92 Geo Tracker Multiple Codes

Ive been working on a 1992 Geo Tracker 1.6 with a Suzuki motor Throttle Body inj. Iam getting multiple codes such as Coolant Temp,Throttle Position -intake Air, Manifold pressure. It has a Diagnostic Connection under the hood by the Battery which you have to Jump 2 terminals to retrieve the codes like the older GM,s. I cant get my Scan Tool to work with this Vechile, which makes it harder to tell what is going on. The sensors have been testing good and almost makes me think it could be the ECM. I have got a couple of the codes to go away and even replaced the coolant sensor and after clearing the codes it with the others come right back with in 15 seconds which is usally way to quick for the coolant sensor. The Check engine light was burned out so dont know how long this was going on. Ihave a few diagnostic charts for this but none to check the ECM I have other charts for the old GMS that have it but Iam not sure they will work being part GM and Suzuki. If any one has any isight into this Please Post back .
Thanks