...another Trans Prog Fail & P0705 2005 4.4 V8 Auto L322

Hi Guys, as a recent member - but frequent reader of your forum, I very much appreciate all your advice and experience shared. I too have the Trans Prog Fail message, accompanied by P0705 which is persistent to the extent that I can no longer move the car. If “P” doesn’t appear on the dash on start up, it disappears as soon as touch the shift. It did once manage to move when starting up in neutral. Although i dont have much auto electronic/engineering experience I am an engineer so ought to be able to diagnose/trace faults/follow Bembers superb instructions etc. I’m hampered by working away in Netherlands, and while I brought a selection of tools - I dont quite have everything I would want, and certainly no ramps. I guess I thought the easiest way to test the switch continuity would be at the ECU plugs, but I find my meter prongs too fat to be useful. So onto the harness plug - yes I can just about reach it, but couldn’t separate the two halves - can anyone tell me (as I couldn’t see) if there is a tab to press, or need a small screw driver to pop in and release? So on to the switch for a visual on internals - now I’m not the skinniest of chaps so getting underneath with enough elbow room to work with is a challenge but cable off, cover plate off and switch released from gearbox - I cant appear to slide the switch off the splined shaft - can anyone tell me if there is a circlip holding it on inside the switch? Anyway snow here too today, so I guess I wont be under it again tonight... Thanks in advance for your tips on the plug release and possibility of circlip inside the switch. Will keep you posted as to results - success or otherwise

This part of the connector stays attached to the metal bracket bolted to the top of the bellhousing



so you will need to unbolt the bracket to access the pins for continuity testing. The half of the connector that is part of the vehicle wiring loom (shown in grey in the diagram below) twists off i.e. bayonet fitting



Assuming that you’ve removed the selector lever and the two bolts, the plastic wiper is a tight fit on the selector shaft spline which sometimes (through corrosion) makes it reluctant to slide off the spline







There’s no circlip holding it to the shaft, you just need to get something flat between the switch and the casing to lever it gently along.

Phil

Awesome - thanks Phil. Great images and photos - I’ll be adding to my overseas tools collection and sweeping the snow away to carry on tonight!

Brave chap if you didn't use axle stands...?

I didn’t jack - just crawled in under!

WightinNL said:

I didn’t jack - just crawled in under!

Click to expand...

Whilst unlikely that the air suspension would suddenly collapse, it's enough of a worry for me never to risk it.

I'd at least have a jack/stand on one side.

I dont have the air suspension any more, but a good reminder for those that do

So thanks to Bembles detailed post in another thread on the inhibitor switch- and an investment in a new Fluke with decent prongs, at the ECU plugs I find no continuity across +ve and L1 and L4 when there should be in Park - only on L3. I didn’t try in R, N or D with two faults found already as battery off so cant shift anyway. So I conclude a failed inhibitor switch - I’ve serviced similar potentiometers with wipers in the marine industry, but only as a stop gap if no spare available. Does anyone have any success in bring these back to life before I pick up the phone and commit to £500 plus VAT? Thanks again!

Update time - and its good news, a little longer than expected but only due to my holiday - new potentiometer arrived in the post from British Parts (Geniune LR component) and a little fiddling later its bolted on and plugged in. Rest of the engine bay components back in place and a tentative turn of the key only to breath a huge sign of relief... Everything good, no faults or beeps or messages, drive around the car park selecting all transmission options successfully, followed by a 50 mile round trip on a sunny evening - all good so far. Thanks so much Phil for your excellent instructions and advice - I’m on the road again, and following this little hiccup, the old girl is going to get some well deserved TLC!