S1 auto kickdown

XJ
41

Since my system is likely(!?) compromised using Window7, I don’t really know how the new set-up is meant to work. In the older set-up I got the ‘quote’ window at the lower screen - allowing to read the original post at the upper half.

Later, I got the reply text on the left half of the screen - and a b… repeat of what I wrote on the right side. Still with original post of top - fair enough, but an incomprehensible misuse of screen space.

Now, using ‘quote’, the original post is invisible - and and repeat ‘quotes’ impossible. And half the screen is still just used for a repeat of what I write! There may of course be something ‘useful’ or even ‘necessary’, or whatever, for other parts of the Jag-lovers site forcing the change - but it escapes me…

To Kevin and others with the same issues; I have ‘solved’ the repeat ‘quote’ while keeping the original post. I use ‘reply’, then use ‘O’ (quote entire post), extreme left on the bar. then I write my replies in succession - and delete the parts of the original message not relevant. And hit ‘send’…

For all I know; this is what the geeks intend - but using half the screen as a default to repeat what I write is completely incomprehensible. Though, of course - you can set full screen by selection…

As an aside; being a procrastinator here as with my cars; this issue finally pushed me to buy a lap-top with Windows 11. I use Windows 7 as I have valued programs that cannot be transferred to later Windows or other systems - hence the procrastination as 7 still (mostly) works satisfactorily.

And during set-up the damned thing froze halfway through the set-up. And knowing nothing about lap-tops; I don’t know how to unfreeze it. On my desktop, as a last desperate resort, I could just unplug it - but you cannot easily ‘unpower’ a lap-top to bring it to its senses - an expert is called in…:slight_smile:

( Advice on lap-tops not unwelcomed - though the forum is hardly the place)

Frank
xj6 85 Sov Europe (UK/NZ)

42

It shouldn’t be a windows issue, did you try another browser?

If you hold the power button for more than 10 seconds laptops usually crash as if you pulled the plug. During update or installation processes this can cause issues. The last windows laptop I tried to help set up (this spring) was not just a terrible experience, but pure horror; I‘m now staying away from these. Can’t be bothered to waste half a day on something so annoying and complicated. I also had to have Windows for a CAD program a few years ago and got rid of that immediately afterwards. What I‘m saying is don’t feel bad if it seems incredibly complicated to set up. Do they have any customer service where you bought it?

You can possibly do something else by the way, put two browser windows next to each other in splitscreen and copy the quotes from one window, paste it in the other?

43

The “click” is the sound of the solenoid pin retracting - so it is working. If it was a direct short to earth in the solenoid I would have thought it would not click at all. Is the 7.9 ohms from a spec somewhere or did you measure it? Was your 20A reading using a separate direct +ve feed form the battery or using the car kickdown switch wiring?

Frankie

44

This from SNGB looks like it might be correct for the 12A and 12J

Frankie

45

Hi Frankie,
7.9 ohms was the measured resistance to earth, and the current reading was with meter in series with a direct connection to the battery, no switch involved. I do question the accuracy of that as I think with 20+ amps flowing through it, my flylead would have started heating up. It didn’t. SNGB listing shows to special order, presumably no longer available.

46

I agree. Add a 5A or 10A fuse to the test circuit from the battery and try again - does the fuse blow? Or source another meter. If I have time tomorrow I’ll run the same tests for resistance and current on mine and let you know.

Frankie

47

You just have to floor it. It’s either on or off on my car once the solenoid operates it kicks down. Having said that the hydraulics have usually sensed the change in demand and do the job ahead of the solenoid.

48

Indeed, David - he is coming tomorrow…:slight_smile:

As it froze during initial set-up, the ‘general’ rules probably do not apply…?

Frank
xj6 85 Sov Europe (UK/NZ)

49

If that was to earth (the connector at the side of the casing), from the point you applied battery voltage - all other wires disconnected, Kevin; you should read some 1,5A…

If your ammeter peaked; it connects to earth somewhere - not through the resistance you measured…

Frank
xj6 85 Sov Europe (UK/NZ)

50

Yes, current reading was battery- meter on 20A amps scale- connector on side on side of trans- solenoid- earth. Digital VOM . Rarely, if ever, previously used current reading, but clearly not correct. Tech said he tested the solenoid on the bench, but I don’t know if that included having the rod inserted to see if it actually pushed the vave body rod into the body to open the valve. My, admitedly limited, experience suggests that solenoids either work or don’t; they go open circuit and don’t operate, or go short circuit ( never seen that) and blow fuses. All evidence before me suggests the solenoid is working, switch operates, solenoid clicks, which is why I have difficulty believing it is at fault. But what else? This is like a previous thread about ignition; I don’t like throwing parts at a fault until it just disappears, especially as the parts are expensive and costly to fit, unlike the ignition issue, which, arguably results in improved performance regardless of whether or not the actual problem is identified.

