[xj] Oil pressure warning light failure

Good evening everybody,

recently I realized that my red oil pressure warning light
didn’t light up when starting the car. The oil pressure
guage shows sufficient oil pressure, so I’m quite relaxed.
Yet, I intend to rectify this issue.

Yesterday I swapped the oil pressure warning light bulb in
the warning light cluster (simply pull out sharply) with the
functioning handbrake warning light bulb, unfortunately to
no avail.

So either the sender is shot or the electrical connection on
its way to the warning light cluster. Is there any simple
procedure to rule out the electric alternative? Will the
light come on when I put 12 V on the sender side or when I
ground the sender side?

Thanks in advance

Jochen–
75 XJ6L fern grey auto
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In reply to a message from Luft-Schiff sent Sun 28 Feb 2016:

Light should come on when you ground the sender wire, Jochen.

Also, the sender should read a short circuit to ground with
an ohmmeter when the engine is not running, and should go
open circuit (infinite ohms) with the engine running.

The other (non-sender) side of the light should receive 12V
with ignition on, engine running or not.–
The original message included these comments:

procedure to rule out the electric alternative? Will the
light come on when I put 12 V on the sender side or when I
ground the sender side?


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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The archives and FAQ will answer many queries on the XJ series…
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Thanks Bob!

that’ll help me out. I’ll check voltage at the light bulb first, then
access the sender … who knows - maybe the wire at the sender has just
fallen off.

All the best

Jochen>

Date: Sun, 28 Feb 2016 14:30:38 -0800
From: “Robert Wilkinson” wilk@wustl.edu
Subject: Re: [xj] Oil pressure warning light failure

In reply to a message from Luft-Schiff sent Sun 28 Feb 2016:

Light should come on when you ground the sender wire, Jochen.

Also, the sender should read a short circuit to ground with
an ohmmeter when the engine is not running, and should go
open circuit (infinite ohms) with the engine running.

The other (non-sender) side of the light should receive 12V
with ignition on, engine running or not.


The original message included these comments:

procedure to rule out the electric alternative? Will the
light come on when I put 12 V on the sender side or when I
ground the sender side?


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

To remove yourself from this list, go to http://www.jag-lovers.org/cgi-bin/majordomo.

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Hi Jochen,

have you find the cause for that? I have exactly the same case…except that it started after part of the engine, where oil warning switch is, was flooded with coolant fluid. I cleaned the connector to that waring switch but still does not work…not sure what are the chances that switch is actually broken?

Have you found why warning light does not work?

Thanks, Cene

Being repiticious.

Volts to the bulb. Light up?
Ground at the sender. Lamp on?

Aye, the senders are not all that robust. Mine went bonkers. replaced. tossed the old one so as not to confuse me or anyone else in the future,

A learning moment!!! Purpose. Light the oil lamp warning of low or no oil pressure. How does it function. A switch. Open when pressure present. Closed as OP presents itself. Switch function. Opens and closes the circuit on the ground leg…

Test"

Apply volts. Or supply a ground

Were I to mess with my car’s electrics, I’d invest in a voltage probes/

But, now, I gotta probe test some house fuses… Lost a circuit. Got carried away, too many eectric gadgets on one circuit.

Carl

Hi Carl,

thanks for your advice… yeah, volts are on the warning bulb holder. Did not yet try to connect ground to switch cable, will do tomorrow, I guess. I must connect cable to engine, right - and the warning light should work - that would mean the oil switch is broken. Correct?

I just hope it is the oil switch and not some hard to find connections between switch and dashboard… Thanks for info on those switches, I thought they never fail…but probably they donˋt like to be flooded with hot coolant, right?

Cheers, Cene

I’d touch the wire spade connector to the engine. If the light doesn’t light, scrape the female spade a bit on the engine, or a fastener, to ensure a good ground. If it lights, try scraping it on the sensor spead to ensure a good connection; the antifreeze might have “insulated” this connection. Assuming it lights when grounded but not when attached to the sensor it’s definitely the sensor (or, very unlikely) it’s threads are insulated from the 1/8 BSPT tapped hole in the engine.

Or remove c the switch/sensor and test it for continuity with a test lamp or VOM.

Just did on a batch of house glass fuses. One of four is open!!! Tossed. Now to gues swap in til the lamp lights!!!

Carl

Sorry Cene,

for not having closed the thread.

At the time I checked the circuit as described and found the sender was the culprit. I fitted a new sender - not very expensive - and have enjoyed a functioning (though almost invisible in the warning light cluster) oil pressure warning light ever since.

The only problem then was that it was quite a job to pull the defective sender.

Good luck with yours

Jochen

75 XJ6L 4.2 auto (UK spec)

Thanks, Robert! I managed to pull the connector from the switch with long pliers and cleaned the male part of the switch with toothbrush soaked with contact spray…but could not do the same with female connector of the wire…all is damn deep and hard to reach…will try again and do exactly as you wrote, tomorrow.

Thanks a lot,

Cene

:grinning::grinning::+1:t2::+1:t2::+1:t2::+1:t2::+1:t2::+1:t2:

Cheers!

I take that as you win!!!

Kudos…

Carl

Hi Jochen,

thanks for your info. Yeah, I hope in my case it is the same… I have already ordered new switch, an hour ago… will see.

Best, Cene

Guys, just checked ground to wire and warning light works…so it must be the switch. Thank you all for your advice and help.

Cheers, Cene

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