Quote:
Originally Posted by Mondaveo
Ah, thank you my man! That changes the interpretation of my graphs and could be a breakthrough. If input sensor = "RPM" then I should see any evidence of the erratic signal on that line, rather than the line for "GISS" as I'd thought. And indeed I do have a squiggly trace for "RPM" in many instances where the gearbox shifted awkwardly. I had attributed that as a result of changing engine load with the clutch dis/engaging but it looks like it could be the evidence I was seeking.
The interesting thing now would be to compare the "RPM" exposed by the TCM with a recording of the actual RPM at the engine ( ECU?). Unfortunately I don't think FORScan allows me to live stream from two different modules at once...
(BTW, I think you mean Bundy's photo?) |
morning gents,
I've been having issues with harsh shifting for a long time and have followed this thread for almost as long. Having some time to spare at the moment I thought I would have a further look into the issue I'm having as it doesn't look like anyone has actually done a repair/fix on this yet, apart from sending to a gearbox specialist or selling the car, neither have I but I believe I have worked a few things out.
I'm getting P0715 basically all the time as well as the harsh shifting and jerking on take off, but have only ever had limited transmission function come up on the dash once.
On a slightly different note, what's everyone's thoughts about the chances of my issue being related to contamination on the GISS sensor?
From the graphs I believe the RPM line in the opening graphs will be coming from the bell housing that then plugs into the
TCM. The GISS is a sensor in the mechatronic unit which can be referred to as the input speed shaft sensor. I'm pretty sure this is the sensor that I'm having problems with as well as Mondaveo had. This is based on the fact that when the car is stopped you can see on the graphs the value for the GISS goes to 0 RPM, meaning that both clutches are off and no drive is going to the gearbox. This is based on graphs I have taken.
Based on the fault code and the GISS sensor being in the mechatronic unit I believe that the reason that Mondaveo was quoted for coolant is that the mechatronic unit can be removed from the gearbox without taking the gearbox out, it does mean draining the coolant, hence the need for coolant on the quote. However the quote I believe shows the wrong sensor. based on the pictures of the part they quoted, this is the RPM sensor on the bell housing. At the moment I haven't tracked down the correct part number for the GISS.
It seems that the GISS sensor only reads input shaft 2. Based on both output shafts being connected to the main diff gear, both input shafts will be turning while either of the clutches or any forward gear is being used as the there's always a second gear selected. I can only assume that when its using a gear on input shaft 1 it works out the correct speed of input shaft 2 based on the gear ratio between the gear in use and the next selected gear.
I have tracked down a series of YouTube videos of the mechatronic unit being removed for a different issue, but it does show how to remove it, however not how to change the GISS sensor. link to the first video is here:
https://www.youtube.com/watch?v=jxCEdxT2_Rk
I've also tracked down a manual for the 6DCT450, I've tried to attach to this post but it didn't work for some reason, but if you want a copy let me know.
It would be interesting to hear peoples thoughts on this.