My 1989 blazer shuts off intermittently while driving down the road. But only when my heat blower motor is in high position with the switch. Turn the switch to a lower position and truck runs fine. Any thoughts??

 

What is required to get it to start and run again when this happens? Does the dash gauge for voltage drop significantly when you are in high speed blower mode?

George

 

Thanks for your reply. When blower motor is in high the amp gauge stay the same. But when truck shuts off so does the amp gauge. To restart put the truck in neutral and starts right back up.

 

I think whats happening is that a circuit is being stressed by the high amp draw of the blower motor and either your ignition (coil or ICM) or fuel injector(s) are shutting down from low voltage. There may be corrosion or a wiring fault some where. I don't have good wiring diagrams for your year so I cant't do my thing looking for the most logical place to start so I suggest getting a voltmeter on the power wire for the coil and then the ICM and see if the voltage drops out during an event. They are usually pink.

Oh, and welcome to the forum.


George

 

Ok thanks George I will give that a try

 

Another possibility is a bad ground that is lifting under high current from a loose or corroded connection and providing less net voltage to the module, etc. Again I don't have a wiring diagram for your truck but the main grounds are at the back of the engine cylinder heads, the radiator supports, fender wells, etc. Check that they are all clean and tight.


George

 

I went through my wiring diagrams for the one closest to your year and the ground for the ICM is shared with the blower motor at the back of the two cylinder heads so this indeed a possibility.


George

 

Great thanks Again George