Toyota Repair: Toyota Cressida, speedometer cable, toyota repair

Question
My husband's work car is a 1986 Toyota Cressida, 4 door 6 cyl. The speedometer stopped working, and the engine light came on and so did the overdrive light...he read in the book to take it to a Toyota repair it was the computer...well, it's old..but good...what could possibly cause this...oil is good, transmission fluid good, no leaks, water good...he takes very good care of it...help please...we need it.  Thanks...

Answer
I don't too much information available anymore for this model but I beleive that the speedometer is driven by the speedometer cable that is attached to the transmission at the, if I remember correctly it uses a two piece cable, there is a short cable housing coming from the transmission which connects to the cable going to the speedometer, the speedometer cable is the first place to look for the problem, it may be broken inside the short connection or in the main cable, when the speedo stops working it will cause the O/D to stop working and make the light flash as well as the check engine light because the computer loses the vehicle speed signal it needs.