1990 zr1 help continued...

[Chris26]

Does the ICM control spark and the injectors or both???

[XfireZ51]

Does the ICM control spark and the injectors or both???

The ECM controls spark timing, the ICM CONTROLS START-up, limp home mode,
And firing of ignition coils. Injectors are controlled by ECM.

[Chris26]

Thank you!!!...I might have a fried ICM (under the plenum)...seems that mice got into the valley at one point and caused a small fire!!! The engine did start before but not anymore.

[Paul Workman]

Thank you!!!...I might have a fried ICM (under the plenum)...seems that mice got into the valley at one point and caused a small fire!!! The engine did start before but not anymore.

Oh, that ain't good, for sure! But, don't jump to conclusions until you have the harness repaired...speaking from experience w/ burnt harnesses. There are fuses and fusible links scattered about that may have done their job.

I'd concentrate on the harness - getting that back in shape, scanning it for codes, and go from there. I'd say (hope) your chances are better than 50-50 that the modules will be OK (they ARE very robust!)

[Chris26]

Thanks for the reply!!! The harness is not that bad just a little seared..
Someone at one time installed an extra hot lead that connected directly from the battery to the alternator...they ran it under the plenum...Seems that a mouse chewed on it and created a ground through the block...with all the dirt and debris
igniting a small fireball. The secondary port actuators have the vacuum lines melted...