Does anyone know the resistance value of a '96 starter diode?
Basically mine is gone and the van will not start without one.
Starter relay cluster contains 3 [FOAB-14B192AA as listed on relay] [FOAZ 14N089 A part number to order from Ford]
and 1 gray diode, in the frontmost slot and just plugs into two of the four slots, that looks like a big fuse.
Can someone tell me the part number and where I could get this part, my dealer said it was dicontinued or tell me:
-the resistance value
-where a manual or schematic that would list the value is
-somewhere I could find this info
Or, could some with access test diode for its resistance value
I'm confused. Diodes are semiconductor devices, whose resistances depends on the forward bias voltage. Ideally it's zero in one direction and infinite in the reverse direction. There are no fixed values. Are you sure you are talking about diodes? Where exactly is this thing?
To test a diode use the diode function on your DMM to perform a voltage drop test. However on some larger diodes the voltage that a standard multimeter delivers isn't enough. So you have to test it with a load.
To test the diode with a load apply a low voltage AC current to it with a transformer and use a resistor as a dummy load to measure the output.
Follow the schematic for the half-wave rectifier where it says R is where you put the resistor. Now using your DMM measure the voltage from the resistor. Place your positive probe on one end and your negative on the other.
If you read a DC voltage the diode is fine. If you read an AC voltage the diode is shorted if you don't read anything the diode is open.
Last edited by krankshaft; 10-31-2007 at 01:33 AM.
the later Aeros with high speed processor for OBDII EEC-V engine control added an additional protection diode in the relay box to reduce further the EMF kickback voltage from the PCM relay to further protect the delicate PCM electronics. wiki relay protection diodes.
I've never seen one fail in Fords. forward and reverse bias test for proper diode action. test with high impedance R testing for leakage
if your's is missing, get a 3a or 6a 25v or 50v rectifier diode at Radio Shack and put in with band cathode end on +12v side contact in relay box socket.
this diode has nothing to do with the starter relay or start circuit.
always replace the PCM relay with one that has internal diode protection also. like wearing 2 condoms
additional protection internally in the PCM with V. surge protection devices
If that's the case, the only way this diode could have affected the starter relay is if it failed in shorted mode. However, that's highly unlikely since diodes usually fail in open mode. Could it be that you put this diode in backward so the current is going through it instead of through the coil?
A simple test will be to remove the diode and see if the starter cranks. If not, the starter itself or the solenoid are more likely culprits.
RE: 96 Aerostar Diode
I was told by the dealer the item was a diode and all I needed was the value and I could find a replacement, if I remember corectly it said diode on top and had a schematic symbol of a triangle intersecting a vertical line, the plug was lt. gray about 7/8'' high x 1-1/8' wd x 3/8" thk
Located in starter relay cluster (black about 8" lg x 2" wd with 4 plugs protruding from bottom) just under drivers side hood hinge.
in the frontmost, first of four slots, two of the four slots, looks like a big fuse.
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