Runaway Starter M1009!

[tgtaylor64]

Well it happened and I need to understand how. I did the DHM over ten years ago and never had a problem. Fortunately, I was able to disconnect the front negative cable in under 30 seconds. It was a cold start and nothing heated up, smoked, or melted down. Truck was bought from the military back in 2008 and is all stock, minus a few upgrades, but still 24 V.

 

[Jeepadict]

In my experience with these GM platforms (Squarebodys and RVs are remarkable siblings) has been one of 2 problems every time...first culprit is the starter solenoid can get stuck in the closed position...second is there's a plethora of parts in the column that can fail prematurely and cause the ignition switch to get stuck. There's always a chance of a harness chafing, but that's never been the case for me.

My first step in troubleshooting would be to unplug the ignition harness near the bottom of the column. All of mine have been a flat single row of terminals. Once the harness is unplugged try reconnecting your neg batt terminal...if the starter is quiet, then 99% odds says the problem is in your column. If the starter still runs, disconnect the solenoid signal wire (small wire at the back of the starter) then try the negative terminal again. If it's quiet then you have a wiring problem with the signal wire (this has never been the issue for me), if the starter still runs then the solenoid is stuck...replace the starter.

Sent from my SM-G970U using Tapatalk

 

[Tow4]

Check the starter first by pulling the wire at the solenoid as J says above. That's the easiest thing to check and is probably the problem. You can just replace the solenoid if the stater bushings and brushes are in good shape.

 

[ida34]

Your problem is the 12-24 volt starter relay under the dash. It takes the 12 volt input from the ignition switch and makes it 24 volt for the starter start terminal. It is a common upgrade to put in a better relay as it is a super common problem for them to stick and eventually burn the truck down if you don't get it disconnected. I am betting your relay is stuck closed. It is part of a cucv only three pack of relays under the dash.

 

[ida34]

Doghead starter relay is must if you get new starter | SteelSoldiers

 

[ida34]

The above link seems to say don't do the upgrade but it shows you the relay you need to check. You can either replace with new OEM relay or upgrade with a starter type relay from a Ford.

 

[ssdvc]

I believe he hints in his post that he has done the DH conversion, (DHM in his text, Dog Head Mod ?).

 

[cucvrus]

I never done any of these modifications. I found that keeping the stock relay in place and maintaining good strong high cranking amp batteries is the key to NO relay issues. It also helps if the CUCV starts after the wait light goes out and you are not cranking in in long cranking cycles to get it started. This all contributes to the relay welding fast and failing. Explain to me. How di the military use them for 35 + years and not have to hack the wiring to do a relay modification. They maintained them and if not the replaced the failed parts and batteries on an as needed basis. Using slave cables and another CUCV helps also as that keeps the amperage up and less drag on the relay. Good Luck. I have returned a few relays back to stock after I seen a quarter melted thru the dash on one. Too many positives under a negative steel dash pad. The plug and play cube relay works well and requires NO exposed connections and NO cutting. Do as you wish. Just making a recommendation and an experienced one at that.

 

[Keith_J]

Check the starter. When you issue the start command, several things happen. A 12 volt signal is given to a relay, locally known as the Doghead relay or its modification. This converts the 12 volt signal into a 24 volt one. This signal energizes a solenoid on the actual starter to throw the pinion gear into mesh with the ring gear on the flex plate. Once meshed, the solenoid completes the circuit, making 24 volts flow into the starter.

If the pinion gear retainer were to fail, the solenoid will remain in the closed state, causing starter run on. There are other failure modes resulting in this outcome. Check the starter along with solenoid and switch.

 

[ida34]

Check the starter. When you issue the start command, several things happen. A 12 volt signal is given to a relay, locally known as the Doghead relay or its modification. This converts the 12 volt signal into a 24 volt one. This signal energizes a solenoid on the actual starter to throw the pinion gear into mesh with the ring gear on the flex plate. Once meshed, the solenoid completes the circuit, making 24 volts flow into the starter.

If the pinion gear retainer were to fail, the solenoid will remain in the closed state, causing starter run on. There are other failure modes resulting in this outcome. Check the starter along with solenoid and switch.

All the cucv had the relay. The doghead conversion is just upgrading the relay.

 

[Curtisje]

I never done any of these modifications. I found that keeping the stock relay in place and maintaining good strong high cranking amp batteries is the key to NO relay issues. It also helps if the CUCV starts after the wait light goes out and you are not cranking in in long cranking cycles to get it started. This all contributes to the relay welding fast and failing. Explain to me. How di the military use them for 35 + years and not have to hack the wiring to do a relay modification. They maintained them and if not the replaced the failed parts and batteries on an as needed basis. Using slave cables and another CUCV helps also as that keeps the amperage up and less drag on the relay. Good Luck. I have returned a few relays back to stock after I seen a quarter melted thru the dash on one. Too many positives under a negative steel dash pad. The plug and play cube relay works well and requires NO exposed connections and NO cutting. Do as you wish. Just making a recommendation and an experienced one at that.

I replace mine with OEM relays. Cost me $26 bucks last time. Haven't had any problems in years.