XJ XJ8 / XJR ( X308 ) 1997 - 2003

hard reset

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  #1  
Old 06-17-2010 | 08:17 PM
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Just for fun, I was going to do a hard reset.

The proceedure is: Unhook negative battery cable and touch to positive cable while the positive is still connected to battery??

Is that correct???

For 5-10 seconds or so?
 

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06-20-2010, 12:45 PM
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wow I guess Ive been doing a hard reboot wrong all these past 13 years........
For ya'll that dont remember, you have to have a COMPLETE circuit for power to flow. If the negative(or pos) is unhooked from the battery you can touch the DISCONNECTED negative to the STILL CONNECTED(or visa/versa) Positive. There is not a complete circuit and no power flows. you can disconnect both if you feel more comfortable, but its not neccessary, it just takes more time. The reason I and others say disc the negative is 2 reasons
1) it useally the closest and easiest to access
2) theres is useally little or nothing else hooked to it
The reason it works on the capacitors is THEY still have a complete circuit on the car so you are giving their positive terminal a path to ground to discharge them. And since the ignition provides a mechanical link to circuits that are isolated. You can/should also switch the key to the on position while the battery is unhooked and hard reboot again. Then shut off the key and go back and reconnect the battery.....and no a hard reboot will not clear codes on ODBII. While it MIGHT, turn off a check engine light(depending on WHAT, the stored codes are) they DO NOT go away. There are codes that will only show when active/pending, and if you shut off the ignition they may not show even with Jaguars IDS(again it depends on the code/situation)
 
  #2  
Old 06-18-2010 | 05:22 PM
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I think about 20-30 seconds is the usual time. Worked for me.
 
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Old 06-18-2010 | 08:00 PM
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OK, I give....wat's a hard reset? And what does it affect?

Michael~
2002 XJ8 VDP
 
  #4  
Old 06-18-2010 | 08:52 PM
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Like your PC, the computers in the car sometime get 'confused' and need to be rebooted. Everything gets to start over at factory settings. The only thing that takes a day to get over is the fuel trim.

As described, touching the negative ground cable to the positive battery post discharges all the little capacitive voltages and 'reboots' all systems. Takes only a moment. No sparks, no arcs.
 
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Old 06-18-2010 | 10:18 PM
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Thanks TP, I appreciate it. Figure it can't hurt and have tried everything to get rid of all the codes.

I've found a few breather/vacuum issues and fixed those, but nothing has solved my codes. 1516, 443 & 507.

Still get failsafe, then limpmode w codes.
Cleaned tranny plug, MAF, TB, Part breather, "T" breather

Getting pretty frustrated with the whole situation.
 
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  #6  
Old 06-19-2010 | 12:32 AM
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please, dont touch the negative cable to the positive battery terminal.

you want to ground out the power from the circuits to the chasis, not from the battery to the chasis. thats very dangerous !


disconnect the positive and negatives cables, and touch the 2 together. Even simple 1 seconds contact will be fine, but let them touch each other for 10 minutes to drain the power from the capacitors in the cars ecu's.

like I said, DONT touch the negative cable to the positive battery post.
 
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  #7  
Old 06-19-2010 | 12:36 AM
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ok and one more thing, if this is a naturally aspirated XJ... On my fathers 2000 vdp I was getting all those codes. The limp home ,failsafe crap. Did all you mentioned, they went away with all the stuff you did.

from time to time I would still get a restricted performance, 2 months later bye bye a-drum in the transmission. first gear was gone.

Another member on here noted that he saved his transmission by getting the code read at a dealer and coming back for the trans. Got a new a-drum off of ebay for $240 and repaired it himself...

If the codes go away with the hard reboot, fine. If they come back, look into the transmission. Would suck having to spend $3000 when $900 w/labor with be better plus save you a break down.

-vic
 
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Old 06-19-2010 | 10:08 PM
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Originally Posted by StrateLoss
ok and one more thing, if this is a naturally aspirated XJ... On my fathers 2000 vdp I was getting all those codes. The limp home ,failsafe crap. Did all you mentioned, they went away with all the stuff you did.

from time to time I would still get a restricted performance, 2 months later bye bye a-drum in the transmission. first gear was gone.

Another member on here noted that he saved his transmission by getting the code read at a dealer and coming back for the trans. Got a new a-drum off of ebay for $240 and repaired it himself...

If the codes go away with the hard reboot, fine. If they come back, look into the transmission. Would suck having to spend $3000 when $900 w/labor with be better plus save you a break down.

-vic
Vic,

Great info. '99 xj8. Not sure if the reboot will help, but why not. I was a little suspect of neg to pos. Sounded like a bad idea, but I'm not in a position to argue.

Did his cruise work? This one doesn't. And yes, I blew $70 on a brake switch I didn't need. Prob just sell it.

I'm gonna blow propane around the various hoses/gaskets and see if I missed a leak.

I'm open to any suggestions.

Regards,

flyfish
 

Last edited by flyfish; 06-19-2010 at 10:09 PM. Reason: add info
  #9  
Old 06-19-2010 | 11:06 PM
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I dont know, dont use cruise around here. too much traffic and tailgating.

