Truck now won't shut off
Asked by GuruXWNBZ Nov 07, 2018 at 11:28 AM about the 1985 GMC S-15 4WD Extended Cab SB
Question type: Maintenance & Repair
When I turn the key off, the truck keeps running until I put it in gear and stall
it. Replaced ignition switch and restarted engine, turning the key to off did
nothing (engine kept running). Another site said to replace the alternator,
but the problem is parts stores won't take electrical back even if the part
does not solve the problem. I keep hearing about fuel/ignition relays but
cannot find any in the engine compartment. There is one little plastic box
next to the clutch fluid that i don't know what it is for. It is on the driver's
side of the firewall between the clutch fluid on the firewall and the washer
fluid reservoir on the left front quarter. This thing is driving me nuts so any
help would be welcome and appreciated!
2.8L 4WD carburated engine. I recently replaced the starter on it and that
SEEMS ok if it helps
5 Answers
I did replace the IP mylar tracings and some of the gauges on the instrument panel sometime before this problem started.The two events weren't close enough in occurrence to make me suspect that the instrument panel had anything to do with the truck not shutting off. If you could explain your answer in simpler terms I would appreciate it. I am not a mechanic nor am I an electrician so about 1/3 of this makes sense. I do know that a diode allows current to flow in one direction but the rest of it doesn't make sense yet. Are you telling me that current from the alternator could be flowing back thru the system via the IP gauges and not letting the truck shut off? Can I just put the original charging gauge back in and have that fix the problem? There is a small black box on the driver's side of the firewall between the clutch fluid reservoir and the washer fluid reservoir. Around that is the bulkhead connector (to the fuse block?). That little box had to be wire tied shut because the locking mechanism on it broke. Is that the ignition/fuel relay(?) because that component is not marked very well and my eyesight ain't what it used to be. Sorry for posting this twice but the grey box above this answer box says "no answers yet" and you have already replied and so have I.
ok, thank you, but I keep forgetting to tell the forum that these are dial gauges and not (charging) lights.
I liked your answer tennisshoes, but I would not have thought of that ever. Can I replace the new Volts/Alternator charging gauge and see if that makes a difference? Do I replace all the gauges one by one and see if that solves the problem? All I know about the alternator is there is a black and red wire topside on the alternator, along with a charging line that a friend said should put out 14.5 volts. Please explain what a cross-connected wire is?
Thank you for the explanation on the cross-connect. I thought so but wasn't totally sure so I had to ask. The old gauge did not have a light just a needle. I guess this is where i go looking around the engine and under-dash wires to see if there is a cross connect?
If I understand this right, this is a wiring diagram that shows a (blocking) diode inbetween the ign switch and the voltage gauge to stop the current from the gauge and/or alternator. This would keep the current from reactivating the igntion switch when the it's in the lock/off position? Thank you for all the help, I never could have figured this out on my own...
