XJ6 & XJ12 Series I, II & III 1968-1992

Ignition Light Remains On

 
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Old 07-03-2019, 10:05 AM
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Default Ignition Light Remains On

Hi. I apologize in advance for the long post, but I want to provide as much information as possible for anyone who might have an answer. I recently finished some work on my 87 Sovereign during which the front end was jacked up with the tires just a few inches off the ground for two weeks and during which I did not run the car. Prior to this the car was running fine and the ignition light was off. After I finished the work I let the car down and let it sit for several hours for all the fluids to level out (even though the front end was not elevated very much during the work). The first time I started the car up after this the ignition light remained on and has remained on when the car is running ever since. I have driven the car on short low rpm drives and extended highway driving since. The car starts, runs, and performs perfectly. Voltage is pegged at 13, oil pressure and temperature are at 4 and just below the green respectively. All electronic systems function as normal.

The only electrical things I did when working on the car was trying to trouble shoot the washer pumps (it's a Sovereign, I have two, one for the outboard headlights and one for the windscreen both attached to the back of the reservoir). After I had removed and cleaned the washer reservoir and reinstalled it the windscreen washer did not work but the headlamp ones did. The power for the two pumps runs from a wiring harness that branches into two and connects to each of the pumps. I tested both pumps (they both work) and determined that I was not getting power out of one of the two connectors. I then cleaned all the connector contacts and tested the plug they connect to (see picture) and determined that I was only getting power from one of the two poles. I did not trace the problem further. I then reconnected the harness, attaching the working connector to the windscreen pump and the non-working connector to the headlamp pump (which may have always been the case I do not recall verifying that the light washer worked but the windscreen one always has). While trouble shooting this I turned the key to the number 2 setting (since the car was jacked up I didn't want to start it) for a few seconds at a time to test the washers with the switch on the stalk. I have a battery isolation switch, but I did not always turn it off between tests. I was carefully not to short anything out with the tester.

The only other systems that were in anyway manipulated during the work was that I removed what I believe to be the coolant expansion tank mounted on the driver's side (left) wheel well which did not seem to be in anyway pressurized (so I didn't think removing it would be a problem). On the passenger side (right) I unbolted what I believe is the charcoal canister from the support strut but did not disconnect anything. However, a small hose that was attached to a nozzle on the canister did come free of its own accord during the work and I simply stuck it back on to its nozzle again. It was not held by a clamp or anything and again, this system did not appear to be pressurized. I replaced all these parts as I found them. After running the car I checked to make sure the small hose was still attached to the canister and it was.

So, my questions are:

1. Generally speaking, when the ignition light stays lit, what CAN it signify?

2. Under the circumstances described above, in my case what MIGHT it signify?

Given that the car is running fine in every way, my optimistic assumption is that whatever is causing it is minor.



Connector for washer pumps (foreground)
 
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Old 07-03-2019, 11:32 AM
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Assuming your car is a SERIES 3. either the battery or the alternator.

Try disconnecting both cables at the battery and reconnecting them.

Try pulling and pushing the connectors behind the alternator.

raising the front of the car or messing with the washer wiring would not cause an alternator/battery light to come on, neither would keeping the ignition switch in the accessory position, ( other than discharging the battery if using the radio for a long time, or keeping doors open with interior lights on).

since you have confessed to keeping the ignition switch on, you might have discharged the battery some.
 

Last edited by Jose; 07-03-2019 at 11:35 AM.
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Old 07-03-2019, 12:07 PM
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Thanks. I thought I might have run the battery down which is why I ran it on the highway a good long while to see if that was the problem. If it was the alternator I would think the battery would be discharging and this would show up on the voltmeter. But I will certainly try both your suggestions.
 
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Old 07-03-2019, 12:12 PM
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The ignition light on usually signifies no charge from the alternator, the ignition light requires voltage to extinguish it so check wiring on the rear of the alternator hasn't been disturbed or the connection isn't high resistance with corrosion. The battery is big enough to provide power to start and run the car for some time. Failing finding any problems with these checks remove the alternator and get it checked out at a local auto electrical workshop.
 
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Old 07-03-2019, 01:29 PM
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Thanks. I’m finding accessing the back of the alternator from above to check the wires to be tricky because of the ac compressor.
 
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Old 07-03-2019, 01:34 PM
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You mentioned that the voltage is right at 13v. Is that with the dashboard volt guage or a multimeter? Turn the car off and use a multimeter between the poitive and negative battery terminals. A good battery should read 12.5v or a little more with everything off. Start the car and do the same check. With the engine running you should see over 13v if the battery is fully charged. If the battery is run down or old or failing you will see voltage as high as 18v. If the reading is the same running and off the battery is not getting juice. Alternator or wiring problem.

Dashboard gauges are not very accurate. I would guess the experts above are right and it is a loose or corroded connection somewhere.

Jeff
 
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Old 07-03-2019, 01:47 PM
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Yes that is off the dash gauge. So if the alternator is working properly with the engine running what should my voltmeter read when I test the battery? 13? And I’m sure it’s a stupid question but why does the voltage read higher if the battery is not charging? Thanks.
 
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Old 07-03-2019, 02:40 PM
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Just checked with the multimeter. 12.65 volts off. 14.25 volts engine running. I don’t know what my baseline was before the light went on since I never tested it. Is14.25 within the range of normal or does it indicate the battery is discharging?
 
