I previously reported a problem with my ignition light staying on.
Lots of suggestions and lots of trying different angles.
Still trying to get it to go off when the engine starts.
Took the alternator off and sent it to an auto electrician who rebuilt it.
Changed the can, the voltage regulator, checked the wiring.
The battery was on the way out so changed that, but still the light stays on…
Then today I did something stupid…
I started the car and she was running nicely. As I have the dash top off I was trying the connections to the ignition light and I touched the body. A spark. The engine died and wont start.
Lights and everything else work, but the engine is dead. WTF have I done and how do I fix it…
Does the engine crank and not fire, or doesn’t crank?
If you were messing around with the ignition lamp with the ignition on, the White wire on that lamp would be live and unfused. So if you touched it to ground there would be a spark and if you left it touching for long enough something would have melted and burned. I would start by diagnosing what “White wire” circuits no longer work. Some easy ones are (a) does your fuel pump still click when you turn on the ignition? (b) does your handbrake/brake fluid level light come on when the handbrake is on with the ignition switched on. If there is no sign of life on these two circuits it suggests that the ignition switch or the cable from it to the fuses took a hit.
Another approach is to get a voltmeter and check voltage at the coil (which likely there is none) and then work back through the schematic checking for voltage.
I am not sure what year your car is, so the ignition wire might go through the tachometer. If so, you may find out you pulled the wire off the tach while working in that area with the dash top off.
I checked and followed everything and l found an in line fuse that wasn’t there when the car was built……
I checked it and it had blown, changed it and everything back to normal?..…
The ignition light is not lit now at any time, so it might just be the bulb. I need to get a spare one anyway. I haven’t yet checked to see if there is power to the bulb holder, but l will.
Had enough for one day.
Engine starts. I am happy for today.
I will let you know what l find…
3AW controls ground, so if you’re confident that it’s new and working, there has to be a short to ground either at the bulb socket or in the wiring between the bulb and 3AW. I would take the socket out and inspect it closely.
I have put on a new bulb holder and a new 3AW and have power to the ignition light socket.
I was thinking of running a temporary wire from the earth lead on the ignition light bulb holder to the 3AW to see if that worked.
I thought that would show if there was a short on the ignition light earth
Which terminal should l connect the earth to on the 3AW. The yellow, the brown and black or the black?
Be sure to take fuses out n check them and across the terminals. I thought a number 3 fuse looked fine but it wasnt fully in the slot, and one time looked good n number 6 was blown. Relays, you need to get the schematic n short the leads properly to see if bad. What series you have? Lots of schematics online.
A question
If l check the ignition light earth with a temporary lead to the the 3AW and the light stays on, could it be the alternator relay?.
If so which of the two relays beside the battery is it… The top one or the bottom one?
The alternator has been rebuilt and is tested between the battery and the alternator at between 13- 15 amps when running. It is a brand new battery. I fitted a new 3AW and a new bulb holder.
Running out of ideas…….
If it’s a 68 it’s a series 1, tho most use the term 1 1/2. Many improvements. Show a pic of headlights, taillights n hood (bonnet)front scoop . What does the Jaguar Certificate call it?
As there was not a Series 1 1/2 officially recognised by Jaguar it would have to be either a Series 1 or Series 2.
It came off the line after October 1968, so is listed as a Series 2 i.e. without the headlight covers, toggle switches and larger air intake on the bonnet, (hood you call it…) The rear end is also pure Series 2.
Ok, let’s cut to the chase. The 3AW circuit is independent of almost everything else in the electrical system. It does depend on the AL tab of the alternator, so you should check that and make sure it’s getting between 7-9 Volts on the AC (not DC) scale of your multimeter. The other two wires are a ground, which you can check in the usual way you check grounds. And finally, the low side wire coming from the bulb. Your system seems to be somewhat munged, and I guess they added an inline fuse, so check that. None of the other fuses are relevant.
If your voltmeter shows a charge, then your alternator relay is fine. If your AL tab shows 7-9 VAC, your alternator is fine. All that’s left is a ground and the wire coming from the bulb. Turn the key on and ground the bulb wire to any convenient chassis part. The bulb should come on, remove it from ground and the bulb should go out. If the bulb doesn’t go out, then there’s a short in the socket or wiring. Otherwise, if the ground checks, the 3AW is fershitzen. Whose 3AW did you install? I’m not sure who supplies one with black, yellow and brown wires.
Puleeze don’t get into a pedantic argument over what constitutes a series 2, it won’t help you find the problem.
If the Serial Number of the car is 1Rxxxxxx or 2Rxxxxx it’s a Series 2. If the Serial Number is 1Exxxxx it’s a 4.2 Series 1 (or 1.25 or 1.5 if you acknowledge fractional Series Numbers). It’s simple - no arguments - end of story…
The brown and black wire is the wiring ‘To’ the can.
The wiring colours from the loom are brown and black, yellow, black
They fit to the 3AW via the spade sockets. The new one was bought from SNG and is identical to the original
The yellow wire is the AL wire coming from the alternator. It should have 7-9 VAC when the alternator is running, measure against any ground with a multimeter set to the AC scale.
The brown/black is coming from the bulb, it’s the low side (WL). If you ground it with the ignition key on, the bulb will light. If it’s ungrounded, the bulb would be off. If it stays on either way, the most likely problem is that the socket is shorted.
The solid black is your ground (E), you can simply measure resistance to the battery negative with your multimeter set to the ohm scale.
If all three wires check, the 3AW is either bad, or you’ve confused the contacts.