51

Tested mine this morning. Resistance between solenoid terminal and gearbox casing = 9.0 ohms; current draw using a fly lead direct from battery = 1.8A. Suggest you re-test using a different meter of known accuracy before further speculation as to cause.

Frankie

52

Thanks for your input, appreciate the effort. Will do.
Cheers

53

Hi Kevin, as I mentioned the kickdown solenoid In a Model 12 doesn’t actually move the internal valve/rod. It merely opens to create a pressure differential and the valve/rod that controls kickdown moves toward the solenoid against a spring in front of the solenoid - on it’s own - due to pressure behind it. The kickdown solenoid is just a valve - it doesn’t push or pull anything external.

If you wanna take it out and test it further you can do it by dropping the pan, turning the solenoid to clear the flat and pulling. A waste of some fluid of course but probably your next step. There is a ball valve in the nose that needs to be free to open when energized to open the valve. It also has to be properly closed when off to stop the pressure bleed.

If you pull the solenoid, make sure it’s correctly locked in before removing to verify that tiny rod/pin I mentioned earlier that retains the solenoid is there and holding it in place. If it’s not locked in properly, or the O-ring sealing it is perished or out of place it will always bleed pressure and not kick down.

The vacuum modulator is also part of this circuit but I think you mentioned you replaced it.

54

Good, clear advice; thanks Mike. The modulator was replaced, and the O ring around the solenoid; it was so hard the tech originally thought that was the issue. Sounds like you are familiar with these; have you ever heard of solenoid failure, especially when you can still hear it operating? I would have go at this myself, but the valve body also needs removal, and I can see that turning to custard as I don’t have a hoist.
Thanks for the input.

55

If you really think it’s worth it (nothing better to do?) put on goggles, wrap your head with saran wrap and crawl under… I‘ve done it more than once and every time I regret it a bit more. Removing the valve body itself isn’t difficult and as long as everything stays clean and you know what you’re doing, nothing can go wrong.

56

Kevin, I am pretty familiar with BW Model 12’s in Jags - I actually have 3 of them from S1 XJ’s on the floor of my shop right now. No, I haven’t encountered a kickdown solenoid not working when you could hear it clicking but that doesn’t mean it isn’t possible. It’s just a ball valve so there’s not alot going on inside it.

I’m about 90% sure you can remove the solenoid without taking out the valve body - it’s been a few years since I’ve worked on one with it still in the car (usually take 'em out these days) but the last time I did I replaced that o-ring on the solenoid and IIRC I did not remove the valve body. Turn and pull as I’ve described - I do remember it being a bit ‘fidldy’ however. But the hardest part of it is the mess. Removing the valve body intact is not difficult at all - you just gotta take your time and pay attention to how everything goes together. There are some tubes to worry about and engaging the manual-shift plunger but none of it is super complicated.

You can also make draining easier by lifting the back of the car and then loosening the big nut that holds the dipstick tube to the pan. Then let it drain. When you do that removing the pan is much less messy.

The kickdown system works via internal pressure so if the solenoid is working there is something that is disturbing the hydraulic balancing act going on in the transmission. An incorrectly adjusted vacuum modulator may also create an issue - they are extremely important to the function of this transmission. Other than the kickdown issue, does the transmission function properly?

57

Yes 'box shifts smoothly and correctly. The car hasn’t been driven since 2013, and only done 10-15 miles since I got it running again, but only in short runs of perhaps less than 2 miles at a time. Is this something that might come right with a bit of use; perhaps when the 'box gets warm, if the valve in the solenoid is stuck?

58

There is no plan, therefore nothing can go wrong. :smiley:

59

If you do remove the pan take it to a good welding shop and get them to cut and weld a drain plug in at the lowest point. I did that on my first fluid change - makes life so much easier the next time.

Frankie

60

What we need is a function/layout plan of the BW12, Kevin - like on the BW66. Others have presented various function descriptions - but I still don’t know if it is a separate kick-down valve (I doubt it).

On the BW66 there is no kick-down function as such. The downshift cable mechanically moves the shift cam according to pedal position - and operates the downshift valve, which controls all shifting. Ie the cam shape will cause downshift if the other inputs to the box allows it…

I see no mention of adjustments of a mechanical connection between throttle pedal and the box on the BW12 - so presumable there is none? Ie, the vacuum modulator controls shifting according to manifold vacuum together with other box inputs - which limits downshift with general pedal movement. And the kick-down switch is added for extra driver control - which means an extra valve?

In which case the valve’s relation to the hydraulics may be the problem; blockage, or indeed a faulty valve - or the suspected solenoid…?

The mere fact that the kick-down function doesn’t work according to you. Which, if true, is certainly a fault - but what the fault is is a different matter.

Which is not much help…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)