Hi and thanks again to all who reached out with helpful advice. After spending some time today trouble shooting we have determined that the problem is in the J shift mechanism. I assume there is a interlock switch that is not quite making contact as it should. If the car is in park, nothing happens when turning the ignition. Yet if the shifter is moved a little down from "P" proper I can get the starter to engage.

Does anyone know the name of the interlock/ module/ switch that lives in the J shifter that I will need to replace?
Again thanks in advance..

 

Probably no replacement needed, only an adjustment of the position of the starter interlock switch. it is on the right side of the J gate, under the trim and wood veneer. Hopefully that will give you the red glowing "P", and problem solved. There are threads about removing the J gate trim and "ski slope" wood trim, search them out, they are very useful.

 

I agree that it probably just needs adjusting. If you are having to move the lever down from P then may need to adjust the rotary switch which is under the car on the drivers side of the transmission. As I recall there is a tool that you can use to properly set the adjustment.

If the issue is the P/N switch then yes it is just below the J-gate so you'll need to remove the ski slope and J-gate cover to get at it.

 

Read your post M.C. Scrabble and immediately ran down to the garage, but no joy. Manipulating the shifter is of no help for me, still no red "P". This morning I will check the pin out Allan suggested. I wonder if there is a way to wire around the P/N switch or if that just causes trouble elsewhere?

 

Thx again everyone. We will be pulling the ski slope and working on it this weekend.
I'll report back with news..

 

Update: Located the starter relay behind the LH headlights. Removed the relay and tested it; it works normally - 12V across terminals 1 and 2 cause terminals 3 and 5 to close. I put a test light across terminals 1 and 2 on the plug in the wiring harness and turned the ignition switch to position III - I expected the light to come on indicating 12V available but that did not happen. I then jumped the terminals 3 and 5 on the plug in the wiring harness and the starter energized. Apparently something is preventing 12V from getting to the starter relay. I was hoping I could avoid tearing into the ski slope etc. but I guess that is next on the list.

 

Knuckles,

Before you go tearing into your ski slope, do the checks I suggested above to the BPM. It's easier to get to and will help narrow things down.

 

Allan,
A little help in locating the BPM would be appreciated. The manual I have shows it in the RH Drive location and says LH Drive is opposite. That puts it near the front passenger kick panel but that is where the Engine Control Module is. I guess the drawing isn't clear enough for me or ???

 

Knuckles,

It's not at the passenger kick panel but rather behind the passenger knee bolster. If your 95 is an early one like mine, just remove the passenger side under scuttle panel (AKA the knee bolster) The BPM is in the middle high up mounted vertically.

I thought I had a pic somewhere but can't find it. If I have a chance tomorrow, I'll take one and post it.

 

The BPM slides straight down after you pull out on the spring pin located on it's front. No tools or big force required!

As Mr. Scrabble has resigned himself to taking apart the ski-slope (it's not difficult at all), you Mr. Knuckles will most likely be doing that too. No red P, no crankie! Yes, you could also bypass that switch to (hopefully) see the red glow of the almighty "P".

 

The BPM slides straight down after you pull out on the spring pin located on it's front. No tools or big force required!

As Mr. Scrabble has resigned himself to taking apart the ski-slope (it's not difficult at all), you Mr. Knuckles, will most likely be doing that too. No red P, no crankie! Yes, you could also bypass that switch to (hopefully) see the red glow of the almighty "P".

 

The BPM slides straight down after you pull out on the spring pin located on it's front. No tools or big force required!

As Mr. Scrabble has resigned himself to taking apart the ski-slope (it's not difficult at all), you Mr. Knuckles, will most likely be doing that too. No red P, no crankie! Yes, you could also bypass that switch to (hopefully) see the red glow of the almighty "P".

Edit: My apologies for the triple post... having trouble with forum response and/or my connection!

 

(At least) one of the cars being discussed in this thread is a 95XJR....can't remember if it belongs to Scrabble or Knuckles or....

Anyhow.....

On the 95 XJR and the X300 V12 (not sure about others) there is a black box on the right side of the shifter assembly known as the "linear switch". If the "P" doesn't glow red, loosen the linear switch screws (a little tricky) so the switch can be adjusted fore-n-aft.

With the gearshift in "P" and the key on simply move the linear switch until the "P" glows red. As with any similar adjustment you move back-n-forth a bit to find the sweet spot, so to speak. Tighten the screws, reassemble console.

There is no rotary switch on the transmission for the XJR/6 or the V12.

Cheers
DD

 

Yep, quite right Doug. I believe McScrabble has the XJR and Knuckles the XJ6. As I understand it, the N/A AJ16 has a rotary switch on the side of the transmission and then uses a decoder (the same linear switch used in XJR) to transmit the gear position.

 

This is from the ZF service manual.

 

For what they're worth, below are links to photos of the rotary switch, decoder module and transmission electrical connector on our '93 XJ40, which has the same ZF 4HP24 electronic transmission as I believe were installed in at least some of the N/A X300s:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

If I'm not mistaken, the X300 BPM is the equivalent of the CPU in our '93, which can be seen in photo number 5 of the album at the link below. I'm sure there are differences in the modules and layout of the X300, but maybe these photos will give Knuckles a general idea until Allan is able to post something:

Welcome to Jag-lovers - Members Photo Viewing Page

Cheers,

Don

 

Ok had a chance to take some quick pics with my phone.

First remove the passenger underscuttle which is below the wood dash panel.



Then remove the heater duct



The BPM is on the left mounted to the Aluminium chassis



Pull the silver knob and then pull the BPM down.


Once detached it looks like this

 

Thanks to Allan's kind assistance I found the BPM and it appears P/N is not functioning correctly as evidenced by pin 20 in the black connector.
Before tackling the ski slope I decided to try feeding the beast some fresh premium fuel and try cranking it by bypassing the starter relay. After several tries with the engine sort of running along with the starter, it caught and ran! Following a cloud of smoke the rough running engine settled into a smooth 700 RPM idle with clear exhaust.
Oh yes, it also proceeded to idle out of the garage! The shifter was in Park but the car was driving off! The wife drove it around the block and brought it back into the garage. We appear to have Drive and nothing else...no Park, Neutral or Reverse. Moving the shift lever seems to have no effect. Is this an adjustment issue or do I have a more serious problem?

 

Knuckles!

Oh man! I'll bet that caused a few anxious moments! I'll spare the jokes about "having white knuckles" or "being a real knuckle biter." :-)

The possible causes that come to mind are a broken cable between the gearshift lever and the rotary switch on the side of the gearbox, the black plastic arm in the rotary switch is broken, or the decoder module is telling the TCM to put the gearbox in Drive even though the gear selector is in Park (did you possibly disturb the decoder module while working on the P/N switch?).

Don

 

Don and Knuckles

Unless I'm mistaken (and I may very well be ), the decoder does not communicate the gear position to the TCM. I believe the decoder's job is to illuminate the appropriate LED on the shifter, report the Park/Neutral position to the ECM and BPM and whether or not cruise control can be engaged.

I believe that the Rotary switch provides the gear position to the TCM. I completely agree that the cable from the shifter may be broken or more likely, the linkage loose or out of adjustment.

It can definitely be adjusted, here is the procedure from the service manual. If you haven't already downloaded the manual from the sticky section, I would urge you to do so. It's free and invaluable