Hello - I just acquired a 1995 XJR that needs some TLC. First issue is that the car sometimes doesn't start unless you 'wiggle' the gear lever? The 'P' light doesn't come on initially when I turn the ignition, but after a wiggle it sometimes does, or if I move it to Neutral, the light comes on. Feels like a sensor/safety switch issue. Suggestions?

 

The rotary switch is on the transmission body on the left side

The contact fingers get dirty inside

The starter relay may be intermittent and a easy swap to try , try the heater pump relay

 

There is a liner switch on the side of the shifter, that is what tells the starter interlock the shifter is in P or N and allows starting. There is a calibration/adjustment procedure in the manual to make sure it is aligned with the shifter position. As you've noticed, it can come out of adjustment, if the P lights up you should be good.

As a note for the archives, this switch is only on the XJR and XJ12 with the GM transmission, The normally aspirated 4.0 shifter/switch with the ZF transmission is different, so the diagram posted above does not apply.

 

Disregarding Lady Penelope's diagram, if referring to the "Transmission linear switch" I believe it is fitted to most X300 models, not just the XJR.
It is clearly shown on the attached page from the Service Manual for the X300 (note ZF top right of page) & is still listed & shown on the parts diagram by Jaguar Classic Parts.
Adustment is described on service manual page.
Part number is LNA6550BA & is applicable to Vin nos 720125 to 812255.
I also note previous forum post by "Fareaster" 26/8/18 which confirms this & I tend to agree.
The other attachment "Gearshift Interlock" may also be of some assistance.

John Herbert
(1996 XJR)

 

This confusion has come up before. I can't remember if any final conclusion has been drawn.

The wiring diagrams show the linear switch for the 3.2, the V12, and the 4.0 supercharged. But not for 4.0 normally aspirated.

The parts catalog mostly agrees except that the linear switch IS shown for the 4.0 normally aspirated but only after VIN 737934.

At any rate, the V12 and supercharged cars, which use the the 4L80E transmission, don't have a rotary switch.

It might be easier to say, "If you have a linear switch, adjust it"

I'll add the the "P" must glow red before the engine will crank. If it glows white, the engine will not crank. At least that's how it was on my XJR....which required adjustment of the linear switch.

Cheers
DD

 

Without looking at the wiring guide too deeply on the 4.0 normally aspirated the linear switch may be for lights only

The 3.2 uses a different version of the ZF 4 speed transmission ( ZF4HP22 vs. 24 ) that does not use electronic controlled shift solenoids but old school fluid logic and fluid pressure

 

You may be onto to something as I have vague memory of it being referred to as a lighting module or some such. It's been some time since I was elbow deep in X300 stuff, having sold mine a few years ago.

Right. But it still needs some form of neutral safety switch (or lighting module?) so the linear switch serves that function?

Cheers
DD

 

Thanks much, very helpful indeed.

 

Thanks all for the guidance. I'm beginning to appreciate the complexity in all of this and the benefit of the knowledge you bring to this forum. Thanks again