Limp Home 1998 XJ8 4.0L Gearbox Issues...
Discussion
Following a post last week, I had the 'P0706' fault code and have just renewed the rotary switch (for over £235!) but the fault is still there and driving in limp-home mode.
I now suspect the 'D to 4' switch....was wondering if anyone had any experience with these? or any other ideas? I have an electronic manual for the car, but seems there are lots of things that could cause this condition.
Anyone?
I now suspect the 'D to 4' switch....was wondering if anyone had any experience with these? or any other ideas? I have an electronic manual for the car, but seems there are lots of things that could cause this condition.
Anyone?
I'd say it's time to get the car on the Jaguar WDS for a proper diagnosis. Parts are way too expensive to even start going down the "fit one and see" route unless you have absolute proof you know what's wrong.
You might need a new gearbox - or just a shot of WD 40 on a corroded connector. Who knows? Diagnosis is always the most difficult aspect of correcting problems, sorting them out once you absolutely know for sure what's wrong, and you've exhausted all the possibilities, is just spannerwork. Try your local indie for starters, or transmission specalist and see what they suggest.
If you're in the south east give Mike at Wyn Thomas Jaguar a call - he's got a good reputation, or try Honest John's recommendation for a reputable transmission expert nearer to you.
You might need a new gearbox - or just a shot of WD 40 on a corroded connector. Who knows? Diagnosis is always the most difficult aspect of correcting problems, sorting them out once you absolutely know for sure what's wrong, and you've exhausted all the possibilities, is just spannerwork. Try your local indie for starters, or transmission specalist and see what they suggest.
If you're in the south east give Mike at Wyn Thomas Jaguar a call - he's got a good reputation, or try Honest John's recommendation for a reputable transmission expert nearer to you.
P0706 says that there is a range fault, but you need to understand it doesn't mean that you need to throw a new switch at it, it means you need to look at the reasons why there may be a range fault.
It could be shift cable adjustment or the cable going out of adjustment by stretching, it could also be a circuit fault such as a bad earth.
A good dealer would find the DTCs and then follow the workshop manual on diagnosing and repairing the fault before throwing parts at the car.
I would get a quote from a dealer - it may be surprisingly inexpensive.
It could be shift cable adjustment or the cable going out of adjustment by stretching, it could also be a circuit fault such as a bad earth.
A good dealer would find the DTCs and then follow the workshop manual on diagnosing and repairing the fault before throwing parts at the car.
I would get a quote from a dealer - it may be surprisingly inexpensive.
Well, after exhaustive testing this weekend, i have now located the fault. It is the Input Speed Sensor that is 'opn circuit' and needs replacing.
I know that it is inside the gearbox and have all the info about how to fit it, just a little concerned about re-filling the trans. afterwards as it seems not only has it got to be done with a syringe, but does the 'final top up' have to be done with the engine running? It says fluid temp must not exceed 50°c.
Other than that, I'm pretty sure i'm on the road to fixing the problem.
I know that it is inside the gearbox and have all the info about how to fit it, just a little concerned about re-filling the trans. afterwards as it seems not only has it got to be done with a syringe, but does the 'final top up' have to be done with the engine running? It says fluid temp must not exceed 50°c.
Other than that, I'm pretty sure i'm on the road to fixing the problem.
Gear box fill is quite simple. Use the propper jaguar oil. Its like a brown colour rather than red, like normal ATF.
You fill till it comes out with engine off, then start engine, go thought the gears with your foot on the brake, then fill til it comes out with it running.
The final micro adjustement of level should be done when oil is at 30-50 degree's but to be fair, all that happens is very slight expansion as it gets hots, so it will just trickle out of the fill hole until the temp reached. If you dont bother and go with the cold level, it will be very very slightly over filled, and not a big deal at all.
Hope your right about the sensor. That code will be logged if the gearbox slips, and if there is a fault with the internal harness, I done a few of those. Best of luck.
You fill till it comes out with engine off, then start engine, go thought the gears with your foot on the brake, then fill til it comes out with it running.
The final micro adjustement of level should be done when oil is at 30-50 degree's but to be fair, all that happens is very slight expansion as it gets hots, so it will just trickle out of the fill hole until the temp reached. If you dont bother and go with the cold level, it will be very very slightly over filled, and not a big deal at all.
Hope your right about the sensor. That code will be logged if the gearbox slips, and if there is a fault with the internal harness, I done a few of those. Best of luck.
Have ordered the parts today and await their arrival. Interesting about the harness, but it has 'passed' all the continuity checks, and the only failure was the input speed sensor.
I was shocked at the price of the oil though...my dealer wanted £23.80/litre!, I have managed to source some on the web though (Esso LT 71141) for £5.89+vat/litre instead - a bit of a difference!
I was shocked at the price of the oil though...my dealer wanted £23.80/litre!, I have managed to source some on the web though (Esso LT 71141) for £5.89+vat/litre instead - a bit of a difference!
Thanks 'Tame', should have also mentioned the other code found was P1722, and amongst other things, relates to the output speed sensor! but that passed the tests. Just goes to show how full testing is neeeded before replacing parts. Still anoyed with myself for replacing the Rotarty Sensor switch that didn't need it.
Oh well, you live & learn.
Yes, the oil was a shocker, but glad to see some people are selling it at a sensible price!
Oh well, you live & learn.
Yes, the oil was a shocker, but glad to see some people are selling it at a sensible price!
