480 on board computer

I have rcently purchased a 480 2ltr GT and am finding that there is a 50/50 chance of the on board computer coming on. If the computer does not come on then the abs light will come on after about 5 mins though the brakes do not seem to be affected at all. How can I correct this bearing in mind I am not the greatest car mechanic in the world?

I don't know if this will help but when I bought my 480 Turbo you could hardly read the computer display (bulb had blown....easy repair) and the Speedo intermittently worked which meant the half of the computers functions did not work.

But this is how I repaired the Speedo, It seems the 480's suffer from dry joints on the printed circuit boards causing a whole host of different problems, one of them being the one you have described.

I hope your patient because this repair takes at least 3 hours !.

Remove the black console surround the speedometer housing
Unplug the information centre ribbon cable from the multi position switch
Carefully remove the speedometer housing as far as it will go.
Remove the green and grey connectors at the rear of the housing. (These are extremely tight and it’s
Very hard not to pull the cables themselves).
Remove the speedometer and place on a table.
Remember to earth yourself or touch something metal to reduce the risk of static !
Remove the white plastic ribbon cable holder (via three screws)
Careful remove the P.C.B from the speedometer by pulling it off the connector pins (this is all that holds it on)
Remove the outer casing screws (these are the hexagon ones around the edge of the housing ((8)
I think).
Remove the speedometer window
Remove the small Blue ribbon cable that connects the speedometer unit to the PCB from the rear of the speedometer housing.
Remove the speedometer itself (Aarrrhhh be careful this looks extremely delicate)

Finally …. You should be able to see soldered connections that connect the green multiplug socket to the PCB (where the wiring harnessed plugs into) . Every connection needs to be re-soldered (remember not to touch the connectors with the iron for to long, as the PCB does not look like it was manufactured very well and some connections look very fragile!.

This is where I think the fault lies… I moved the wiring harness (on a road test) and the speedometer worked, I think there’s a dry joint somewhere in those connections.

Also re-solder all connections on the speedometer unit itself; you will have to remove one of the circuit boards to do this (via two screws).

Finally it can all be reassembled and plugged back in ….. then shout ‘IT WORKS’ …..(hopefully !)
It was very strange because not only did I get the speedometer working my Fuel Range has changed, when I filled up I had 200 miles on my range. After the repair I have 300 ????…….

Anyway if you have any problems (which you won’t !) please let me know, even better tell me the repair has worked on your 480.

Regards

Nigel

As a fellow 480GT owner, I would urge that you appraoch a main dealer with this problem. OK it is not as cheap as DIY or "independents", but they do have the diagnostic equipment, which can save hours, and time is money! I use a main dealer for all jobs on my GT, and on a 2 litre 480ES, and don't regret the expense for what is/are a fine car(s). The work is also guaranteed don't forget.

Happy GTing!

Quentin Lucas