I'm getting a 12 code on my 86 iroc. And the cooling fan wont come on. I checked the relay and its good. When I check for codes by grounding the test pins the cooling fan will come on as long as its in test mode.code 12 says no reference pulses to ecm what does that mean?

Thanks

 

this code 12 will flash three times ( once then one two) look for that 3 times,, then your problem code will flash,, if its only flashing 12 you have no codes,, it works something like that,, look it up its been a while for me

 

code 12 tells you no distributor reference pulses sent to the pcm because the engine is not running
code 12 is expected, everytime you pull codes
code 12 is ignored
it is used more as a check if the computer is responding

 

If your cooling fan will not come on, then that means you either have a bad temp sensor or the sending unit is not working correctly. Check into those first.