KDS Yellow box blown diode repair

[NDT]

Has anyone been down this path already? Big power diode blown up near mosfets that juice the glow plugs. Not sure of rating, will order 50 volt 30 amp or so and see if it fixes box. Box would not glow.

 

[FloridaAKM]

Question is, are there anymore components fried in the board when the diode let the magic smoke out & incinerated itself?

 

[NDT]

I believe you are right. The diode is connected between the source and drain on the three 75344G Fairchild MOSFETs, not sure of the purpose. If someone tried to jump the truck off reverse polarity, the +24 volts would travel through the chassis to the engine, backfeed the glow plugs, and then 24 volts would try to flow through this small diode to all the vehicle loads, causing it to blow up. Since the mosfets don't work, more is smoked than just the diode.

 

[papakb]

1.5KE47CA bidirectional suppression diode

 

[NDT]

Thanks papakb, that means that since the suppression diode is "optional" and not part of the circuit required for the mosfets to switch, either the mosfets are blown too or the upstream gate trigger voltage is not longer present which I have no way to fix. Hmmm.