I’m hoping to get some words of wisdom from you guys before
I talk to my Jag mechanic again as I’m ready to shoot my
mechanic, my Jag or myself! Any help would be great.
My 95 XJ12 has now been in the shop several times with the
same transmission problem with no end in sight.
The background is that the GM 4L80E transmission keeps going
into limp home mode. According to my in dependant Jag
mechanic the cause of this is that the rear speed sensor
needs replacement as it has gone bad and is sending data out
Jaguar kept sending my mechanic a speed sensor which doesn’t
fit. It fits the front sensor location but not the rear. All
the documentation from Jaguar and GM I have looked at states
that the same part fits both the front and the rear but my
mechanic is telling me differently. He went as far as to
send the old rear sensor to Jaguar who could not identify it
or supply a replacement. They suggested contacting GM.
My mechanic gave up and suggested I find one ‘‘online’’. I
recently ordered a standard GM 4L80E speed sensor and took
it to him. He put it back up on the ramp tried to fit it and
So I am at a loss. I am thinking that either…
My mechanic is an idiot and it does fit. He swears that
without ‘‘drilling a bigger hole in the transmission it won’t
fit!’’ and he is a Jag mechanic with many years experience.
Jaguar altered the transmission in this area and used a
different design but even their own documentation says that
this isn’t so as far as I can see and why would they make a
modification like that?
The previous owner of the car installed a different
transmission. Is this even possible? Why would anyone do
that? Surely it would be more expensive than a simple
replacement? How would they even get it to ‘‘talk’’ to the
transmission computer that until this fault worked perfectly
including the sport mode setting! I understand that the
earlier transmission only had one speed sensor. Could they
have done some kind of engine/transmission swap?
Right now the only idea I have is to take it to a dealership
and leave it with them until they fix it no matter how long
it takes them to work it out or how much it costs.
So I am at a complete loss. This is my daily driver and I
really need a solution. Can anyone help me?
Any advice would be great.
Thanks in advance,
P.S. I am going to cross post this to the V12 and XJ40
forums as I understand that this same engine/transmission
pairing was used in the last XJ40 V12’s. I hope this is OK
but I am desperate!–
95 XJ12 - 86k miles
Brit in Washington DC, United States
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