But, if/when the codes pops up. the best thing you can do is go to the dealer to get it read. it will be the wisest $120 youve spent on the car if it infact does point to the transmission
 
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Old 06-20-2010 | 01:31 AM
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I have a reader so I can see and clear codes. Unless autologic is gonna send up a flare from the trouble spot, i'm not sure what value the dealer can provide.

Not having any tranny issues that i'm aware of.
 

Last edited by flyfish; 06-20-2010 at 01:39 AM.
  #11  
Old 06-20-2010 | 08:39 AM
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Disconnecting the battery, even forever, does not reset fault codes. This "Reset" or "reboot" process does not do what people have come to think it does.

Diagnose faults the correct way, using a scan tool, finding the fault and correcting, then resetting the code after any necessary monitor drive cycle is performed....now you're talking.
 
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  #12  
Old 06-20-2010 | 10:52 AM
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Im guessing you have an OBD scanner, thats not going to read out Jaguar specific non emissions codes that Im aware of. When I had my "park brake fault" amber warning, took it to autzone for a free reading and got nothing. Came up like no light was on, because its a Jaguar code.

Now Jaguar can read those codes and can use it to see whats wrong and where.

My fathers 2000 had nothing wrong with the transmission, untill the minute it popped. But the codes kept coming on and the car felt normal. The other user on here described the same problem.

This is free advice, what can I say. But that blown 1st gear on my dads car pretty much ended that cars life. We wont fix it, and will probably end up being away to someone. And it was a beautiful british racing green VDP.... a shame IMO.

-vic
 
  #13  
Old 06-20-2010 | 12:45 PM
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wow I guess Ive been doing a hard reboot wrong all these past 13 years........
For ya'll that dont remember, you have to have a COMPLETE circuit for power to flow. If the negative(or pos) is unhooked from the battery you can touch the DISCONNECTED negative to the STILL CONNECTED(or visa/versa) Positive. There is not a complete circuit and no power flows. you can disconnect both if you feel more comfortable, but its not neccessary, it just takes more time. The reason I and others say disc the negative is 2 reasons
1) it useally the closest and easiest to access
2) theres is useally little or nothing else hooked to it
The reason it works on the capacitors is THEY still have a complete circuit on the car so you are giving their positive terminal a path to ground to discharge them. And since the ignition provides a mechanical link to circuits that are isolated. You can/should also switch the key to the on position while the battery is unhooked and hard reboot again. Then shut off the key and go back and reconnect the battery.....and no a hard reboot will not clear codes on ODBII. While it MIGHT, turn off a check engine light(depending on WHAT, the stored codes are) they DO NOT go away. There are codes that will only show when active/pending, and if you shut off the ignition they may not show even with Jaguars IDS(again it depends on the code/situation)
 
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  #14  
Old 06-20-2010 | 02:13 PM
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There, BRUTAL cleared it up. When I did mine I just disconnected both. Didnt chance it because I didnt know any better.
 
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  #15  
Old 06-20-2010 | 04:58 PM
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Precisely on OBD codes. They can be present and readable. They are stored in non-volatile memory, But the display is not. So, disconnecting the battery might erase the display but not the fault. Does nothing to complete a drive cycle, does nothing to fix a mechanical issue. It does screw up all the radio mode settings and other customer selectable settings.
 
  #16  
Old 06-21-2010 | 08:56 AM
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I am able to read and clear the codes as they come up w my reader. Only nothing i've fixed keeps 1516 from reappearing.

I don't dissagree there may be additional Jag codes I can't see keeping me from the ultimate fix.

I can't find many occurances of 1516 and its possible solutions.

I do have a wheel vibration and one of the possible faults has to do with the speed sensor. Possible connection??
 
  #17  
Old 06-21-2010 | 09:40 AM
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Default P1516

Did I miss something or this the first mention of P1516?

P1516

Transmission rotary switch to ECM open circuit or high resistance.

Rotary Switch failure

D-4 switch to TCM open circuit or high resistance

D-4 switch fault
 
  #18  
Old 06-21-2010 | 11:37 AM
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Originally Posted by flyfish
Thanks TP, I appreciate it. Figure it can't hurt and have tried everything to get rid of all the codes.

I've found a few breather/vacuum issues and fixed those, but nothing has solved my codes. 1516, 443 & 507.

Still get failsafe, then limpmode w codes.
Cleaned tranny plug, MAF, TB, Part breather, "T" breather

Getting pretty frustrated with the whole situation.
testpoint he mentioned it right here
 
  #19  
Old 06-21-2010 | 01:17 PM
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TP,
I also had a 1516 thread where you suggested I cleanded the plug going into the transmission, which I did.

I know the potential causes, just don't know what they are to check : "rotary switch", "D-4" switch etc
 
  #20  
Old 06-21-2010 | 02:28 PM
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The 'Drive to Fourth' (D-4) switch is in the shift console.

The 'rotary switch' is located on the right side of the transmission.

I would suggest that you down load the JTIS free from this forum and take a look. While some have the software to cut-n-paste the drawings from JTIS I have never found out how to do that.

https://www.jaguarforums.com/forum/s...ead.php?t=9933
 


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