Hi everyone, I recently purchased a 1998 Xj8. The car was being driven daily until one morning it presented with a no crank situation. The owner thought dead battery, put one in its place to no avail. He shortly thereafter was convinced it must be his one and only key lost programming. Enter present day, I’m intrigued and buy the car from him.
initialy I went out and purchased the correct new battery for car. Started reading a little about the car, and that this is a somewhat common occurrence.so I then proceeded to look over all the fuse boxes and looked at relays for signs of a problem (burnt etc) and found nothing. I quickly supplied power to the starter solenoid and verified the engine would turn over and that the starter itself was not the issue. Doing this I realized that I had no fuel pressure on the rail. So I continued my research and also had a friend come by with a scanner to communicate with the cars computer. He was unable to connect with the vehicle for reasons unknown and I continued on.
so as time goes on I drummed up schematics on the vehicle and some control module pin-out information. I should also mention during this time I cleaned the ignition cylinder, and driver door lock cylinder. I then realize that I could lock, unlock, roll windows down, and roll windows up from the drivers door, outside the vehicle. This led me to roll down the window, lock the car and reach in to unlock, setting off the alarm. I could then open the door and use the key to silence the alarm. Hmmmm, makes me think the key is not the issue. I have since learned this may not be the case. So after a lot of staring at modules and tracking wires down I thought for sure it was the BCM. I forgot to mention a click from there when I attempt to crank the engine. I quickly came across a used one with matching numbers so I purchased it. When it arrived I unhooked the battery swapped the module, and did a hard restart. Nothing changed.
I hope someone has a few things, concrete things that I may be able to check. I have no desire to visit a dealership as there isn’t one near to me and also it would require a flatbed tow. I am now tempted to buy the ECM, KTM, cylinders and keys from another vehicle as I see this option come up a lot and I assume does not require reprogramming. Help!
thanks in advance……
confused.

 

Module failure isn't all that common. I wouldn't start swapping modules without associated error codes giving firm evidence of failure as there's the immediate issue of programming/compatabilty.

You have gone through a logical sequence and I agree this has eliminated remote/key as a possible cause. The sudden failure after a reliable daily driving history and the fact you can power the starter solenoid directly makes me suspect the HPPM (High Power Protection Module). Loose cables or breaking terminals are a regular for preventing the start motor turning.





I'd check and eliminate this before looking for more complex (and inevitably more expensive) possible causes.

Graham

 

Thanks Graham, I’ll check there right away. I remember doing voyage checks there, but will check again for sure.
mom with you in saying, I’d rather not get involved in changing (chasing) a bad module.
thank you and I’ll let you know what I find.

 

There is also an emergency cut off device (immobilizer)), but it is in the passenger compartment: you will need to pull away the card by the right foot. And press the button. Sometimes, when parked, a car will get hit which will trip the immobilizer. Search the forum for details (and your Drivers Manual).

Second choice would be to reprogram the key. Third choice would be lack of voltage through the false bulkhead. Fourth would be bad relay connections (see relay boxes on the port side of engine bay). I second the opinion to leave modules alone: too many other choices that need to be negated first . . .

Attached might help:

 

Ok guys this morning I started with power distribution, didn’t find any issues right away. When I was up front checking voltage at the fuse box locations in the engine compartment I noticed that the right side of the engine control fuses had no voltage on them. With the key on I showed a tiny amount of voltage only, however I had 12.4v to the relay. I jumper the relay and several things came to life that I have yet to hear. Including, I believe the fuel pump. I could hear other relays contacting over by the starter relay. However from the key the engine will still not crank. All I hear is relays under the back seat and a click behind the glovebox seemingly from the BPM. I certainly thought I had solved the issue. Weird thing is that I tried other relays and they didn’t seem to work as the jumper did. Could I have a whole slew of bad relays? I also notice the windshield wipers are not working. Help!

 

Did you check the voltage on each side of the false bulkhead?
This is known to fail. It happened on my 98 x308. Intermittently a no start and not charging the battery.

 

Thank you, yes I have checked it. It has been removed from its location and was taped so I was drawn to it early on. If I remember correctly it seems like In the beginning I saw voltage at the starter relay, and when cranked it would drop out, which is correct for that circuit but I cannot be certain that it still is or not. I definitely need a helper to check some voltage drops across certain components. Also has anyone encountered this issue with the fuse block? I ask because I had a minivan once I was working on that had the strangest symptoms. Long story short I pulled the fuse block and there was rust and corrosion everywhere. Proceeded to clean all that I could, and it solved all of my problems. Yep two days later the engine threw a rod…….

