http://www.troublecodes.net/Volvo/

Went here and cannot find the box, do all 1989 740 Turbos have one? I am at a loss.

 

I think you will find that there are some mistakes in that article.

The 1989 model 740 Turbo did not have the small self diagnostic box as described. The testing and finding of codes on that model year turbo carneeded a calibration test instrument and adapter to test the fuel system and a test diode tester for the ignition system.

The non-turbo had the diagnostic box mounted on the strut tower.

From 1990 the turbo model also had the diagnostic box on the strut tower.

A further mistake, which does not affect your car, is the reference to the '94 and later OBD11 cars. OBD11 was not generally fitted until 1996.

 

Ha, and here I thought hubby and I were both blind.

I think maybe we should just trade this car in.........it is really costing us a lot.