My wife had not been driving her car very much recently. The last time was 2 weeks ago, and before that was almost a month. Yesterday she tried to start it and - NOTHING!

Assuming the battery was too low I hooked up my charger (BatteryMinder 2012). After about 4 hours, it still showed 'next to lowest'. I left it on all night and this morning it showed a full charge. Tried to start it, but still nothing.

The dash lights & display come on normally. The fuel pump runs for a couple of seconds, and there is not even a click of a starter relay. I get no error messages on the dash, nothing is set on my OBD II reader. I tried starting it in Neutral but to no avail. I also tried disconnecting the battery & shorting the cables together. The alarm went off after I reconnected & opened the door, but it shut off after I pressed the unlock button on the key. All fuses check OK.

I also noted that the parking brake released when I moved the gear selector out of Park, and re-engaged after going back into park & the key was removed.

As it stands, I measure 12.6 V at the battery, 12.25 V with IGN switch in pos III, and 12.14 V with the switch in 'start', and back to 12.6 V with the switch off again.

The battery (Interstate) was replaced just a year ago. The car only has around 55K miles on it and has run beautifully up till now.

I really can't afford a trip to the dealership (yeah, shouldn't own a Jag if you can't afford outrageous repair bills!). None of the other threads I found on this topic have given me any further information. (I wish I had measured the battery voltage before charging it.)

Any good ideas?

 

Someone may know for sure but that seems to drop a lot more than I expected.

 

Turn the lights on for 3 mins and then check the voltage on the battery if it is lower than 12.6 volts. Then try to charge it once more.

our cars don't produce a high enough voltage to fully charge maintenance free batteries. The majority of the time we only charge them to 80% of capacity. They need 14 volts and the s type only produces that just after starting then it drops to 13.4.

I run my car fairly regularly but not everyday so I have the battery on a tender to make sure that everything is alright.
The tender is a ctec mxs 5.0 which are quite cheap now from Amazon and other places.

 

Would you settle for a so-so idea?

When you tried to start in Park, was the P illuminated on the J-gate bezel? Same for Neutral. Was the N illuminated?

Those indicators do not show the position of the shift lever. They show the position of the neutral safety switch on the transmission, at the far end of the shift cable. If the shift cable had come loose or the switch had failed, the starter will not engage until that switch sees either neutral or park.

 

Thanks to all who replied! I ended up charging the battery for another 30 hours. This time the voltage was up to 12.8V. I tried to start it again - still nothing. I then checked that the Park & Neutral indicators lit up in their respective positions; both were OK. I then tried starting it again, this time it started normally.

Huh? I checked the charging voltage - it started out at a little over 15V, then dropped to 13.6V after a while. Let it run for a few more minutes, shut it off & checked the battery: 12.8V. It started up again just fine. Readings same as before.

I'll check the battery voltage again tomorrow morning to see if it's dropped much.

My mechanic buddy has offered to do a swap-out of my 'old' battery for a new one next week anyway (he's an Interstate dealer).

(hopefully, this saga will not be continued...)

 

Fault still present. Then your next sentence:


Suddenly everything worked. What changed? Just by checking the P and N indicator lights, that means you cycled the shift lever.

My TheoryDuJour™, subject to wind direction and the nearby presence of squirrels:

The neutral safety switch is intermittent or slightly out of adjustment. From some quick research, it looks like the late model J-gate and neutral safety switch is different from the early version with which I'm familiar. You may want to look into this a little further. But if the problem returns, try fiddling with the shift lever and see if that lets the starter engage.

 

I certainly hope that I won't get another opportunity to check this out further!

I did note that the P indicator was lit before I tried (unsuccessfully) to start the car today. Also, yesterday I had tried some serious fiddling with the shift lever whilst holding the key in Start. Yesterday I also tried moving the lever from Park to Neutral a couple of times, trying to start it in each position.

I can hear the mechanical (I think) sound of the switch being engaged and disengaged when I move the lever from side-to-side in Park, but I also noticed that the P light was still lit throughout all of that motion.

When you say that the J-gate is different, are you referring to the mechanical, or the electrical layout?

ps - We always have many squirrels present nearby, but tonight we were also treated to Mama Skunk and her 4 or 5 young-uns wandering about in front & behind our house - no doubt looking for spilled bird seed in the back yard, and grubs, etc that might have come out after the 24 hours of rain we just enjoyed. I took some pics & a video of the dance.

Cheers,
Joe

 

Both.


Further muddying of the waters here:


https://www.jaguarforums.com/forum/s...8/#post1713330




The later model gear position sensor, the part that tells the starter it's okay to engage, appears to be 4 proximity switches, not the mechanical contacts like in the early model. If electronically driven, they may be more susceptible to low voltage.


My TheoryDuJour™ (not to be confused with yesterday's) is you may have low voltage before start, and the transmission can't determine what gear is selected. It won't let the starter engage if it doesn't see P or N. Try keeping the battery on a charger for a while and see if that clears it up. If so, then you'd know to investigate low voltage, possibly a marginal battery, etc.

 

Ignore all previous theories. Rantings of a madman...

See this thread:

https://www.jaguarforums.com/forum/s...-p1797-142604/

Even though the symptoms aren't identical, it might be worth crawling underneath to make sure that connector is secure. That's my latest TheoryDuJour™.

Look, a squirrel!

 

Short reply:

I tried to start the kitty this evening; it started OK again, but I forgot to check the battery voltage beforehand, so I'm still not satisfied that the issue is solved.

Karl, thanks for making this problem even more complicated than ever! I will check all of the possibilities you linked to, so a genuine thanks this time.

Now if I can manage to get my tired old body underneath the car when it's up on ramps. Even a creeper is a problem for me these days.

I'll give an update as soon as I know more.