Hey there gang, I'm ashamedly ignorant about all things mechanical. Here is a very unusual problem that my 97 xj6 has presented to me.

The few people I know that are good on cars, fix up their own and all that, were stumped by this. I'm very interested in reading the knowledge that the experts on this site have to offer.

I go to start my car one day--no crank. I hook up the jumper cables and it starts up immediately. Several days later--no crank, it won't start. I jump it again no problem. It works for several more days until one day at the gas station after pumping, I go in to start her up. The key turns on lights, radio, power windows, but no crank at all. When a friend comes to jump me, nothing happens this time. The cables are ineffective and engine won't even try turning over. It's 1am and I call a tow that doesn't arrive until 2am. That whole hour waiting, I tried unsuccessfully several times to start the car. The truck tows my car to my place, about a 6 minute drive, drops off my car, and as he hands me my keys I tell him "with my luck it's going to start now", well it does. It starts up with no problem. I pay the man and shake my head. Please don't stop reading

The very next day I turn her on with no issue and head over to O'reillys to test my battery. The man tells me the battery and alternator are both fine, I explain to him what's been happening and he blames the whether, haha. Well it was fine for several more days until one fateful afternoon when trying to go home from school it once again refuses to crank up. Depressed, I sit there in my car, every 5 minutes putting the key in and turning it hoping it will just come to life. After about 45 minutes it starts up and I head home.

Folks, this was about 2 months ago. My car hasn't refused to start since then. A problem that was beginning to occur with more frequency, and with signs of further deterioration, has now seemingly vanished. What the heck is going on?

 

Hi stupid,

I feel terrible addressing you by your username. No offense intended, and I'm sure you're really quite intelligent.

Intermittent problems are always the hardest to diagnose. It's so much easier when sometthing just stops working for good.

The starter control circuit includes the ignition switch, Body Processor Module (BPM), the Park/Neutral switch (in the rotary switch on the left side of the transmission), the starter relay, the starter solenoid and the starter motor. Your issue could be due to a problem with any of those components, the associated fuses, or the wiring in between.

The starter circuit schematic is on pdf page 43, which you can download at the link below courtesy of our member Gus:

Jaguar X300 Electrical Guide 1995
Corrosion or looseness on any or all of the electrical connections between the battery and starter are known to cause intermittent starting problems, so disconnecting and cleaning the battery terminals and all other power connections up to the starter and alternator would be worthwhile, as well as cleaning all associated ground points, including both ends of the engine ground strap.


The next logical diagnostic approach would be to use a standard voltmeter, begin at the starter control wire, and work your way upstream until you find the component that is not forwarding voltage when the key is turned to the Start position. However, since the Starter Relay is easily accessible in the group of relays near the air filter housing, it would be worth first swapping in one of the nearby similar relays to see if the starter will then work correctly. Here's the location of the Starter Relay:



If swapping relays doesn't work, you could check for correct voltages in the relay socket and if you find a problem, check Fuse #3 (25A) in the Left Hand Engine Bay Fuse Box, which provides constant battery power to the Starter Relay, and Fuse #12 (10A) in the Right Hand Engine Bay Fuse Box, which provides the temporary Ignition Switched voltage to the relay when the key is turned to the Start position.

You may find similar symptoms and possible resolutions in this thread compiled by our member aholbro1:

https://www.jaguarforums.com/forum/x...-120221/page2/

Please keep us informed.

Cheers,

Don

 

****ing relays.

I had pretty similar problem, it was the damn ECU relay, its located behind the front right side headlight, next to washer water refill, together with 2 additional relays, all three of the *******s colored in black. Swap it with the fog light relay, or purchase a new one (it`s not expensive).

I still own LadyPenelope a truckload of beer for helping me out with this.

 

Hi, this also sounds very similar to when my linear switch in the gear selector failed!

if it happens again try wiggling the gear stick while turning the key or starting the car in Neutral. Sometimes a clean or bit of adjustment is all it needs

the linear switch is part no.29 in the attached picture, there is also a troublesome microswitch fixed to the mounting plate no.20

Good luck I hope you find the problem and regain peice of mind

Marc

 

Try removing the battery terminals, clean them, reattach and tighten. It ‘may’ be that simple..

 

Wow thanks a lot guys I truly appreciate the input and suggestions. I can always count on well put together and informative replies from here. I will be using this page and hopefully one day reply with a successful solution, but please don't hold your breath folks. Still, the solution to my problem no doubt lies within one of these posts. I thank you again folks.

