Jaguar 2002 S-Type 4.0L
Major symptom: Car does not start (nothing happens when key is turned - does not crank); battery is fully charged; unhooked neg terminal on battery, waited 30 sec and re-attached; at this point all systems seem to come on (interior lights, radio, etc.); when door is opened or (if door is already opened) key is turned in the ignition, the alarm goes off until neg cable is pulled.
First signs of a problem seen in early September. Local mechanics didn’t have diagnostics to deal with it. Had it towed 30 miles to dealership in Austin. Dealership found shorted wires and traced starter circuit; missing fuses and “chewed” wires in center console…repaired. There was rodent damage. Calibrated yaw and pitch rate sensors. Replaced battery.
Two weeks later car showed same symptoms. However, when I disconnected and reconnected battery twice it started and I drove it to dealership. They kept it and it started every day, so could not diagnose.
In October, when car was left for 3-4 days without starting the original symptoms returned…would not start. When I unhooked and re-hooked battery (to reset computer) it had the same problem (alarm engaged). As a biologist, it behaves like a seizure…all electrical systems come on at once but there is no engine response when turning the ignition. Again, towed into Austin. Found additional wiring damage and fuel pump electrical failure. Replaced fuel pump. Replaced wire to idle air control and fuel pressure sensor.
Drove home and it worked fine for a couple of days. Did not use for 3 days and the original symptoms returned today. Dealership wants it back but I can’t start it.
Questions: Does anyone have any idea what the root problem mighth be? I got rid of all rodent problems and have snap traps out in the garage. Don't see anymore rodent damage but I guess there could be. But why would it start normally if used every day, but stop starting when left idle for 2-3 days? Does anyone know how to circumvent alarm to get it started? Original invoice mentioned “jumped starter relay to get started”…how do you do that?

 

David, losing electrical conductivity may indicate a short may still exist. Too much is happening, have her towed back to the dealership. Here, they'll continue to rectify wiring faults and they should keep the car for a few days as a means to allow them to experience the same set of circumstances that you endured. When performing a hard re-set of the ECU, remove both the positive and negative from battery then keep them touched together for 30 seconds.

 

How do you know battery is fully charged? (We don#t know your abilities/knowledge and batteries are trickier than many think.)

Similarly, how do you know it's in a fit state? (They can die in surprising ways.)

 

+1 on JagV8.
Dodgy batteries are the most common cause of 'bizarre' faults.
Have it discharge checked at somewhere like autozone.
If it's OEM the date will be stamped on the neg post - see how old it is and consider a replacement anyway if it's 5+ years old.
If that doesn't work keep posting!

 

Battery s new and strong when it engages. I was a car guy through my 30's but haven't worked on one since then (I'm 65)...once the engine became a large black box and my knees got in my way. Thanks for the advice.

 

You can't bypass the alarm (immobiliser) nowadays as they're scattered throughout the computer modules and basically they agree on whether to allow starting. Things like injectors / spark plugs tend to get shut off if not. It stops most attempts at theft.

However, if the car is intentionally doing that (for whatever reason) it is likely flashing a PATS (see my sig) code on that red light top centre of dash. Watch it as you try to start and for a min or 2 after before turning key from Ignition II position. Try to count the pattern of flashes, if there is one.

 

Will do later today. What am I looking for in the pattern? A pause in which it will crank?

 

Wiring damage does not "just" happen. You have stated that the car has suffered twice from damaged wiring. Your problem is being caused by whatever is doing the damage.

Wiring is a very difficult problem to troubleshoot on any modern car and especially on something complex like the S Type. Codes will be of little help as they will only show what is not working and do not indicate any wiring problems.

Does the car have any codes? This can at least give us a direction to look for more wiring problems.
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The wiring damage was caused by rodents (field mice) nesting in the trunk. We didn't realize they were there because they were in the tire compartment. We have since cleaned out the car and the garage and set out traps...there will be no more wiring damage. This damage was "fixed" three times. There is probably more but I need to get it to the shop to isolate the problems. Since it won't start I get no codes. I will persist and get this solved...it's too nice a car.

 

Glad you found the nest! Yes the damage could be anywhere and all over. Did they get to your upholstery any? I would be worried about the nice leather interior.
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To get codes / check modules, you don't need to start the car all you need is ignition on.

However, with that type of damage there is a risk of fire. You've probably ruled that out as it would presumably have happened by now.

The real jag tool can check individual modules & sensors scattered throughout the car but it takes time. If you've the patience and time you could get your own tool. (It can also command actuators.)

This sort of damage is as said above one of the worst things that can happen, unfortunately.

Be aware that damaged wiring can confuse modules. They can report weird codes. They may fail to shut down as intended, thus draining the battery even when the key is out. Sorry to be the bringer of bad news.

 

During the alarm the red light on the dash flashes constantly. When the alarm stops it flashes 5 times, pauses, flases once, pauses and then repeats the cycle.

 

Looks like PATS code 15.
If so, it's Key not programmed. Which may in effect be one module involved in security/immobilisation can't successfully talk to another so decides not to start. Though I reckon code 16 would perhaps be more likely.

Probably my last post still applies.