1984 GMC Van

Engine Mechanical problem
1984 GMC Van V8 Two Wheel Drive Automatic

1984 GMC Van with 6.2 diesel engine.
Starter continues to run after key is released.

TEST: I tested wire that goes from ignition switch " start" position to selenoid " S" terminal, (test performed with wire disconnected from selenoid " S" terminal).
TOOL USED: Digital multimeter
RESULTS: Key on start position=12 volts
key released to run position=0 volts

TEST: Bench test starter and selenoid (off vehicle) as follows: 12 volts to battery lug on selenoid, jump with screwdriver between battery lug on selenoid and " S" terminal of selenoid, thereby providing 12 volts to " S" terminal of selenoid.
RESULTS: Screwdriver touching " S" terminal= starter engages and runs.
Screwdriver removed (power terminated to " S" terminal)= starter stops.

These tests indicate to me that wire to " S" terminal of selenoid is OK, that selenoid is OK.
Somehow, power is going to selenoid after key is released, causing it to stay engaged.
I have been told the starter itself has a short, but no one can explain how or how to test it.

I am 62 year old cancer patient living on $674 per month disability and can not afford to replace starter without being absolutely sure it is at fault.

Same reason prevents me from making a contribution, I am sorry.
December 27, 2009.

Check the park and neutral position switch if it has power on the purple wire during cranking position power present the P/N switch is defective If power not at the purple at the P/N switch the ignition switch is defective.

Dec 27, 2009.