 

Hey Marc, so you're saying the linear switch could cause the car to not start up? Incidentally, my car has this strange quirk when it's been parked for several hours (and this doesn't occur every time but quite often) when I press down on the break to switch to drive or reverse it takes about 3 seconds until it clicks and I can maneuver the gear stick. sometimes it will click and I still can't move the gear stick, then it will click again and it allows me to. It isn't too annoying. Any relation to the linear switch?

 

Hi. Yes if the linear switch isn’t quite registering the car is in park you’ll have ignition lights but no crank.
not coming out of park sounds more like the solinoid No.1 in the image
another known issue and again a clean might be all it needs. Fingers crossed

 

Hey gang, so i replaced the starter with a new one about 3 weeks ago and that seemed to fix the problem. If you recall, turning the key would turn lights on but no crank. Finally the jag was starting just like it should, up until this very day. Turning the key after stopping at an autozone, no crank. My problem persists. I sat there stunned cause its been working flawlessly after starter swap. I turn key two more times to no avail then sat there for 5 minutes. Then she started up. Im thinking ignition

Anyway just wanted to update

 

Have you replaced the goddamn relay or not???
If not, then it`s useless to discuss it further. It costs couple of bucks and can be replaced in 30 seconds.

 

One thing you can do is feel for some relays to click as the starter fails to rotate

http://www.jagrepair.com/images/Auto...1996%20LWB.pdf

See page 17

Starter Relay , as the final relay that must close

The starter relay can be swapped with the # 1 fog lights relay

The # 9 RH engine fuse box relay ( referred to as the ignition positive relay ) ( can be swapped with the # 7 LH engine fuse box relay as this one only gives you your horn )

There is 2 halves of the starter relay , the power half to close and provide the power to the starter and the control half which makes the relay close

At point 32 circle double hash the control half gets it's power though the RH engine fuse box relay on page 38

The control ground for the starter relay goes through the linear switch on it's way to the BPM as mentioned

The large ECU relay # 5 is not involved in this case of starter operation

Looking at the 96 year wiring guide which is clearer

http://www.jagrepair.com/images/Auto.../jagxj1996.pdf

See page 45'

Editing

 

G’day Mr Stupid,

All the previous advice is good though I had an intermittent starting problem with my car, a 1995 XJ12, and it turned out to be loose connections on the cable from the battery to the starter.

I’d be checking all these connections first. The cable starts at the battery and goes inside the car and under the rear passengers seat on the RHS there is a big connector and a couple of high capacity fuses. Then the cable goes under the carpet to a connector in the RHS front footwell where it passes through the firewall, from here it goes to the starter and then the alternator.

All these connectors are bolted together and can loosen as the car ages, lots of things loosen as they age, and these loose connections affect the amount of current that passes through them. You can easily lose a couple of volts between the battery and the starter which will mean you get a no crank situation as I had. I replaced my starter and the problem went away for a while but eventually returned.

I finally got around to checking, cleaning and tightening all these various connectors and that fixed it, for good.

Cheers and and good luck,
Jeff.

 

sorry howitzer forgot to mention. When the mechanic changed my starter he called me to say the car is now starting but shuts off. I was infuriated because naturally i was in disbelief. The only issue the car had was not cranking to start, now it was not running??? I'm thinking BS in my head but i tell him go ahead and figure it out. I knew it would be nothing, i knew it was one of those things to get more of what little money i have out of me. So they charged me another 120 to diagnose and found it was this little guy. If i recall, they said this was the fuel pump relay? Im such a nitwit i dont even know if such a thing exists. Anyhow, after the new starter, and this new little box, car was running great. Yesterday, when it suddenly didnt start for me at an autozone, i had been driving all over the great state of texas with no issues. Im back home and the jaguar has been starting every time but im worried the problem is still present. Obviously

Thanks for the input from other users. I bet a lot of people read my posts and wonder why someome with such a lack of knowledge about the mechanics of a car would purchase an old jaguar. Well thats why im stupid. Still, no regrets here. the car has been so good to me in the 4 or 5 years ive had it. It is I that has let it down

 

A both related item in the starter not rotating and the engine stalling after start is the RH engine fuse box relay ( ignition positive relay )

This relay both provides power to close the starter relay and it is well the first source of power to the ECU

The ECU controlled relay is the second source of power to go into the ECU

The fuel pump relay can be tricky to troubleshoot as the relay is closed for only 4 seconds on initial key rotation , The relay will close again once the ECU see engine rotation

Jaguars follow the same physics as any other cars