Allan,

Thanks for the gentle correction - that's what I get for writing off the top of my head! You are correct about the DM and the only very minor correction I can offer after consulting the caption of the first photo in my album on the Decoder Module is that the DM communicates P/N position to the ECM and TCM rather than BPM. I based my caption on the manual description of the DM's function, which sounds nearly word-for-word the same as yours, so I think we agree!

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Cheers,

Don

 

Don,

Definitely no correction was implied, rather an input to the conversation I'm not sure if the XJ40 arrangement is different but in the X300 the decoder does not appear to communicate with the TCM but does share P/N condition with the ECM and BPM (The BPM handles the cranking control strategy). The TCM speaks directly to the ECM.

The TCM gets the gear position solely from the rotary switch as it can read the 3 digit 'code' the rotary switch outputs.

If you have a copy of the electrical manual, Figs 3.1, 4.1 and 5.1 will illustrate this much better than I am explaining it

The beauty of this forum is that we can share info and experiences about our Jags, often unlocking mysteries that can plague us from time to time

 

If I am reading the service manual procedure correctly, it appears that the adjustment can be made on top instead of having to crawl under the car. This is the plan for tomorrow. Now that I think about it, the shift lever doesn't have any "feel" to it once out of the Park position. No detents felt at all.

 

You can adjust the decoder from under the console but the rotary switch needs to be adjusted from underneath. There is a special tool to help with the alignment but I think you can do it without too, though I've not had the pleasure yet

 

A great big THANKS to all who have offered help and suggestions! Today the XJ6 drove to the gas station under its own power!
This evening I crawled under the car to see if the shift cable was connected, and it was. However, I could shift the transmission by hand with no affect on the shift lever inside the car. I shifted it into Neutral under the car and was rewarded with a red "N" and was able to start the car with the key in a normal manner. I proceeded to disassemble the ski slope and found the shift pin (my nomenclature) projecting from the lever not engaged in the plastic shift dog connected to the shift cable. After correcting that I had the red "P" glowing and the car started with the key. All gears worked as I drove to the gas station and she wound up to red line with no complaints. I haven't tried all accessories; I'm going to just enjoy the ride for a day or so before I start looking for the next task. The XJ6 is alive and well!