Inside the transmission! Got to remove the trans oil pan to get to it.
They were available either with manual or automatic transmissions.
A4LD - 4 speed automatic
Turbo Hydra-Matic 700.
According to this website;http://market.autopartsfair.com/ford-transmissions/find_product.HTML?model=ranger_2wd&year=1989You have an A4LD transmission whether it is a 2wd or a 4wd.Answerand what is funny is that tranny is so bad ford says it isn't a ford tranny..mercury designed it and ford made the "mistake" of using it for their trucks AnswerThere were three transmissions available in 1989. There was the Mitsubishi unit that was often coupled with the 2.9 liter engine and the Mazda M5OD (which is in my 1992 Ranger) for the manual transmissions. Then, there was the A4LD automatic.
On your 1989 Ford Ranger : The vacuum modulator valve is on the passenger side of the A4LD automatic transmission ( it might be behind a heat shield )
http://www.longenterprises.com/ they have exploded views of lots of transmissions
on the drivers side frame rail
Yes, it is.
1 Oil Filter 1 Fuel Filter 1 Automatic Transmission Filter 1 Engine Air Filter
located below the oil filter
It could Be a couple of things but first try changing your fuel and air filter. is it an automatic?
It will be about 4.7 liters in a v8. This will be with changing the oil filter and if there is no oil already in the vehicle.