3500 4x2 Pickup L6-359 5.9L DSL Turbo (1994)
5. Start and run engine.
6. Apply 8.5 to 9 inches of vacuum to warning switch and observe warning light. If light goes out, switch vacuum hose is either loose or leaking. If
light remains on, leave engine running and continue testing.
7. Apply 20-25 inches vacuum to switch and observe warning light operation. If light now goes out, switch is at fault and should be replaced. If light
remains on, continue testing.
8. Reconnect vacuum hoses and replace original warning switch with. known good switch. Run engine and observe warning light operation. If light is
now off, old switch is faulty. If light remains on, problem is in wiring between switch and warning light.
