04 international dt466 electric back up brake not working

[Ryan Bianco]

I have an 04 international dt466/4300 when key is off or just in on position without truck running the backup electric brake booster not coming on. When truck is running brakes are fine.
I’m concerned if the truck is on the road an stalls out there will be no brakes.
Where do I start?

 

[r3gulator3]

Remove the electric lead from the motor, hook up a DMM (Digital Multi Meter) and press the brake and see if there is voltage. If not follow that wire back there will be a relay. Check powers and grounds there and make sure the relay functions.going back in the system there’s the brake switch on the pedal and a fuse.

Most common failures are the brake switch (and yes the brake lights can still work because the motor and the lamp come from 2 different circuits) and that relay.

 

[Ryan Bianco]

Ok thanks,
I’ll try that and get back to you.