Can the ECU detect low oil 1998 v70 ?

[MrAl]

Here is a link to Our good friend Robert's video on crank sensor:



Here is the cam position sensor swap from Pelican parts:

https://www.pelicanparts.com/techarticl ... esting.htm

Apologies, it was the crank position sensor that was the issue on my 850, not the cam position sensor!

Neil.

Thanks for the link. It looks like you have to disconnect some stuff to get to the bolt. I'll have to look at mine when i go out there again.
I guess it may be ok i did not get any code for that, and Robert says he got a code for that that is why he was replacing his.

[scot850]

I never got codes for this on my 850.

Neil.

[MrAl]

I never got codes for this on my 850.

Neil.

Oh so it could be bad then...

[850oldschool]

Al, do you have a portable oscilloscope? With your electronics skills you might be able check it without even unbolting it.

[MrAl]

Al, do you have a portable oscilloscope? With your electronics skills you might be able check it without even unbolting it.

Well i can bring my laptop out there, but what do i look for?

[850oldschool]

Al, do you have a portable oscilloscope? With your electronics skills you might be able check it without even unbolting it.

Well i can bring my laptop out there, but what do i look for?

I've never had to mess with the crankshaft sensor, but I believe it's just a coil which is excited by a chunk of something ferrous whizzing by in close proximity. Kind of like a single coil magneto, I think? So you'd be looking for output pulses. A multimeter would probably work, but a scope would be more fun.

[MrAl]

Oh i see what you mean now. Yes, probably a variable reluctance sensor. They use those or at least they used to use those for sensing shaft position in various types of equipment including mail sorting and stamping equipment. Not sure how common they are anymore though sensors have improved a lot over the last 25 years. I would be they are very reliable though no moving parts other than the shaft they are sensing.
One way they were used was to detect the teeth on a steel gear that was mounted to a shaft. As the tooth swept by the sensor it would develop a voltage in the coil that would be detected by the electronic monitoring circuitry. That way each tooth would create a new pulse.

So now i know what to look for. I just hope the connector is not too hard to get to you usually have to be able to make contact with both terminals. That means pulling the connector off and still finding a way to connect it and the scope probe and ground too.

Thank you

[esl_97_850_T5]

1. I have *not* seen any Engine ECU DTC codes for Low Oil Level or Low Oil Pressure -- not for 98 S70/V70, nor for 96-97 850.

2. However, I believe the 96-97 850 had the capability to detect Low Oil Pressure and communicate that to the COMBI as a DTC code.

That being said, in the ~6-7 years I actively monitored submissions at jonesrh.info/volvo850/kwpd3b0_interpreter.html, I only encountered 1 day that some 850 manifested a Low Oil Pressure condition. That's very, very rare.

And in the ~8 years I drove my 850, I **never** encountered this (sustained) Low Oil Pressure situation, yet there were quite a few times when the oil level in my 850 was below 1 qt low and was probably even 2 qts low sometimes. I was astounded that the engine would continue to operate with seemingly no damage?!?! I began to understand why the engines are called BRICK.

I'm not certain if 98 S70/V70 had the Low Oil Pressure detection capability. I think it did, and I think it might have manifested via the DTC codes read by the COMBI from a bit that indicated rather generically either Fuel Pressure Low or Oil Pressure Low. That's at least my best guess.

In several years of viewing submissions of S70/V70/C70/XC70 scans at kwpd3b0_interpreter.html, I **never** once saw one that Low Pressure flag indicated. Also, in the several years I had a 98 S70, I never encountered that flag set.

So I think the 96/97 850 (and possibly 98 S70/V70) have the Low Oil Pressure detection capability that manifests as a DTC error seen by the COMBI ECU, but it's very rare, and it's essentially moot, since it probably kicks in just before the engine is about to go kaput. Hopefully, some other DTC error detected by the Engine ECU -- as previously mentioned in this thread -- gives a more timely clue that something was awry, long before there is engine damage.

3. Bottom line:
- Check your oil level at appropriate intervals for your car.
- Don't depend on the 850/S70/V70 to tell you the oil level is low.

esl_97_850_T5

[Goupil]

Can confirm that 98 S/V/C70 (turbos at least) have the oil pressure switch at the front of the block, this one
https://www.skandix.de/en/spare-parts/e ... h/1004997/

[abscate]

That’s the only oil pressure switch on white blocks. It is not a pressure sensor,it’s a pressure operated switch that opens at oil pressure above a nominal, low value.

The ECU cannot report oil pressure as it isn’t measured directly on these cars

For completeness…

The oil pressure switch is located on the front of the cylinder block and consists of a switch which closes when oil pressure in the engine falls below 40-60 kPa (5.8-8.6 psi ). When this circuit is closed an output in the combined instrument panel is grounded and the warning lamp lights.