Hello my learned Jaguar Forums friends.

1997 Jaguar XK8. I I can't make the P0706 fault go away. I have tried all I can - checked switches, replaced rotary switch, reset battery & computers. As soon as I shift into D from P car goes into limp home mode.

I know now the middle switch of the J gate is the neutral safety switch. When depressed by shift shaft, makes a ground to the TCM.

Could anyone one tell me what I might expect if I unplug the NSS, besides keeping me from starting the engine while in N?

Any prior experience with this is greatly appreciated.

Very respectfully, Bob G

 

Have you checked the D to 4 microswitch as well. I seem to remember a post / thread where a problem with this also threw up a P0706 code.

 

Hello David. Maybe. With the j-gate removed, I see three connectors and three micro switches. The forwardmost I think is the P switch. The middle appears to be the NSS. Is the third switch, rearmost, the D4 switch?

When car is started in P, moving selector to D triggers the transmission fault. If i start in N, i can select D without triggering the fault.

Can you share with me how to test the D4 switch? Is it normally open or normally closed?

Thank you for your help David.

Very respectfully, Bob G

 

May not be your problem, and I'm not totally sure of my facts but I guess it is easy to check.
I think it is this switch is in the top of the J gate mechanism - you can see it in this picture :- is operates as the gear-shift lever moves across the bottom of the J Gate. I just remember reading somewhere that a similar problem to yours was caused by this switch breaking or coming loose. Worth a quick look.
Cheers,
David.

 

Thank you David. I have had the J gate top removed earlier this week. I also disassembled it to super glue the cracks in the surface cover, unfortunate but common on all three of my XKs. The switch was bright and shiny, and freely activated when its ball extension engaged the semicircular boss mechanism. I also noticed a LOT OF WEAR at the location the gear shift extends through this mechanism. Very sloppy. Perhaps? Another plan of attack for Sunday (it is early morning here). I'll let you know what happens next.

Very respectfully, Bob G.

 

Hello David. Now Sunday about noon here. Completely removed J-Gate cover, including wiring connectors. Disassembled. Micro switch OK. Checked resistance OK. Found one of two tabs where tab connects to plastic boss was not secure. Removed, slightly bent, and replaced. Seems more secure, however, function is same regarding resistance. Although not related, while in there I was unhappy with most of brush lashes missing where shift shaft penetrates. Wife provided fake eyelashes which easily glued in place. 12-pin connector that connects directly to circuit board is suspect. The female 14-pin connector (white) has an ink "X" on it. Unsure why. Next step to check wiring-connector to board. Label on board shows X100 J-gate, and partial P/N B03632-1.

 

Hello David. Approaching 4pm. I wish I could stop and enjoy afternoon tea.

Everything back together. No joy. Here is what I found.

Start car in P. Move selector to R. OK. Move selector to N. OK. Move selector to D. Immediate Transmission Fault.

Start car in N. Move selector to R. OK. Move selector back to N. OK. Move selector to D. Immediate Transmission Fault.

Consistent, repeatable. Frustrating.

Clearly the fault is triggered by selecting D.

I have checked all components of the J-Gate - micro switches, wiring, mounting security, you name it. Oh yes - I forgot to mention that I also replaced the TCM with a Jaguar new one.

Do you (or anyone else out there) have any idea what else could be a contributor to this? All suggestions are cheerfully accepted.

Very respectfully, Bob G.

 

Have you tried adjusting the gearshift lever cable to ensure the lever is in true PRND positions?

 

Hello Truck Graphics. No I have not tried that (yet).

I am looking at the gear selection area with the plastic things removed.

To the immediate left of the NSS, I see a slotted screw with what appears to be a small diameter steel cable wrapped around it. The wire is also worn, some threads broken, where it disappears through a notched boss perhaps 1/2 in away (rearward). Is this the gearshift level cable?

If so, it is worth a try. Which way (cw, or ccw)?

If not, where is the gearshift lever cable located?

Very respectfully, Bob G.

 

Have a look at this :

http://www.jagrepair.com/images/TSB/307-01-1.pdf

 

Hello David. My oh my you are up late this evening. Thank you for sending the adjustment procedure, not part of the workshop manual. It looks straightforward enough. Without a suitable lift, steps 1, 7, and 11 are a challenge. I could probably use the tire jack to raise the car off the ground, but am unsure if that is enough to reach the transmission lever and make the adjustments.

Before risking life and limb, I though I would first try Truck Graphics suggestion.

He suggested adjusting the gearshift lever cable, near the Neutral Safety Switch. Upon examination, it appears the cable has frayed to the point where several of the cable threads have broken. I am unsure if that happened first, allowing the cable to stretch, or the cable stretched, breaking some of the threads. In either case, I plan to try that adjustment first thing in the morning. It gets too hot, humid, and buggy here in the late afternoon (Florida near Tampa).

