Help solving electrical problem

[82 dieselburb]

I have a 94 3500 with a 6.5 Last week when I turned off the ignition the engine would not turn off.I figured out that I had the parking lights on and when I turned them off the engine also turned off.Also I discovered that when the engine is running the parking lights are on even with switch off.So if my parking light switch is on the only way the engine will shut off is to turn the parking light off.I just need some advice to know where to start checking wire etc to see where the problem is.I hate chasing electrical problems.Thanks for any advice

[DickWells]

Where are you GMCTD? One of you old-timers must be able to help this guy out.
If it was me, I'd start searching through the old DP data to see what I could find on ign switch/light switch problems that my old feable mind seems to recall as showing up here back a few years.
I'd take an OHM meter and start at the fuel shut-off solenoid at the IP, and see if I could follow that voltage back to the source, while the ignition was off and the engine still idling. But, I'm not an electronics guy, so my old farm kid tactics are bound to be hit or miss and slow as death.
Do you have good manuals, with complete wireing diagrams? Worth whatever you have to pay imho.
Good luck.
Dick Wells:)

[82 dieselburb]

No I don,t have any wiring diagrams.I'm getting ready to go outside with my volt meter and start chasing wires(not fun).It's kinda wierd.With the ignition on and engine running the parking lights are on with the switch off the engine will turn off with ignition switch.If parking light switch is on it will keep the engine running.So that means than with the switch off and ignition on somehow the parking lights are getting power.With the parking light switch on and ignition switch off the engine is still getting voltage???????Let the fun begin.

[JohnC]

Are the lights on full bright? Long shot, but check the parking light grounds. Sounds like the parking lights are grounding through the ignition system.

(For that matter, check all the grounds...)

[MR.E]

Chasing ground phantoms on my truck as well.
2 ground points affect the lighting circuit.
Check ground G202 at the DLC. Mine is a large brass ring on the upper right of the DLC (as seen lying on your back on the floor) held to the dash metal with a 7mm screw. The other ground is between the drivers side battery and the headlight on the sheet metal. Should be a 10mm screw and star ring. Good luck.

[DaveBr]

You might try putting a new headlight switch in your rig. When they go they can do all sorts of strange things. Besides they're cheap and easier than chasing bad grounds.