M1008 starter running-on

[Randyw]

I have a 1984 CUCV 1008 and the other day while at my deer lease the truck died. Immediately the starter reengaged and continued to turn over while the key was off. It ended up melting a small wire running to the distribution block on the fire wall behind the batteries and tried to melt the battery terminals. Today I traced the wires put new wires on along with a complete brand new starter assembly. When I touch the small red wire to the post on the distribution block the starter engages. Any idea what could be the problem?

 

[Jeepadict]

About a month ago there was an identical thread about this very subject. Do a little searching back and you'll find it. Lots of info for all the variables from solenoid to ignition switch.

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[98G]

Doghead starter relay mod is in order...

 

[Randyw]

How is the Doghead starter relay mod done?

Doghead starter relay mod is in order...

 

[Jeepadict]

Doghead starter relay mod is in order...

Many people will disagree with this statement.

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[98G]

How is the Doghead starter relay mod done?

doghead starter relay modifcation

*** WARNING LABEL *** Disconnect both batteries before attempting this procedure ____________________________ Credit goes to doghead for his instructions in thread "underdash starter relay" and the wiring picture as well. This modification replaces the standard GM underdash starter relay, GM...

www.steelsoldiers.com

 

[98G]

Many people will disagree with this statement.

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What's the downside to it?

 

[Jeepadict]

What's the downside to it?

Some of the purists (aka old guys) that have been working these trucks their entire careers like @cucvrus will tell you that the original design is tried & true with the Army running the snot out of many of these units and never added complication to a simple circut. Some swear by it, some don't. Unfortunately, giving blind suggestions without helping someone with fundamental troubleshooting is essentially "blindly throwing parts at it" which is not effective and costs the guy more money that he may need. The OP already blindly replaced the starter without first verifying it was faulty. Someone immensely familiar with a Squarebody or old vehicles in general or capable of reading the applicable TM will make most effective of their time and bring the truck back online faster with less downtime and cost incurred. One must find/diagnose the underlying problem before a modification should even be considered or replacement parts installed.


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[98G]

Some of the purists (aka old guys) that have been working these trucks their entire careers like @cucvrus will tell you that the original design is tried & true with the Army running the snot out of many of these units and never added complication to a simple circut. Some swear by it, some don't. Unfortunately, giving blind suggestions without helping someone with fundamental troubleshooting is essentially "blindly throwing parts at it" which is not effective and costs the guy more money that he may need. The OP already blindly replaced the starter without first verifying it was faulty. Someone immensely familiar with a Squarebody or old vehicles in general or capable of reading the applicable TM will make most effective of their time and bring the truck back online faster with less downtime and cost incurred. One must find/diagnose the underlying problem before a modification should even be considered or replacement parts installed.


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My understanding is starter run-on is for sure a bad relay. So we have a pretty solid diagnosis. (Correct me if this is a misconception)

If replacing a bad relay, replacing with a higher reliability relay is a good idea.

Pre-emptively replacing the weaker relay with one less prone to fail and take other parts with it is something I would also generally advocate for, in the context of how often the stock one fails.

Like you I generally dislike to diagnose by means of throwing parts in a near random basis. Also, I am firmly of the opinion that not every modification is an improvement.

 

[Jeepadict]

My understanding is starter run-on is for sure a bad relay. So we have a pretty solid diagnosis. (Correct me if this is a misconception)

If replacing a bad relay, replacing with a higher reliability relay is a good idea.

Pre-emptively replacing the weaker relay with one less prone to fail and take other parts with it is something I would also generally advocate for, in the context of how often the stock one fails.

Like you I generally dislike to diagnose by means of throwing parts in a near random basis. Also, I am firmly of the opinion that not every modification is an improvement.

A hung starter can be a few different things with this platform courtesy of the design GM has employed for nearly 40 years. The stuck relay is only one probability that is unique to the 24v CUCV. Example, our fire district has a 1008 that the Forest Service modified back to a 12v system...so that truck defies all the 24v rules which means that specific CUCV will never have a bad relay. Other than the 24v relay that is a known problem child, there's also the possibility of a stuck solenoid, and/or my most prevelant nemesis (I've had about 11 go bad on me thru the years) is a stuck ignition switch or push/pull rod in the column.

Just because it's the most obvious cause for you doesn't mean the OP's truck is doing that. One must do proper systematic troubleshooting to find the root cause. Blindly replacing parts is foolhardy and expensive.

First step in any troubleshooting: duplicate the discrepancy. Step 2: split the problem in half and go from there.

