Problems with speedo and Overdrive light

[carluk66]

I need any advice on a problem with my Hilux Surf 3L auto turbo diesel ( 1994 model). The speedometer doesn't work while first setting on on a journey but suddenly starts working then on other occasions it starts off working then stops plus the Overdrive light on the dash keeps flashing intermitently. I do believe it's an electrical fault but are both related ? Any advice on fixing these problems wiil be much appreciated !

thanks in advance

Carl

[TonyN]

I don't think they are related, I've seen other trucks with duff speedo's and its not set the tranny fault light (the flashing OD light) off, but may be wrong.

First up I'd check all the plugs on the gearbox, and the speed sender unit on the back of the transfer case. You can get the fault codes for the gearbox in the same way as the engine, Do a quick search for it, its been covered before.

The gearbox may just need a good flush, if its sludgy, things won''t select properly.

The speedo will have been removed to do the MPH conversion, could just be not put back properly, I'd check the facia unit for loose wires and plugs.