The ECM will be in 1 of 3 places: It will be behind the kick panel in the driver's foot well, in the firewall under the brake booster or on the firewall in the pasenger side footwell just above the trans hump.
On the "Foreign car" Fords, the ECM is behind the kick panel in the passenger side footwell. I don't think the Mazda B-truck and the Ranger were close enough in 1989 for the Ranger to be a "Foreign car" Ford and the ECM location was identical for the Explorer, Aerostar and Ranger starting in 1990, so I'm betting you'll find the ECM on the firewall in the passenger side footwell. You'll know you have the ECM when you find the 104-pin connector held on with a 10mm bolt.
Hope that helps!
Monday, August 2nd, 2010 AT 9:26 PM