456 Gearbox issues

Good Afternoon,
I'm after a bit of technical assistance with my poor 456 Automatic transmission.
The car has been in the workshop due to the gearbox warning light illuminating at 60-70mph even though the car drives perfect, the light then goes out for a period of time and then back on when changing down etc.
:The garage suspected the Tcu, so that was sent away for testing and when refitted the fault is still apparent.
:They then changed the speed sensor and lock up solenoid and since then the warning light is constantly illuminated, will only drive in one gear and is harsh when selecting between first and reverse and the speedo isnt working anymore.
:The Sd1 will not communicate with the gearbox anymore.
Can anyone help. Does anyone have any information on the Ricardo gearbox, TCU pinout etc.

Many Thanks

 

Put the original speed sensor back in and see if the new faults rectify.

 

Hi jeeves,

The 456 autobox is based on a GM unit a 4T80E, transverse unit, used I think on all of the GM big bodies FWD Cadillac, Buick, Oldsmobile, and some trucks. It was chosen by Ferrari since no other autoboxes of the time could handle the prodigious torque of the V12.

It was modified and some beefing up of the casement, by Ricardo to an in-line unit for Ferrari.

I rebuilt my unit after it exhibited the same symptoms you are encountering, with some slippage during shifting. I have not touched the Trans axle/differential. Just replaced the fluid, since the old fluid was clear.

All the components were purchased locally Rock Auto, O'Reillys, etc. using GM parts...torque converter, clutch packs, frictions, discs, spacer components, etc. Replaced lower solenoids A & B, which are easy to reach from under the tranny. The side cover solenoid is more difficult, requiring removal of the rear bumper to access.

The most difficult task of all, was the separation of the torque tube and drive shaft components. Getting into the tranny and replacing components was straight forward.

I hope this is some help.

Let me know if you have any other questions.

Dennis