A few nights ago, while driving down the road in my '99 XK8, a traffic light ahead turned red. I like to use the transmission to slow the vehicle before I brake and this time was no exception, except of course for the kitty's reaction. As the gears went to low I heard a loud bang from the rear, the motor went dead and everything electrical in the vehicle went off, lights, radio, everything. Total silence, rolling down a dark highway with no power, worrying the people in the vehicles behind me wouldn't see me before I could coast to the side of the road. OK .. enough of the drama.
Once safely to the side of the road, assessing the situation I noticed the warning beeper that lets one know the transmission selector isn't in Park was still sounding - the bang from the rear end wasn't the battery. I put the transmission in Park, moved the ignition key to full off, crossed my fingers and attempted a restart. Voila! Everything fires up normally and I'm off to home.
I suspect the 'bang' was a backfire as the motor died with fuel in its system. I'm concerned about this phenomena and would like to take steps to prevent it from happening again. I am not sure the transmission downshift was a contributing factor but having the two events occur at the same time should be considered. I haven't seen any posts about something like this but a colleague mentioned something similar happened to him in a Ford Focus (and we all know the shared DNA with Ford).
Thoughts and suggestions from the group????
Thanks in advance,
Beg3Yrs

 

I have heard that the neg. battery cables have been known to fail, causing all kinds of weird things to happen. And when the system goes to 0 volts, all sorts of things are going to go Clunking about.

 

with the ZF5hp24 in your car, I would not EVER use it to slow the car down. The drums inside are prone to failure under normal conditions, let alone non-standard use (like manual downshifting). Unless of course, you've already rebuilt it.

The shutdown doesn't sound good. You still could have damaged a drum (A-drum, maybe B) and it'll show up in upshifting in the future. If it does, any other clunks into gear, or even a restricted performance / gearbox failure, then you'll know what it is.

The only other 'shutdown on the highway' that is often documented, is throttle body or ECM issues...none of which accompanied by a BANG.

keep us updated on anything new!

 

Is the Lucus referal to the old saying of the 60's, "Lucus, Prince of Darkness?"

 

Exactly!

 

Thank you so much for the transmission advice. I don't think it has been rebuilt (third owner at 93K). First owner in CA kept it for 90K and serviced it at a Jag dealer so I've got good records there. Second owner in AZ serviced it at the dealer from whom I purchased the car - no indication of a tranny rebuild there either. So far no indications of any residual problems. If they happen, I hope within the next 20K miles as I purchased a service contract for things like this.

 

This sounds almost exactly like the issue I've experienced twice in 10,000 miles. Did you noticed the headlights flickering prior to the blackout? When it happened to me the "bang" was more of a thunk and it felt like it came from the transmission. Like you, once I turned the engine off and back on again everything went back to normal.

I think it's an electrical issue of some sort. The voltage drops to the point where the Body Processor Module and ECU can't run, and they just black out. Both times it happened to me it happened when I flicked on my high beams. I bet when it happened to you when you applied the brakes and the brake lights came on. The extra load causes everything to black out.

But like I said, for me I had a warning because the headlights were flickering. If I'm ever driving along at night again and my headlights start flickering I'm just going to pull over and "reboot" the car. It happens so rarely that tracking down the problem would be incredibly difficult, and once I restart it it runs fine for another few thousand miles.

 

I didn't notice the lights flickering but I'll keep that in mind for now on. I'd think the voltmeter on the dash would read low as well but ... if the voltage drop is intermittent enough it might not show on the meter. This makes some sense to me but I'd sure like to know the cause so it can be fixed.

Thanks!

 

To follow up, the first time it happened to me it caught me totally by surprise and scared the crap out of me. I was driving down interstate 70 somewhere in the middle of Kansas. The second time I saw the symptoms, pulled into a gas station, and "tested" it by turning on the high beams. Sure enough, the instant the high beams came on the car went black. But then it started right up and ran fine the rest of the way home (a few hundred miles). In Kansas I was actually driving, down the road, so I didn't have to crank the engine to restart the car, it just started up on its own (the key was on and the momentum of the car was turning the engine over). At the gas station I actually had to crank it to start it up, but then it ran fine. It's as if rebooting the car fixes the problem. Maybe the ECU is made by Microsoft.

 

Don't you just love the ways these cars keep providing you with little annoying mysteries on a regular basis? I have had the warning light for the safety restraint system (or whatever it is called) come on sporadically and now it is finally on almost all the time. I called the dealer since this first happened when I still had the SE warranty, but he pointed out that problems with the restraint system are specifically excluded from the SE warranty. Fortunately, I recently bought an aftermarket mechanical breakdown warranty and I went for the Platinum package that has virtually no exclusions. I checked and they said this would be a covered item which I will have taken care of the next time I visit the dealer. But I am always hesitant to visit the dealer for fear of them breaking something else.