I have done everything possible with the J-Gate, micro switches, wiring, and even repaired the brushes/ The cable adjustment makes sense, either on top by the J-Gate enclosure, or underneath by the transmission.

Since the problem just started a few weeks ago (no prior history), the cable make sense. I hope you are right, that a stretched 20-year old cable would cause the P0706 fault.

Things always look better in the morning.

Very respectfully, Bob G.

 

Whatever you do, do not use your tire jack to get at the transmission lever under the car. Use jack stands or ramps! That lever is really up there and you are going to have to push and pull on it. (I know that's not much of a technical description.) When I adjusted the transmission lever on my '97 Coupe, I had to remove a section of the exhaust system to get to it properly. However, another member of the forum recently said he (or she?) was able to get at the lever fairly easily, so maybe I did it wrong? Anyway, my advice is to first noodle around with the cable on top, by releasing the large lock nuts that hold the cable in place. I attached a photo of the hard cable/attachment on the topside of my car (since it is exposed for the time being.) Perhaps your 'vert allows easier access to the cable underneath. Either way - working on top or bottom - be safe.


(PS....I now see the Bulletin has illustrations....so uh...enjoy the photo? erm..)

 

Hello Truck Graphics. Thank you for the photo and thoughtful concerns.

Your help and that of David, from Devon, UK are superb and very much appreciated.

I plan to try first from the top. If not successful, I will make arrangements for a local garage to use their lift, or their services, during the coming week. Of course I will have to drive the car in 'limp home mode' to get there.

I can't wait until morning.

Very respectfully, Bob G.

 

Hello Truck Graphics in Maryland.

Tomorrow (Wednesday) I plan to work on the car. We had family over Monday and today I am recovering from the visit and cleaning up the mess.

Finally looked at the car and found the cable sheath lock nuts just like your photo. This was more helpful that the sketch in the Technical Bulletin.

Since my car consistently fails whenever I shift from N to D, make small adjustments and test after each. (I'm scared to do this).

Please tell me if you know, do I need to increase or decrease the length of the selector cable end that extends out from the cable sheath?

I ask because I do not want to move things to a position that causes more challenge in starting the car, or making it immobile in both directions (N to D AND N to R).

I am thinking one full revolution in advance of testing. Does this sound reasonable?

Very respectfully, Bob G.

 

One turn of the lock nut either way seems prudent...I think the best approach would be to first observe the shift lever as you pull it through from PRND. Does it reach all the way to P? To the D? (Observe R and N as well.) It it is short of the P, loosening the nut at rear and tightening the front will push the lever forward. (If not, go the other way.). Don't hold me to this, but it seems you don't have to be super - accurate in your adjustment. I say this because my adjustments worked and I wasn't terribly scientific in my approach, though I did mess around with the adjustments quite a bit. Your approach of making small adjustments and then testing will be fine.

 

Wow, that was a fast reply. Sorry to sound like such a pu_sy, but I once had a bad experience making adjustments and would up towing the car and a very large repair bill (ouch). Now in my 70s, caution is the way to go.

I'll try it exactly as you suggest. The shift easily reaches into P and D, but I'm guessing (I hate to say assuming) that it still thinks it is partially in N, which is why it throws the P0706 fault. Since I have to push the cable into the sheath to achieve D, I will start by tightening the lock nuts forward of their current position. I have about a 1/2 inch of threads forward, and about 1/4 inch of threads rearward.

When I first bought the car, the prior owner said that he replaced an expensive switch on the transmission. Now that I am so much more educated, I can only guess it was the rotary selector switch (expensive), and he did not properly complete the adjustments following replacement. The car seemed to work fine for about 4 months, so it is probably right on the edge of a working position. We'll see tomorrow.

Thank you again for all your help.

Very respectfully, Bob G.

 

Hello David from Devon and Truck Graphics from Maryland.

the predicted track for the eye wall of Hurricane Irma was forecast to pass directly over our home 40 miles SE of Tampa. It did. We had to evacuate, leaving all possessions behind. Our Chevy Tahoe took us to AL, MS, AL, then TN, KY, OH and now at family home in MI.

Had to delay work on shift adjustment.

Planning return urn next week to clean up house debris and resume work on XK8, assuming we have electricity restored.

Just st wanted you to know your help is appreciated and not being ignored.

More when everything returns to normal.

 

I think you have more urgent issues to deal with than the XK8. Thanks for the update and whatever the problems you need to sort out, sounds like you and your family are all safe and sound which is rather more important than a couple of fault codes !!

 

This should help.

Link http://www.jagrepair.com/images/TSB/307-01-1.pdf

 

I'm glad to hear you and your family are well ! Enjoy continuing safe travels and we'll be here to resume sharing tales of Jaguar XK8 ownership when you return.