Hello my name is Rene Im new to the forum but long time lurker and this is by far the best jaguar site for information on problems with these puppies (Jaguars). I have a 1998 xj8L and for a while i would have a problem with starting the car up. I would crank it up and nothing would work no lights, no spark, nothing........then i would go and move the batery a little and mess with the ground cable (im not to mecanically inclined but its the cable that goes from battery to chasi i believe) and the lights would come on and car would start. I got a new ground cable cause it was a little brittled but problem still persist and since everytime it would do this i would go back there move the battery a little or mess with the cable and everything would lit up and car would start. Now, i have a problem that when I go start the car everything lights up but now car wont start. No spark, no crank, NOTHING.....mess with the battery and the cable but nothing. Everything lights up but no crank and no spark........when i turn the key all i hear is like a click like 1 second after i turn the key.......car has been in the shop for about 3 days and cant figure out what it is.......battery is good.......they even try to bypass it to see if it cranks but it tries to start but it wont. Can someone shed some light on what it could be........or what i can check for the problem. Thanks

 

Check the false bulkhead stud electrical connector under the bonnet-it carries the main high current for the starter motor & also the charging current from the alternator.

To find it, open the bonnet & look at the back of the engine bay by the windscreen-you'll see a central long plastic trim piece & also 2 large plastic corner-shaped trim piece covers on each side of the engine bay by the rear of the front wings

If you look at the RH corner top plastic trim cover (passenger side on US cars), you'll see a large rubber cover & a thick lead coming out of the front of the casing piece below the plastic cover. This is the rubber cover for the false bulkhead connector-pull this cover back & check the condition of the electrical connector behind it, as well as the tightness of the connection.

It's very common for this connector to corrode or work loose-it carries the main starting current & alternator charging current for the car, so is very important for correct vehicle electrical system operation. See this thread for more info & pictures:

https://www.jaguarforums.com/forum/x...nnector-92454/

Also check the ground strap from the engine to the chassis as this will cause similar problems.

 

This is what the false bulkhead connector looks like:









Make sure the nuts are all tight & that there is no corrosion on the connector, as it supplies the high current to the starter motor & the charging current from the alternator to the battery.

 

I agree with the previous post. This is almost certain to be a bad ground problem, and as the XJ's use multiple grounds do yourself a favor and check ALL OF THEM while you're at it. Also get your mechanic to put a load tester on the main feed to the starter and see how high the current draw is. It's possible that with the poor electrical connections you've been experiencing for awhile that the starter is going (not too likely) or that the main running to the starter has gotten too high a resistance through age and internal corrosion.

Check those grounds and bet sure they put a real load test on your battery. Heavy amps and then check the batteries recovery time.

 

Also, in the trunk are a couple of VERY LARGE fuses. They bolt up against the front side of the Spare Tire well inside a black box about 5 inches square. Those connections can also become loose.

I don't have my XJR anymore, but they are located beneath this cover about where I've circled.

 

ok guys thank for the feed back i will relay the message to mechanic and ill post back result.........thanks again

 

Just a thought.... have you tried powering the engine from the power point under the bonnet at the side of the fuse boxes? This will eliminate all the earthing points and prove if it's the earth or an engine problem. The positive terminal connects to the shrouded connector between the fuse boxes then it's just a matter of making a good earth. This is also the point to use when the battery is run-down and you can't open the trunk or as I did once, removed the battery for charging and closed the trunk!

 

Thanks guys again for feedback mechanic came said their is no juice coming out the ECM to starter he said best bet to have them reprogrammed to the keys and go from there.....could that be the culprit......having it towed to the dealer soon.....they'll do it for 150 ............I did have 2 computers so when this happened I switch them thinking that was the problem and mechanic said that could send the system out of whack......I'm no way mechanically inclined would this be accurate.......thanks

 

Didn't see that post before I will try it and get back but I'll check it out

 

Mmmorri they tried that and it turns over but doesn't start"........if you r telling me to bypass to get it started that's what happened it now has a spark but don't start

 

If there's spark getting to the plugs and it won't start then you should also look at the air supply and obviously the fuel delivery system. Spark + air + fuel = bang ! spark +air - fuel = hot air, like many so-called mechanics.

 

By all accounts it was a bypass to starter only to check power. No spark or fuel would be expected.

 

According to the workshop manual the tech is correct. Almost every module must be programed to correctly interact with the others in the system. That doesn't mean the one you bought as a BACK-UP is worthless, it just would need proper programming to work correctly.

These systems are highly integrated and the failure of one might very well cause a cascade effect that cripples the entire chain. I'm sure there are some failsafe modes but not every possible fault will have a built in safety.

In your case the problem was building over time and in that sense was trying to warn you of bigger problems ahead. Possible ground problem or weak battery/charging system might have been the root cause or one of the more important modules was starting to go bad or get corrupted data. It might be that your just fooling around with the battery and cables each time was enough of a power surge (on/off if you will) to further scramble the ECM's brain. With computers they will sometimes, even though heavily fortified against it, be brought low by even the slightest of surges if repeated often enough.

We once had a small mainframe burn out due to the power fluctuations from the grid as a voltage recorder showed us how much variance there was in line voltage from a low of about 114-115 volts to a high of 127-128 volts in a nominal 120 volt circuit. Before we installed a second unit we got a line conditioner to even out the spikes.

A home fixit note. If you really want to have long life bulbs in your house search for commercial grade 125-130 volt rated bulbs. They'll not shine quite as brightly at the lower 115-120 of normal household current but they easily take the abuse of the normal surges that go with the power company brownouts. My late father-in-law had one on his back porch that was still going some 15+ years later at two different houses !!!

 

But PLUM he stated that he now has spark so something doesn't jibe. Of course fuel flow is probably also controlled by either the ECM or another interrelated module so around and around we go.

Not only are we trying to help diagnose a problem without our hands (and eyes) on, but we're trying to do it without ant equipment to test our hypothesis. A daunting task at best and we can only hope that we may provide a hint that proves out.

 

For all we know "spark" could have referred to a spark at a power cable. It took a good long time for the info that foreign modules are involved to finally leak out.

BTW, around here some places sell "rural" bulbs. Sure enough ... 125-130 volts on the label. Still waiting for LED bulbs to come down in price.

 

On the right side of the car for US units behind the firewall there is a reset button for the fuel system. My guess is that the mechanic opened the fuel line at some point caused the fuel system to shut off the system; it is designed to protect the car in case of fire or an accident.

Spelling punctuation grammar and capitalization errors are Siri's fault sent from my iPad

 

The original fault was intermittent starting that then became a permanent non-starter. The O/P noticed that moving cables would sometimes cure the fault, so I think the first thing to do is check over the main electrical connections across the vehicle.

Jump starting the vehicle from the point between the 2 engine bay fuse boxes is not advisable, because this supply route has a smaller fuse rating from the battery & when the starter current passes along this new route, it may well blow the smaller fuse in the boot.

I would suggest checking over the mail electrical connectors-I wrote a thread on this recently:

https://www.jaguarforums.com/forum/x...ections-94978/


I would also have the main engine ground strap checked from under the vehicle-any high electrical resistance here will cause starting & charging problems...