Doug

 

I previously relayed what happened to me the night I bought the car and was headed from San Angelo to San Antonio...e.g in the middle of frickin no where (MON). When I flicked on the high beams the radio, and Nav went out and ABS/ASC/Trac Control came on. Later the next night it all went blank but didn't die. When I stopped for gas it failed to restart and everything went dead. Upon retrying the dash lights faded from bright to out...after waiting a bit it did start. Lots of strange things happened later when I got home and was driving around town. It was all electrical related, but the battery and alternator tested fine at Auto-Zone. In my case I had a broken crimp connector on the starter solenoid terminal wire. Since fixing that I have not had any electrical issues. So the broken wire was causing an erratic connection and draining the battery charge I guess (even though it was the solenoid wire which is only energized in the key "start" position).

Let me tell you it was extremely unnerving...unfamiliar highway in the MON, pitch black out, first 100 miles in a strange car (with admittedly a poor reputation that I paid little heed to etc... )

 

You got my attention! Where is this connector located? I want to check it just in case. Maybe that's what has caused my issue. It would be nice to be able to prevent future episodes of this problem.

 

It was probably a fluke; however, you never know. It's easy to see and get too from underneath. There are 2 poles on the starter. The heavy battery cable on one with a larger stud/nut, and the smaller solenoid pole to engage the starter gear into the flywheel. It's a single (approx 16 gage) wire with a crimped on eyelet and is protected by a rubber boot. My eyelet was broken at the wire crimp with the rubber boot holding the wire; just enabling the broken end to touch against the stud. I am very lucky I didn't get stranded on my inagural journey home. It created all kinds of wierd things in the dash, lights, radio, Nav etc.

When I found this forum I first read about having to replace the Main Gauge cluster and was fretting over that large bill. But I was fortunate for the problem to be so simple...finding it was not; but certainly easier by having access with a lift. At my age, 57, I wouldn't work on cars without a lift. I haven't had to use floor jacks and jack stands for 10 years.

 

Amen to that !! Best 'tool' I ever bought.

 

hey guys,never use your transmission as a brake.unless needed in an emergency ,your putting all the weight of the car on the trans, and this is not a good thing.i learned this the hard way as a teenager,trust me or ask a wrench.brakes pads are a lot cheaper..steve.

 

With a decent trans there should not be that much of an issue with downshifting for braking action. If there was, why all the hubbub over the last few years with providing paddle shifters and touting cars with shiftable automatics?


Doug

 

I'm certainly no 'wrench' but I have to disagree that putting all the weight of the car on the trans is not a good thing. Physics being what it is and Force being equal to Mass times Acceleration, the force exerted on the trans during acceleration forward is much greater than the generally gentle deceleration force during a downshift.

That said though, if the trans is somehow designed to be stronger in the forward direction, Steven may have a point. Seismic Guy's counter point is that with all the 'manu-matics' out there, a downshifting design weakness is unlikely. Finally, the Jag J-Gate design is an early 'manu-matic' approach, hence I'd tend to agree down-shifting is likely to be OK.

Any 'wrenches' (not wenches, Rev Sam!) care to comment?

 

I don't know about automatic transmissions, but about 25 years ago I learned my lesson about downshifting with a manual transmission. I had a Datsun 210 with a 4-speed. I would ALWAYS downshift to slow the car. It was like a game I played with myself to see how little I could use the brakes. I thought I was preserving my brake pads and saving money. Then the clutch started to slip going up hills. I had to ease up on the gas while climbing hills just to prevent the clutch from slipping. Then when I tried to accelerate from a stop light the clutch started slipping. I had saved my brakes at the expense of my clutch. It turned out that new brake pads were about a tenth of the cost of a new clutch. After that experience I quit using the transmission for braking unless I was going down a steep hill.

 

Braking with an automatic tranny is an exercise in equipment longevity. You are betting that your tranny friction pacs can last through it and the tranny is trying its best to fry the friction clutches in the drivetrain. Its a matter of time before your tranny wins the wager. If you have ever looked at the clutches you are using to slow th ecar, you will see they are about 7" in diameter and about 1/8" thick the same thing as a multiplate motorcycle clutch. They are pretty tough but you cut their life substantially by using them as brakes. Very poor cost management.

 

Back to the original question. Pulled into the driveway with wifes '07 x-type. Ten minutes later went to start car again. Dead. The North East road salt did it's job on one of the starter cables. The cable bouncing off the starter and what ever else is near it blacked out everything. 1 hour with AAA and 1/2 hour at dealer. No cost, back on the road. Jack