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Old 07-03-2019, 03:05 PM
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Have you checked the "exciter" wire (narrow gauge wire) at the back of the alternato? These become dislodged quite easily and if so, that warning light will illuminate.
 
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Old 07-03-2019, 03:07 PM
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From those readings it looks like the alternator is charging okay so concentrate on the warning light circuit. A high voltage reading is usually caused by a bad connection to the battery from the alternator or a cell shorting out causing the remaining ones to be over charged.
 
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Old 07-03-2019, 03:12 PM
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Those readings sound good to me. I would check the indicator light circuit.
 
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Old 07-03-2019, 03:15 PM
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Thanks for all the advice. I’ll focus on the alternator wiring first. I remain optimistic that it’s a warning light issue rather than an alternator issue but on the other hand I know next to nothing!
 
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Old 07-03-2019, 05:41 PM
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Here is the schematic for the light. The wire (NB) is brown with a black tracer.


 
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Old 07-03-2019, 06:44 PM
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Thanks. I’m new to reading schematics (stupid humanities degree!). So that wire should come right off the back of the alternator is that correct?
 
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Old 07-03-2019, 06:49 PM
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I never believe dashboard volt meters.
They're only a rough guide if the system is charging or not and a very Poor indication of how much actual charging there is.

Mostly, they make the driver feel good about having a meter, and are a selling point for the manufacturer.
Oh. And they look nice on the instrument panel.
(';')
 
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Old 07-03-2019, 11:30 PM
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Originally Posted by Gismo View Post
Thanks. I’m new to reading schematics (stupid humanities degree!). So that wire should come right off the back of the alternator is that correct?
Yes, as I said above (#9) this wire comes right off a connection (spade connection as I recall) on the alternator.
 
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Old 07-04-2019, 10:39 AM
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True, the instrument on the fascia is an "indicator" not a guage in the true sense. I use mine as a guide. As long as it is at 13v or close, I am confident that all is well.

I made a patch cord for my VOM. Plugged in to the cigar outlet, it is really interesting. real voltage in real time at various rpm's and loads. I thought I was a genius for coming up with the idea. Wrong, similar plug in devices are on the market !!!

It has been a long time since I had a car with an ammeter. I liked those. fire the engine and see the meter swing to charge. Add load and watch it back down.

Really old USA critters did not have an accessory position on the ignition switch. So, enterprising young men found a way to park with a best girl in a secluded , but scenic spot. bump the starter carefully, not start, but just enough for the ammeter to show no discharge. Signifies ignition points open. Not being burnt out and the resultant no start!! Now, radio on, romantic tune, romantic mood... Those wuz the days.


Yup. two wires at the alternator. Small one to ignition light. large one to the post on the fire wall just by the battery... Each need to be clean, tight and lubed... Jaguar mantra...

So far my car's hissy fits have not returned. New coil wire and another coil/module. the "old" coil wire was loose and corroded. Replaced by anew wire. so, was t the coil/module as well as the clearly bad old wire? Original mdule placed in "reserve" but labeled, "may not be good".

Daughter comes later with lunch. Yum... .

Carl

 

Last edited by JagCad; 07-04-2019 at 11:14 AM. Reason: tyo correction and information
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Old 07-04-2019, 12:18 PM
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Thanks for the memories Carl! I’m good with my hands but carpentry is my thing and I don’t have the same facility with mechanicals and metal. So my first jaguar is also the first car I’ve worked on (other than changing oil or spark plugs). Before I started wiggling wires I wanted to be sure which one I should focus on as every time I fix something I seem to screw up something else!
 
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Old 07-04-2019, 01:57 PM
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well, onloy some of us that enjoy old cars including Jaguars have technical degrees. My degree is in History with the minor in government. Aimed at possibly law. It did not quite work out that way! But my career in insurance claims came close.

I did get some technical by my work during my college years at a full service station. We did a lot, including light mechanical. Leaned much there from skilled guys that were willing to mentor me.

Carpentry!! I like to make saw dust as well. Far from skilled. But, I have a lot of tools. Band saw, contractor's saw, chop saw, drill press, plus bunch of motor driven sanders, saws, etc.

At present, I am messing with my Delta knock off band saw. Getting the guides and tension just right so it doesn't toss a blade. One of the guides, under the table, of course, has a missing Allen grub screw. Can't seem to find one in my trays that fits. Using my best glasses and a powerful "torch" I've concluded that the threads are stripped!!! Not by me. I've not touched that one.
But, I think I got the "little" blocks in line with the blade!!! Next up, try it ands if it works, replace the upper and lower covers. Care of course running sans covers!!! stand aside!!!

That schematic is really great. for example the "NB" along the ire describes it's color. The first pages of the booklet describe the color codes. It also identifies the symbols, switch,,connector, etc. I've used it a lot and learned a lot. by far the best schematic I've seen in decades.

Just noted on my car that I have a bulb out. Warning light on the fascia. Son was by. Checked rear lamps. All OK except left brake light. Next day or so, i'lll unlimber my electrics, select the proper Pozi drive, Idf the bulb and I may have a replacement in my bins.. In jaguar electrics, the brake lights do not work unless the ignition ids "on"!! Learned that the "hard way" a couple of years ago. Fixed twice. one bodge, then the right way.

Perusing that booklet will teach you a lot...
Carl .
 
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Old 07-04-2019, 03:03 PM
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Thanks Carl. Where can I get the schematic booklet? I’ve got the Haynes.
 

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