I have a continuous oil pressure light on the dash. I've taken continuity readings on the switch and the switch is working and detecting oil pressure. That is pin connectivity to earth when engine not running and open circuit when the engine is running. I now think there could be a short to earth in the wiring between the switch and the instrument unit. Two questions for the gurus out there. 1. Is it most likely to be wiring damage or something more sinister? 2. Wiring diagrams suggest there is an interconnector between the switch and before the instrument unit. Does anyone know where this connector is?
Many thanks
1st Oct 2019 2:28 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Have you tried a physical gauge on the switch port before going any further?
There is a recent post quoting how low the oil pressure is even in a healthy engine and the switch switches at a scarily low pressure.
1st Oct 2019 2:31 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13604
Plus 1, would also be checking the oil pressure is ok, seeing it’s a 2009 ref oil pump cover , better safe than sorry for a 5 x min test
Normal Engine oil pressure:
At idle 0.7 bar (70 kPa) 10 psi
At 3500 rev/min 1.9 bar (190kPa) 27 Psi
These were the figures one of our members tested on his engine
20psi (1.4bar) on idle
and 50psi (3.4bar) when revved.
Thanks for the prompt advice and I'll certainly do a pressure gauge check. One thing perplexes me though, the light's on even when the switch is disconnected - with no continuity with the switch I would have expected the light to go out but it doesn't. (oh and I've replaced the switch with a new one - no change in symptoms and both switch immediately when the engine is started). I'll post my pressure results as soon as I've done the check.
1st Oct 2019 5:29 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10360
From your first post I can understand the engine is fine, and its an electrical issue.
There was another report on this. And I think it was the dash at fault.
I would disconnect the dash connector. and measure continuity between the oil wire and ground.
(should get a short)
then disconnect the oil switch, and it should go open.
If it don't go open, you have a short in the loom.
If it does go open the dash is at fault.
If necessary you could cut the wire a few inches away from the dash plug. to prove.
and/or run a new wire in (if loom fault)
1st Oct 2019 6:03 pm
SomersetTaz
Member Since: 01 Oct 2019
Location: UK
Posts: 19
Thanks Pete,
Is the dash connector easy to get at?
1st Oct 2019 6:22 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10360
its not too difficult.
There is guidance on here and a youtube video (LHD)
I know step 1 is to remove the leatherlike surround around the headlight switch - It pulls off.
&t=5s
TURN YOUR SOUND OFF!
1st Oct 2019 6:34 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
Situated behind the dash which has to come out, lower steering column to max and max out before you start and disconnect battery. No need to take steering wheel off. Column shroud off first.It can when others can't,
It will when others won't,
It goes where others don't.
A quick update - had one more go at the GAP IID to show a friend the issue. The IID recorded a low oil pressure switch and the instrument cluster communication issue. This time after clearing the fault, the dash warning went out (engine running) and hasn't reappeared since. So fingers crossed it was just an intermittent comms glitch. I'll post an update if anything reappears and also the actual oil pressure figures when I get a garage to take readings.
Thanks to all who provided helpful comments.
14th Oct 2019 8:05 am
SomersetTaz
Member Since: 01 Oct 2019
Location: UK
Posts: 19
As promised I have just completed an oil pressure test on my D3. It's mileage is 113,000 miles and has had a recent oil and filter change:
Cold (10 deg C ambient): Initial start up at idle = 50 psi dropping steadily to 27 psi after 2 mins.
Then (after 2 mins at idle) increasing to 3000 revs = 68 psi
Warm (just below midway on temp gauge): Idle = 17 psi and 3500 revs = 55 psi.
This confirms (for the present at least) that the engine oil pressure is within spec.
BTW - after connecting up a trailer the oil pressure warning light is back - argh!!!!!
3rd Nov 2019 12:49 pm
Peron
Member Since: 11 Jul 2020
Location: Kent
Posts: 2
Hi, did you fix this oil light fault as I have the same problem
11th Jul 2020 6:31 pm
SomersetTaz
Member Since: 01 Oct 2019
Location: UK
Posts: 19
Hi Peron,
Not got around to it yet sorry. As a jury rig I connected a hand torch to the oil pressure switch and have the torch switched on before engine start and during journey. (Torch is placed in the door shelf where I can see it.) Light's on before start then goes out immediately so I know the pressure's still good and then I monitor during the drive and when the engine is switched off. I know I'll need to look at the instrument unit soon especially as now my temp gauge has just stopped reading!!!
Regards Taz
13th Jul 2020 8:24 am
SomersetTaz
Member Since: 01 Oct 2019
Location: UK
Posts: 19
Another update:
Instrument cluster out and wiring checked out ok. Plug connector, pins and cluster itself immaculately clean. Before the check I had (as well as the oil pressure warning light permanently on when the ignition is on) I now have no reading on the temperature gauge. IID confirms no problem with temperature and no comms faults relating to the temperature. The IID still registers an oil pressure signal plausibility error.
Not getting anywhere fast any suggestions (other than a match to the car) welcome. Many thanks.
21st Sep 2020 8:16 am
KostasA
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
have you physically measured your oil pressure? if yes maybe try a new switch?
21st Sep 2020 12:44 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10360
Pete K wrote:
From your first post I can understand the engine is fine, and its an electrical issue.
There was another report on this. And I think it was the dash at fault.
I would disconnect the dash connector. and measure continuity between the oil wire and ground.
(should get a short)
then disconnect the oil switch, and it should go open.
If it don't go open, you have a short in the loom.
If it does go open the dash is at fault.
If necessary you could cut the wire a few inches away from the dash plug. to prove.
and/or run a new wire in (if loom fault)
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