Agree with above about the price of Esso LT71141 from Main Stealers 
Anyone in the South West and has a Jag with a ZF box, I can recommend the following supplier that does reasonable prices also.
www.northwiltslubricants.co.uk
Based in Calne, Wiltshire - ask for Barry. He decants it into 1L and 5L containers too. It is only available from Esso in 20L container originally.
Rgds
Anyone in the South West and has a Jag with a ZF box, I can recommend the following supplier that does reasonable prices also.
www.northwiltslubricants.co.uk
Based in Calne, Wiltshire - ask for Barry. He decants it into 1L and 5L containers too. It is only available from Esso in 20L container originally.
Rgds
Can thoroughly recommemd NorthWiltsLubricants now, got a couple of litres to 'top-up' hoping (against all hope!) that it may ease the problem.
No good, so have now drained all the oil, cleaned everything, renewed the oil filter, and am just awaiting my next delivery of oil to re-fill; just really hoping now, that this will be the end of the saga!
The guy at www.northwiltslubricants.co.uk (Barry I presume) has been very helpful and shows good knowledge of the boxes and stated in his experience, that a complete oil & filter change to the trans, often cures any faults - Just hope he's right on this occasion.
No good, so have now drained all the oil, cleaned everything, renewed the oil filter, and am just awaiting my next delivery of oil to re-fill; just really hoping now, that this will be the end of the saga!
The guy at www.northwiltslubricants.co.uk (Barry I presume) has been very helpful and shows good knowledge of the boxes and stated in his experience, that a complete oil & filter change to the trans, often cures any faults - Just hope he's right on this occasion.
Edited by sparky35uk on Saturday 20th September 18:10
... well first few years anyway depending on mileage. 
Does it go straight into limp home, or does it slip first???
When I first looked at this post, I remembered the fault code P0706, I thought its was range performance/slip, I.E input speed sensor reports say 2000rpm, box knows output shaft speed should be say 3000 rpm, and when they not what they should be logs the fault.
We used to change the box with that code, but back then, jaguar waranty were paying so no worries.
Sorry to hear its not going well.
Have you got the "jaguar" wiring diagram, I got it on PDF somewhere, well take a while to find, but can email you it if it helps.
When I first looked at this post, I remembered the fault code P0706, I thought its was range performance/slip, I.E input speed sensor reports say 2000rpm, box knows output shaft speed should be say 3000 rpm, and when they not what they should be logs the fault.
We used to change the box with that code, but back then, jaguar waranty were paying so no worries.
Sorry to hear its not going well.
Have you got the "jaguar" wiring diagram, I got it on PDF somewhere, well take a while to find, but can email you it if it helps.
Hi, thanks for your reply....yes' i have the wiring diagrams as I have the JTIS cd. The original fault code P0706, seems to have gone (I now have purchased an OBDII scanner) and the code that I'm permantly stuck with is P1722.
The car starts fine, with no 'gearbox fault' on the dash, but will not move untill about 1600 - 1800rpm and imediately register 'gearbox fault', with the resultant code.
Also, reverse seems to not be there untill in fault mode. When the engine runs, and also just running through the gears (at standstill) a slight 'hissing' noise can be heard, particulary in P & N?
A real strange one this......I would love to fix it, but fast running out of options.
The car starts fine, with no 'gearbox fault' on the dash, but will not move untill about 1600 - 1800rpm and imediately register 'gearbox fault', with the resultant code.
Also, reverse seems to not be there untill in fault mode. When the engine runs, and also just running through the gears (at standstill) a slight 'hissing' noise can be heard, particulary in P & N?
A real strange one this......I would love to fix it, but fast running out of options.
Didn't think you were! Yes, it took about 6 litres which is about what came out originally. Did a cold fill which took about 4, then warmed up the box with the engine running, and had someone in the car 'cycling' the gears P,R,N,D, whilst I filled the rest.
Have used the proper oil (Esso LT 71141). Might have a go again tonight to see if it will take any more, but since it is what I got out, I doubt it somehow.
If it is mechanical failure, I find it strange that the car will still drive - even if only in fault mode, or is that because it's what I would call 'direct drive'
I know the box holds 10litres in all, but of course, some gets stuck around the torque converter so about 6 litres seems right, espcially since thats all that came out!
A tough one this....
ps, yes used the correct fill/level plug by the exhaust.
Have used the proper oil (Esso LT 71141). Might have a go again tonight to see if it will take any more, but since it is what I got out, I doubt it somehow.
If it is mechanical failure, I find it strange that the car will still drive - even if only in fault mode, or is that because it's what I would call 'direct drive'
I know the box holds 10litres in all, but of course, some gets stuck around the torque converter so about 6 litres seems right, espcially since thats all that came out!
A tough one this....
ps, yes used the correct fill/level plug by the exhaust.
Edited by sparky35uk on Wednesday 24th September 06:25
Sounds like its full to me, I used to use about 6 litres.
Does sound like a mechanical failier, but its just odd that the fault code now is different to the one before.
The black "cool box" where the ECM and TCM are isnt full of water? I had that before. Had faults stored for all gearbox sensors short to positive and some other random ones, TCM was under water.
Does sound like a mechanical failier, but its just odd that the fault code now is different to the one before.
The black "cool box" where the ECM and TCM are isnt full of water? I had that before. Had faults stored for all gearbox sensors short to positive and some other random ones, TCM was under water.
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