AWD Fuel Sender/Level Wiring

befarrer · Post by **befarrer** » 06 Sep 2020, 16:32

Does anybody have a wiring diagram on a V70 AWD fuel sending unit? I have heard they have 2 level senders, and I would like to know how they are wired. I am assuming they are wired in series, so the combined resistance of both of them make up the fuel level. Also, if anybody knows where/if any connections are for the senders, that would help.

Post by **wizechatmgr** » 13 Sep 2020, 21:38

If I remember correctly, they are actually independant and the computer uses an algorithm to determine total tank quantity left. At least on the '99...

befarrer · Post by **befarrer** » 19 Oct 2020, 22:13

Update: We had a 2000 XC70 show up in the auto wreckers, I grabbed both fuel sending units from it. I confirmed by a multimeter, the fuel senders are wired in series, each sender goes from roughly 0 ohms (empty) to 150 ohms (full), for a added resistance of 0 ohms (empty), and 300 ohms (full). There is a plug for the second sender, and if I unplug it to disconnect the left fuel sender, the gauge drops to zero as it breaks the connection. Now that I know how it is wired, I will have to wait until it does not work again to see what is not working correctly, something is shorting to create 0 ohm resisance across a fuel sender. Still leaking on the left one being the issue since the bottom half of the gauge works, and from what I understand, the left tank keeps the right tank full, until it is empty, then the right tank starts dropping.

befarrer · Post by **befarrer** » 27 Nov 2020, 15:00

I finally remembered to check our repair database at work, and they had a wiring diagram, and even resistance values for each sender. I added a screenshot for others to reference. But they do run each sender inline, each sender is about 0-160ohms, full tank is 322ohms combined. But, full tank is 0 ohms, empty is 322. I just filled my tank, and it's reading exactly half. I measured my sender's individually, and the right tank is reading 6 ohms, and the left reads 132 ohms. I doubt a broken wire or anything will cause the exact resistance needed to read an empty tank on one side, so could it be possible my sender float sinks when it's cold, but works when warm? I have noticed when warm, it takes at least 30 minutes before my gauge reads full after a fill-up, yet when I short or unplug my sender, the gauge reacts within seconds. Anyways, looks like my issue is the drivers side sender itself. One day, I'll get around to dropping my subframe to check.