 

I had a similar issue a couple of years ago, it was a totally dead scenario....no parlor lights, no fob controls. Found the lanyard mesh ground coming off the battery was bad. Inquired with my Tech about it and he had one in his hand he had just replaced off an XK. Kind of answered that.

 

Highhorse, it’s amazing to me that it takes so little to cause SO many different symptoms. The programming logic blows my mind. 🤯

 

Actually it proves that some of the simplest solutions are basic grounding procedures. Folks tend to complicate things because the problem may be from a complicated device and determine the solution must be complicated, ..when its actually as simple as a properly grounded strap.
If the ground isn't the solution, then you can move on to other solutions. But without proper grounding, those other solutions don't mean squat. You'll see many responses here start with checking grounds, these cars are out of their teens and have been exposed to the climate for over 20 yrs.

 

lost key will throw a code. when you turn the key and radio/accessories will shut off to provide max cranking amps but PATS obviously denies a ground to the starter relay


get a $5 scanner and try to talk to it over 9141

 

When you turn the key on, is the “P” by your shifter lit up? Also, shift it into neutral and try starting it. I doubt this is your issue as you mentioned messing around with something else made quite a few things light up.

Have you checked out the ground cable on the bottom of the engine? They can get pretty crusty over the years.

I’ve had one X308 in the 9 years working on these jags have a bad fuse box in the engine bay so it’s possible you could have one as well.

This recently purchased BPM won’t make your wipers work, did the previous one make them work? I do know there’s black wiper relays next to the ABS module on a bracket.

 

Thank you, and I am checking the lower engine ground strap today. I have since starting this thread, changed both positive and negative battery cables. I found a cracked cable clamp on the positive side which led me to change them. I also pulled both engine compartment fuse boxes and cleaned all connections and checked for damage. None of these seemed to solve my problem however. I also began investigation of the wiring harness for the trunk lid. I went this route because I do have a message indicating that it is open that will not go away on the dash (Among others…. Trans fault, incorrect part fitted, failsafe mode etc.) I haven’t found any damage to the harness yet. I did notice the light in trunk wasn’t working, bulb blown with v+ at the socket. Jumper out the switch and lost v+ telling me the switch is working. So dead end on that little investigation this far.
I should mention, I also was able to borrow a handheld scanner, but as per other attempts it refuses to read the codes. Any advise on this would be greatly appreciated.

Also any easy way to check for relay operation that may be escaping me at this time? I get this feeling like I have several that are not working at this time.

thank you everyone in advance!

 

Some relays will only come on once the engine has started so it is not easy to tell which ones should be "on" at ignition key "on" and which ones shouldn't. As to the no-crank, you should also check the in-line connector circled yellow on the picture. It is on the wire that goes directly to the starter solenoid.

 

So it’s been quite a few days since I’ve been able to get anything done with the car. This is partially due to mass confusion surrounding the issue. Today I was finally able to get some diagnostic tools to work for me involving this car. So…. The climate control module was showing B1948, B1265, B1858, B1863, and B1258. I also had U1260, and U1261. Haven’t had much time yet to research any of this info but thought I would share it here while I do. Thanks in advance for any ideas or thoughts.

 

Hello key key key. I went through this with two cars last spring xjr xj8, I was pulling my hair out couldn’t get anything except a click when you turn in the key I live in a small town so I had to order trippy keys off of eBay when I got delivered I used another guy locksmith off eBay that could cut a key with just a photograph of the original. Then I’d mail him a key blank he would cut it sent it back to me then I had to take the car down to the locksmith who could program it instant start on two different cars. . It be about $100 total cost for one key of course I’d have them do extras I didn’t wanna have to go through this anymore. I’ll bet this kills a lot of these cars.

 

if your fuel pump works you will hear it run during cranking

 

Vonnslingo, thanks for your thoughts and I wanted to go key for a long time at first. Problem is that I can do everything else with that key, including de-activating the alarm. Seems odd I could roll the windows and work the locks either but I can. Have you ever heard if these codes causing the same issues?

 

ignition is separate from everything else. any key will unlock and lock the car all the day

normally when it doesn’t recognize the key it doesn’t let you crank

 

Time to get all keys reprogrammed.