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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3362
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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1991 GMC Topkick 366ci gasoline. Engine Over Speed light

Customer Question

1991 GMC Topkick 366ci gasoline. Engine Over Speed light illuminated while driving and truck stalled. Unable to restart
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 1 year ago.

My name is ***** ***** I will assist you.

Have you checked the crank/cam position sensors?

What about on the bottom of the distributor where the sensor is. Do the wires look frayed or worn?

You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see,
touch, smell, hear, or taste the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

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Customer: replied 1 year ago.
Greetings, I am a mechanic and specialize in vintage and classics. This is a customers truck that I had to straighten out to get started after the plugs, wires, rotor button was changed, when it didn't start before, by a friend of theirs. The lift gate was stuck down as they reconnected the battery wire incorrectly when they had to be charged. I found a blown ignition fuse and loose connections. Got the truck running and my actron scanner gave no active codes and a historical code of 'engine overspeed'. I tried researching that at that time to no avail. Got the truck running and driving and it has been used several times. Got call earlier tonight that while driving and going slow in city neighborhood the truck engine overspeed light illumunated and the truck stalled.
Customer: replied 1 year ago.
I have no experience with "engine overspeed" and would like this explained.
Expert:  Jeremy replied 1 year ago.

Engine overspeed isthe engine is spinning too fast per the cam sensor. Basically it thinks the engine is above 5000 rpms. It was put in to keep the deiver from going too fast in lower gears while going down mountainous roads.