I have recently acquired a 1992 xjs with a 5.3 v-12. It has been out in the weather for 2 years. It had a ff13 code so I replaced the cap and rotor. The rotor had blown out the back and was only running on 1 bank. this cleared the ff13 code and a ff17 code was next. I reset the throttle pot and cleared that code. now the trans doesn't want to shift. in drive when you floor the throttle it will take off but not shift and when you lit off it goes into neutral. If the gear selector is between 1st and 2nd it will shift up to 2nd. Before the ff13 code came in it worked properly. I have changed the fluid and filter. the dipstick says th400 but the trans is a th700 or a 4L60. The headlights and front flashers also are blinking. this problem just appeared. Any thoughts will be appreciated. Thanks

 

Has the gearbox been changed? The factory fitted gearbox was the TH400 not the 700.
If it does in fact have a TH700 fitted with a TH400 dipstick your problem may be fluid level related.

 

Yep Baxtor is right.

Is your trans a 4L60e or a 700R4

I have a 4L60e behind my V12 and the TH400 dipstick is different and would have sat deeper in the 4L60 case meaning when the dip stick said the trans was full it would not have had enough oil.

The full HOT level on dip stick needs to be at the TOP of the pan.

The top dipstick is the original one from the 4L60 bottom TH400



This is where the HOT FULL lines up on the from the 4L60