I can't recall ever coming across this info when surfing through the archives. So tonight I decided to see if a grid heater control box from a 91-93 IC motor would work on a 89/90 Non-IC motor and wiring. Well I can say if works just fine...well at least to the point of the "wait to start" light coming on in the info center, and the grid heaters doing their charge up and 10 sec cycle.

Just a FYI...

 

FYI, the grids on 91.5-93's are controlled by the pcm.

 

Well the grids might be controlled my the PCM on 91-93's, but the grid heater control box works just fine on the 89/90 wiring.

Main difference between the two is that the 89/90 control box does not do the "wait to start" and grid heater cycle every time. The grid heaters on a 89/90 only come on in short burst....the "wait to start" light only comes on at -15*C or colder.