Unfortunately the problem recurred with a vengeance a couple of months ago. By this time time I had pursued all leads offered including replacing coolant temperature sensors. It got to the point where Jaws was pretty much undriveable even when fully warmed up. On the day I booked into the (trans)mission hospital, reverse gear failed entirely.
Upshot was new 'box needed. Lovely replacement unit imported from JATCO and fitted. Unfortunately she stalled again in the same way before I could drive home. So after research and prompting the Transmission Control Unit (TCU) was investigated. Corroded pins were cleaned up and hey presto a big improvement. But still not right. A swap of TCU made no difference so the wiring loom was checked. After stripping it out, checking patiently pin to pin and multiple repairs normality has been restored
(That said I have only had her back a few days)It seems the solenoids in the 'box are controlled by switching them to earth and back as appropriate. Poor insulation, corrosion or broken wires with intermittent contact play havoc with a carefully programmed sequence of changes. I assume that the link to temperature was that once the loom dried out, the 'short' caused by moisture resolved.
So beware. Erratic gear changes might be wiring or TCU related and if not sorted can lead to expensive gearbox failure.
