My '90 Majestic has an occasional problem, especially in very hot weather, with the PARK position in the trans shifter
not working to start the car - Shifter in Park, turn the key to start, start doesn't start. Shift to neutral starts OK.
I remember reading some years back about a micro switch in the "shifter module" becoming troublesome with time and mileage.
The author provided a part number for a replacement micro switch.

Does anyone have any idea?

Thanks,
Roger

 

Hi Roger,

I may be wrong, but I think the microswitch was in the J-Gate on the earlier cars with the hydro-mechanical 4HP22 transmissions, but on the 4.0L cars with the electronically-controlled 4HP24 transmission the Park-Neutral/Start Inhibit switch may be part of the rotary switch on the left side of the gearbox, at least that's the way it looks in the schematics. Check the Electrical Guide to see if it gives the location of the switch on your car:

Jaguar XJ40 Electrical Guide 1990

There may be information about the microswitch in the Jag-Lovers E-Book:

Jag-Lovers XJ40 E-Book

Here's a photo album showning the location of the microswitch on an X300 - it's possibly your car is set up the same way:

Jaguar X300 Not-in-Park Microswitch

Cheers,

Don

 

Don is correct, the start inhibit feature for 1990 is built into the transmission rotary switch, located at the left front of the gearbox. It interrupts the signal to the starter relay.

Does it feel like the shifter is sloppy and could be adjusted? Maybe the linkage is a tad bit off, and that's what's throwing the rotary switch off too?


Otherwise, I think replacing the rotary switch is the next step.




Nick

 

Roger,

To supplement Nick's excellent suggestions, I'm linking to a couple of photo albums below. Sorry the large images still are not back up at Jag-Lovers, but the thumbnails and descriptions may be helpful.

Your cable could very well be stretched, or the end where it connects to the rotary switch lever may be corroded and loose.

Cleaning the electrical connector at the rear of the transmission may help, and it is also possible to clean the rotary switch gold contact pads with a combination of a soft pencil eraser and zero-residue electronic cleaner spray.

ZF 4HP24 Electrical Connector
ZF 4HP24 Rotary Switch

Cheers,

Don

 

Thank you both! You rattled my memory about the rotary switch. I serviced the trans a few months ago so the rotary switch makes sense.
Hopefully the problem will continue to be infrequent until Florida's summer heat lessens and I'll check it out.

Thank you,
Roger