Gearbox Oddities

[ulfilias]

Hi Del,

Yeah. I've checked / topped up the oil. I did that last week before I went anywhere at distance. To be fair it ran fair with slightly low oil (it took about 400ml over what i'd already put in at an angle)

Since it's quick and easy to play with the TCU's and I have 3 I thought i'd have a look at what happens using the other two for comparison



DG from my dead FL S8, old BG with solenoid fault, New BG


Old BG - Solenoid error


DG - Software not recgonised




New BG, Before Fault


New BG, After Fault

[ulfilias]

Notice that with two of the boxes limp mode seems to be 4th gear. I tried the DG box after the New BG which gives 5th with the idea that maybe it did work at all and would stay in the last gear, but nope it gave 4th too.

Oh and i've made a minor error. The boxes are BL not BG!

[Delboy]

Man that sucks,

I see from your screen shots that input speed matches engine speed which is what i get when i select drive on mine, so would say thats normal behaviour.

Unfortunately mines a different gearbox to yours so even if I logged it through the different gears it wouldn't tell you much.

But i'm puzzled why your input rpm would be 0 when its in limp mode, unless that's how its meant to be???

[ulfilias]

Hi There,

No idea on the 0 RPM in limp mode, though I was probably had my foot on the brake. The rpm sensors are working fine given other readings so i'd ignore.

Last night however saw me loose power in 4th gear and I now have no forwards momentum at all. I've tried the other TCU's this morning and nothing.

Oddly reverse is fine and I ended up reversing a couple of miles back to my factory where I had a spare Smart Car which go me home!

No Idea at all where I go from this ????

[PsYcHe]

have you checked the F125? Could be that the box is foobared though.

[Delboy]

Thinking about it some more its probably meant to be like that on the speed sensor as that input one probably locks up to send power through to the planetary for 4 gear (Limp)

It wouldn't be anything to do with the MAF by any chance as I have read elsewhere that it can screw with the box if its not right.

Might be worth a quick disconnect to try?

[PsYcHe]

It won't hurt at least... If it's just that, you might be lucky enough to save the box in time.

[ulfilias]

Hi There,

For the 10 minutes it too to disconnect and reconnect the MAF sensor, it was worth a shot, but nope. No change to getting any forwards movement.

I doubt it's the F125 switch. I did disconnect it when under the car and actually the engine won't start without it which surprised me. I have no fault on it and under VCDS on measure blocks you can check it's operation as it has a 4 digit binary code (0101 etc) and you can cycle through all of the digits by the various positions on gear stick. This to me would say that it is fully working. Alas.

I am wondering if it is the torque converter, but i'm guessing gearbox rebuild as there is no forwards movement, but it will reverse.

[brasiliangringo]

More documentation

[brasiliangringo]

5HP24 repair manual NOT 5HP24A which i dont have..