2305 diode smoking

Bubba Tex · Apr 30, 2012

Can anyone identify which system has the 3 amp diode located under the dash that has the brown and green wires running to it?

When I turn the key it sizzles, melts, then the magic smoke escapes. I replaced the two starter relays in hopes that was the problem...it wasn't.

bucktaker · Apr 30, 2012

diodes are not rated in amps..... means you have a short somewhere causing a overcurrent to breakdown the diode. check it with a meter

kebo · Apr 30, 2012

bucktaker said:
diodes are not rated in amps..... means you have a short somewhere causing a overcurrent to breakdown the diode. check it with a meter

FYI, diodes do have current ratings too!

Maximum (average) forward current = IF(AV), the maximum average amount of current the diode is able to conduct in forward bias mode. This is fundamentally a thermal limitation: how much heat can the PN junction handle, given that dissipation power is equal to current (I) multiplied by voltage (V or E) and forward voltage is dependent upon both current and junction temperature. Ideally, this figure would be infinite.

chipsndust · May 1, 2012

Bubba:

Hope these help

bucktaker · May 1, 2012

kebo said:
FYI, diodes do have current ratings too!

Maximum (average) forward current = IF(AV), the maximum average amount of current the diode is able to conduct in forward bias mode. This is fundamentally a thermal limitation: how much heat can the PN junction handle, given that dissipation power is equal to current (I) multiplied by voltage (V or E) and forward voltage is dependent upon both current and junction temperature. Ideally, this figure would be infinite.

My point was they are not RATED by current Like a Fuse . All devices have current ratings they will handle in normal operation

Bubba Tex · May 1, 2012

Thanks Chipsndust, from a cursory look, it seems that this is the circuit from the seat safety switch. Kind of odd since I just replaced it a few months ago. Now comes the fun of tracing the wires to check for problems.

Bubba Tex · May 1, 2012

I believe I found and fixed the problem.

The wires coming from the seat safety switch were routed through a hole barely large enough to let them pass. I seems that they had worn through and were grounding to the plate that the seat sits on. I snipped, re-soldered, taped and re-routed the wiring to a better place. I will need to replace the seat switch, (again), as I had to jump the connection to keep her running while in drive.