Skizzer's XJ-S

[wuvvum]

The boot lid on mine was a twat for not staying closed.

[dollywobbler]

The ventilation on 'mine' is hopeless. It's a bloody odd system. I suspect mine is out of gas too. 

 

I love the tow bar on yours though. Imagine the MPG when towing! We must get the two together at some point, before mine is reclaimed.

[Skizzer]

Makes me chuckle that so many of us on here have / had / are running around in someone else's XJS. Gotta love a big old Jag.

 

I'm game for a trip up your way DW - should be free from work after the 21st, or if that's too late could try and squeeze in a weekend day. I have a new filming gadget too, as threatened a while back.

[Guest Hooli]

Looks bloody wonderful, I'd love an XJ-S.

[Skizzer]

Jag still FTPing, even after charging the battery. Suspicion now passes to the starter motor - all click and no whirr.

Shame I'm missing the sunshine* - I'm sure* there's room for one more under that gazebo.

So after the Jaguar's non-appearance at Shitefest, I cleaned up all the contacts attaching to the starter relay inside the front wing and joy! Power was restored to the starter motor.

 

But not to the plugs. Bugger.

 

Just as well it's not the starter motor itself, because I still can't find it. It's buried in there somewhere: at least now I can hear it so I know it hasn't fallen off.

 

That was yesterday, and it's been pissing down most of today so I haven't got any further. Maybe tomorrow a miracle will happen and I'll find what's wrong. The coil is where I plan to look next, because I think I've found that.

 

 

Edit: oh and needless to say, this process involved shearing off a captive bolt from the bracket the relay hangs off, so I had to faff around drilling that out and replacing it with a stainless steel nut and bolt. Why does every job spawn three more?

[xtriple]

Starter motor removal requires you buy about 6 socket sets so you can get all the extensions together that you need, then take the bonnet off and feed all the extensions with socket on through all the pipes and exhausts and onto the nuts. It is a 'real fun job'.

 

I had a mystery electrical fault on one of mine which turned out to be on the drivers side of the bulkhead there's a connection for the main power lead and it had become dirty.

[Skizzer]

Starter motor removal requires you buy about 6 socket sets so you can get all the extensions together that you need, then take the bonnet off and feed all the extensions with socket on through all the pipes and exhausts and onto the nuts. It is a 'real fun job'.

 

I had a mystery electrical fault on one of mine which turned out to be on the drivers side of the bulkhead there's a connection for the main power lead and it had become dirty.

 

I know I'm not the most skilled at this sort of thing, but I genuinely can't see anything that looks like a starter motor, at least not without removing an exhaust manifold.  Maybe it's visible from underneath.  Anyway, luckily that doesn't seem to be the problem (this time).

 

I've heard others talk darkly too of this connector you mention, and it seems to be a favourite point of failure.  I shall track it to its lair and zap it with my trusty contact cleaner / emery paper combo - when this rain stops.

[xtriple]

From (failing) memory, the starter is on the drivers side at the back (well, there's a surprise!) and is a biatch to get at. There is a recommended way but I cant recall what it is, but long winded and costly. If you go through from the front with extensions and u/j s you 'can' get at the three bolts and it comes out underneath. Not a fun job...

 

The electrical connector is one of the few easy things to check/get at as it is just below bonnet height and about 8 inches in from drivers side wing. The one I had that failed used to pretend it was a car from 'back to the future' as it would start to turn over and then just fade away... I love the noise that the V12 Jaguars make on the starter!

[Bear]

When I first started mine after bringing it up on the trailer, it made a whirr and sounded like starting some sort of plane.

 

With a conditioned battery, it starts so quickly you don't really get to enjoy any starter noise. It's like "click - running".

[Skizzer]

I can't believe all of July and half of August has gone by and this is STILL sitting broken outside my house.

 

To recap: the starter motor turns, but there's no spark according to my light-up spark plug telltales (which work on other cars).

 

I've replaced the ignition coil. That didn't help. There's still no spark.

 

I made myself a simple continuity tester out of some wire, a crocodile clip, an LED, a resistor and a ballpoint pen. Here it is in action:

 

 

The positive end is clamped to the battery's positive terminal; the negative end is fixed to the positive side of the coil. It lights up when the key is out of the ignition or in position zero. The LED goes out when you turn the key to start the car. Isn't this the opposite of what you expect?

 

Any ideas? Help!

[Skizzer]

Oh, and it's not my continuity tester that's weird - it works fine just across the battery terminals by the way.

 

I'm quite proud of my little homebrew tester in fact, it's got proper soldering in it and everything. Just a pity the picture is sideways.

