Interesting Sillyspeed Problem
Well, I've come across a new selespeed problem (on a JTS 156) I haven't encountered before, and its really got me scratching my head (and I've come out from lurking in the corners of the forum reading with interest various peoples approaches to various fixes)....
Basically, it works fine for the most part - Alfadiag shows hydraulic pressure fine, not dropping like a dodgy accumulator. Two gear selections before the pump kicks in (or can get 4 out of it with full pressure and pump disconnected).
HOWEVER - if you sit there in the workshop going through the gears (engine off), it starts to slow down on the changes after about 15 changes, almost like the pump isn't delivering enough pressure, and gets to a point where it won't change gear anymore. Okay, so you'd think its too low on pressure, pump is running, no worries. Here is the kicker though - the pump cuts out, Alfadiag shows 50bar of pressure, and you try to change gear.... Won't even try it, just beeps at you and sits there. About 2 or 3 seconds (or a little longer if you've been really giving it a hard time making it play up) later, it starts to select gears again, until a couple of changes later it stops again, waits till the pumps been off for a second or two, then away it goes again. No fault codes, no flashing selespeed light on the dash, just a beep to tell you it can't be bothered.
The bizarre thing about it is that it doesn't even TRY to select gear while its playing up, just beeps as soon as you hit the selector, which kind of has me thinking its software/sensor related . Its almost like the ECU is programmed to give the pump some relief time before it lets you start playing with the gears. Hydraulic pressure is showing 50bar at the time, so its not refusing to go into gear for that reason (also pressure doesn't dip at when you hit selector, so definitely not even trying). Walk away for a minute, come back and start going through the gears, works fine to start with, then slows down again after a number of changes until it gets to the same point.
I don't think its an issue with the filter in front of the accumulator, as the hydraulic pressure is measured on the actuator itself (as far as I know), so it should at least TRY to select gears, then fail and beep. Clutch position at the time of playing up is the same as when it works perfectly at the start, and gear position indicator seems to correlate to the gear its in fine. So that me rules out two sensors (clutch position and pressure), and I can't see the selector position sensors causing this issue as it will work fine if you let it catch up to itself, and it will just play up in whichever gear it happens to be in at the time (not the same gear all the time).
So basically, I'm wondering if anyone else has played this game, or has any thoughts, because I've thunk myself into a merry-go-round, and my own (often fallible) logic won't let me go anywhere else with this one....
Last edited by EvilGTV; 14-04-09 at 09:53.