1998 S-10-E Electric Truck
EV1 System 110 Inverter/Drive train

DTC

Dianostic Trouble Codes

===

1998 S-10-E Electric Truck
EV1 System 110 Inverter/Drive train

DTC-104

DTC-104 is described as auxiliary battery low voltage.

We recently noticed that the S10E's 12v auxiliary systems were not being
supported by the APCM and invertigated.  When the auxiliary battery
is resting at key-off  it should have nominal 12.x v level; vs,
key-on the 12v systems should  increase to +/- the 14.2v level.  The
DTC-104 diagnostic instructions lead us to item 11, and the stock 
answer of "replace APCM".  Well, that would not be any fun, so we 
ventured to dianose what had failed in the APCM.

The pictures below show the results, a burnt transformer leg which, when 
diagnosed, led back to a failed rectifier, a Schottky Rectifier PN  203CMQ100.

After various testing as noted below the rectifier was determined to be 
the root cause of the burnt transformer leg.  The transformer tested nominal 
so the leg was repaired and the transformer placed back in service.  The 
rectifier was then replaced with NOS stock and the APCM put back in 
service.

DTC-104 then successfully cleared and the APCM 
operates nominally.



-- pictures to follow --