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[MarcusOReallyus]

What's the downside to it?

None, functionally. As mentioned, some purists object.

After reading many, many posts on the topic, my guess is that Chevy got a bad batch of relays, leading to this common problem. However, not ever relay was bad, leading to some people never having any problem.

But on another note, it's a pretty heavy dose of overkill. Antennaclimber measured the current at 9 amps, so a 100 amp relay is a bit much. If mine ever failes, I'll replace it with a standard 30 amp automotive relay.

 

[MarcusOReallyus]

Just because it's the most obvious cause for you doesn't mean the OP's truck is doing that. One must do proper systematic troubleshooting to find the root cause. Blindly replacing parts is foolhardy and expensive.

DING! DING! DING!

We have a winner!

 

[cucvrus]

1.) Check the CCA of the battery's and have them properly load tested.
2.) If needed repair the hard start condition to avoid long drawn out cranking times.
The vehicle should start after the wait light goes out. Extended cranking will cause problems. Weak battery's more problems.
That has been my experience.
3.) Not my truck so if you want go ahead and start cutting wires and placing a Ford solenoid under the dash. I had them stick more times than a CUCV ever did. Anyone ever recall tapping a Ford solenoid when the starter stuck on? Good Luck.

 

[Randyw]

Thanks for all the help guys! As of right now both batteries are new just replaced them a couple weeks ago and they are fully charged. Starter and starter solenoid is brand new just replaced it yesterday. I will try the relay mod and see if that is the problem. When truck was running, never had any issues with long cranking times truck usually fires right up with no issues.

 

[98G]

Thanks for all the help guys! As of right now both batteries are new just replaced them a couple weeks ago and they are fully charged. Starter and starter solenoid is brand new just replaced it yesterday. I will try the relay mod and see if that is the problem. When truck was running, never had any issues with long cranking times truck usually fires right up with no issues.

Please post back with your results. I hope to learn from your experiences.

Thanks!

 

[cucvrus]

Both batteries can be new. My point is are they properly charged? Check out this chart. The battery can have 12 volts and still only be 50% charged. The cranking amps must be tested and the load tester is the only way I know to check that. New Battery's do fail. On a CUCV replace the battery's in pairs. The weak one will feed off the stronger one. And it could also be a bad starter. Over 28 years of CUCV ownership and experience. Good Luck.

 

[Jeepadict]

Please don't hack into a harness to do the relay mod without verifying the remaining possible culprits are behaving. The ignition switch is easy to check. Verify starter is still stuck on by momentarily connecting the batteries. If still misbehaving, disconnect the column harness and try the batteries again...if the starter is quiet the switch is your problem. If the harness is disconnected and starter still runs, remove the 24v relay and than see is it still spins. As mentioned above a standard automotive relay should fit for testing purposes.

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[Randyw]

Thanks everyone for the help. I did the doghead mod and problem fixed. Truck fired right up.

 

[doghead]

1.) Check the CCA of the battery's and have them properly load tested.
2.) If needed repair the hard start condition to avoid long drawn out cranking times.
The vehicle should start after the wait light goes out. Extended cranking will cause problems. Weak battery's more problems.
That has been my experience.
3.) Not my truck so if you want go ahead and start cutting wires and placing a Ford solenoid under the dash. I had them stick more times than a CUCV ever did. Anyone ever recall tapping a Ford solenoid when the starter stuck on? Good Luck.

It’s not a ”Ford” solenoid.

By definition, it’s a relay.(not a solenoid).

There is much more to the reason I chose the relay that I did. If you do some research, you would understand why.

Some people just don’t want to change anything. That’s fine too.

It’s a shame that some only bash or put down others ideas in the forums(rather than try to understand).

I am not of the camp that simply replaces parts or paints things.

I consider the relay mod as a modern day “RECALL”.

In the end, do what you like and be happy with “your” choice.

 

[cucvrus]

An unsafe recall at that. Still requiring more R & D. The sealed ice cube relay or a replacement stock relay is the safest replacement fool proof part for this recall if any is ever needed. With your suggested relay there is a lot of open unsealed positive studs under a completely negative steel dash board. Even taped up it is risky at best. How can it be that they lasted all these years and this update is needed? I understand that it works but so do other safer alternatives that don't require cutting the wiring harness and altering it. That is my point. Not everyone is going to think it all the way thru and make sure of the sealed positive terminals. That is my point. Good Luck. Not my truck is all I will say. I have to get back to replacing parts and painting.