Friends
After completing a lot of work on the motor getting things correct I have noticed a definite problem with the gearbox, as stated on prior posts I will be going to a 5 speed manual but do not have time at present to this so I need the the old TH400 working.
The drama is that the kickback works fine, put your foot down and it kicks down but doesn't want to kick-up after that, it just holds that gear till you back off then kicks up. this is very annoying as it it will sit in 1st or 2nd and stay at 6-7000 rpm without moving until you depress the accelerator than it changes. I personally have had nothing to do with nor worked on any automatic cars, this is my first one and more than likely my last, where do I start looking? Is there a vacuum switch or is it cable driven? i can't see it being the clutches/bands in the box as it only has 130k klm on the clock.
any thoughts

 

To clarify, this occurs only during kickdown? That is, under light/moderate throttle the transmission upshfits normally?

On the old 400s the most common culprit for 'no upshift' condition is a dead vacuum modulator....or the vacuum hose to the module is disconnected/broken/leaking. In my experience, though, this causes a problem at any throttle setting, not just during kickdown. Still, it merits investigation.

After that I'm inclined to suspect the governor, or a governor-related fault.

Cheers
DD

 

answers Yes and Yes only on light throttle.
I think you may have knuckled it down for me Doug, I had a sneaking suspicion about the kick-down switch but I was not at all clear how the XJS was setup.
When get a chance not for a while now Ill put her up on the hoist and chase the hose up to the motor, if the hose is Ok I look at the switch itself.
Thanks again!