean? A bad earth can give crankshaft position sensor fault codes because of the electrical interference, and will stop the car from starting. It's worth checking all of your earth connections to make sure they're good.

Doombug11 Dec 2nd, 2020 04:44

The cars a 2006 XC90, D5244T4, M66 AWD. Thanks very much for your reply! I pulled the starter from a scrapped D5 down a local Volvo scrapyard and was in a rush to get my car moving so just straight swapped it. Now you mention it the starter I pulled is a bit dirty and those locator lugs were quite corroded so before I go any further I’ll take it back off and give it a really good clean! Didn’t think they could be an earth source, thanks for your help.

Dancake Dec 2nd, 2020 05:05

A soft steel wire brush should get rid of the bulk of the corrosion, and you can use a bit of scotchbrite to clean the mating surfaces before bolting the starter on. If you were picky you could inspect the carbon brushes when you remove the starter to make sure there's plenty of material left on them. It would also do no harm to clean the commutator with some fine sandpaper whilst you're in there.

Doombug11 Dec 2nd, 2020 23:07

1 Attachment(s)
So I removed the starter and the mating service/ lug were filthy, however after a good clean still no luck getting the car to fire. I went back into Vida to do the fault trace and this time I figured out a bit more of how the software works. So I found the link in fault trace that takes you to the guide to replacing the rpm sensor! Didn’t realise Vida did all that as well! Awesome bit of software.

It appears the EGR mixer needs to be removed to gain access to the rpm sensor? I’ve attached the image from Vida. That process looks a bit of a pig as says to drain fluid and replace gaskets, is it possible to get to the connector to the sensor without going through that?

The fault is also specifically ‘faulty signal’ not ‘signal missing’ and advices either poor connection or oxidation of parts just as you were saying. I am much happier with how I’ve fitted the starter motor though now :)


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