[The Reverend Bluejeans]

The XJS problem solver.

[Skizzer]

Thanks, I'll bear that in mind.

[Magnificent Rustbucket]

Crank position sensor?

[Junkman]

Does that thing have some traces of an immobiliser left?

[Magnificent Rustbucket]

When the engine turns over trying to start, does the rev counter register any revs? On earlier XJ40s, one of the ways to diagnose a failed CPS is that the rev counter does not move up when the engine is cranked. The XJ-S V12 may be the same.

[D Spares & Tyres]

ECU? These have been the cause of problems on two I have worked on  although it affected the fuel pump rather than the spark

 

Is or has it been damp? 

[Skizzer]

Does that thing have some traces of an immobiliser left?

Christ, I hope not, scary thought. I don't think so, the keys are the usual BL mish-mash that look like they fit Goldilocks' and the Three Bears' bicycle padlocks. No sign of any electronic wickedness.

 

I hope it's not the crank position sensor, I bet that's a day's work to find. Would that isolate the coil?

[Skizzer]

ECU? These have been the cause of problems on two I have worked on  although it affected the fuel pump rather than the spark

 

Is or has it been damp?

 

We did get some epic rain, so I guess that's possible. I wasn't driving in it though, it was just parked - I hope it's not that sensitive to weather or we're not going to be friends for long.

[Skizzer]

When the engine turns over trying to start, does the rev counter register any revs? On earlier XJ40s, one of the ways to diagnose a failed CPS is that the rev counter does not move up when the engine is cranked. The XJ-S V12 may be the same.

Good question, I'll look in the morning if I have time.

[D Spares & Tyres]

We did get some epic rain, so I guess that's possible. I wasn't driving in it though, it was just parked - I hope it's not that sensitive to weather or we're not going to be friends for long.

Water leaks in through the boot. Then evaporates and collects on the ECU....... 

[Bear]

Daft question

 

Is the ignition switch okay? Could turning it to starter break the ignition circuit?

[anonymous user]

I'm not sure if I have the wrong end of the stick, but if you have one end on the positive at the battery and it is lit when you touch the positive side of the coil that would indicate that it is earthing out. If it then goes out when you turn the ignition on that would be the positive supply getting to the terminal therefore two positives and no circuit. Of course if your one end is on the earth and the other on the positive at the coil you should only get a circuit when the ignition is on.

Is the coil dodgy?

I did fit a new coil to one of the Volvos it lasted nearly half a mile before failing luckily I had the old one with me

[Pillock]

That's what I thought when I read what you'd done with your homebrew tester.

 

One end positive terminal of battery, one end positive terminal of coil, battery is always live but coil is only live when ignition on.

Ignition on, no potential difference.

Ignition off, you've got 12v difference so current flows.

 

You need to swap one end to a negative thing. And it matters which end as it's an LED so try it both ways

[Skizzer]

Boot is dry, so I don't think that's the prime suspect. Ignition switch is a maybe though - I still think that behaviour with the circuit tester sounds weird.

 

You'll recall that the first FTP had the starter not turning - which I fixed by cleaning up the contacts on the starter relay. This relay has about 8 contacts, only five of which are used. One of them runs to the coil, so maybe that relay is buggered?

 

Edit: scrap that, just read Anon and Pillock's posts which of course make sense - I fail at car wiring.

 

Back to the drawing board with the diagnostics.

[Asimo]

Lots about the various V12 Jaguar electronic ignition systems here:  http://www.jagweb.com/aj6eng/ignition.php

 

First off, find out which system your car is fitted with. As the piece says at the end, you may need a guy with an oscilloscope. Without you are working blind really.

[Skizzer]

Ah. That's a very informative article, thanks, but as soon as you said oscilloscope I started to visualise a ride on the back of a truck in the XJ-S's immediate future.

 

As a man who can't figure out which battery terminal to attach a circuit tester to, I rate my chances of debugging an electronic ignition module at awfully close to zero.

[kinkersaab]

My v12 has a wee cut of trip thing on the side panel near where your right knee is when sat in drivers seat..it skinda burried away. It has a platic peg thing on the top that needs to be pulled up for car to start. I was in another v12 a few weeks ago and it had the same contraption...worth a look

[Junkman]

Could it be that the ignition switch is buggered?

[Dippy]

I love these cars and did consider buying one a while back but the thought of constant problems I couldn't fix myself kept me at bay.

I like to be able to fix everything myself so keep to much more simple cars, sorry this doesn't help,with your problem but great to see somebody having the balls to run these especially in V12 version.