I have a 95 SDV with a 4.9 in it. In another thread, I described the problem I am having (http://www.cadillacforums.com/forums/ht4100-4-1-4-5-4/91074-egr-solenoid-normal.html).

Anyway, to see if I have a bad injector or not, I did an injector disable test suing PS10. I was able to do a couple of days ago. Now I cannot. When I get into PS10, the indicator shows like "--" mark and I cannot select the injector. I believe I do the same thing at same condition, the transmission at P, the engine running, speed at zero, well, for some reason, I cannot activate PS10 now. Does anybody know why or have any suggestion? It is really weird to me...

Thanks!

Never mind. I figured out...

There are two similar options, PS04(?) and PS10. I must have been confused with PS04 and PS10. I thought the description for the PS10 in the FSM was strange while I was doing PS04 (that I thought I was doing PS10)... PS04 was what I was trying to do (injector disable while the engine running). PS10 is to fire individual injector, not the other way around.