M1009 Starting Issue

[Lional]

Ok, so not to long ago I went to start my '85 M1009 and the little blue ground cable from the negative battery terminal to the core support melted. I replaced it and quickly checked my grounds before trying to start he truck again. This time the replaced wire got very hot and the starter was turning extremely slowly and the truck would not start. At this point I double checked some forum posts and dove deeper into the grounds taking off and cleaning/inspecting all of the one I could find in or near the starter systems path. I will admit I am a bit of a noob, but I did check the grounds with a multi meter after re-installation to see if I could notice anything that wasn't right. Tried to start the truck again... extra slow crank and the little wire got hot again, no start. This is when I decided to take the starter out and have it tested and clean the contacts. The starter was tested as good at the auto parts store and back in it went. I tried to start it again with the same results. This truck was converted to 12V about 5 years ago.

Any information on other items to look into or grounds that are easily missed would be a huge help!

 

[cucvrus]

Do you still have the large ground cable located on the right rear cylinder head. That light wire seems like it is pulling all the amps and providing the ground. Not good. I tend to add a few grounds. Frame to engine and engine to body. I use heavy cable and attach it to holes that exist and use star washers. Not saying that is the issue. Also have you load tested the battery's lately. Low amps makes things hot. Be Safe.

 

[MarcusOReallyus]

I'm not agin' adding grounds, but first make sure the stock grounds are good. A look at them will not tell you much. You need to take apart every connection, clean it to shiny metal, and reassemble it, preferably with some dielectric grease to prevent corrosion.

Also, get rough with your cables. Corrosion can wick its way in under the insulation and show no sign of anything on the outside. Push them, shove them, yank them. If it's not in great shape, you want to know. The best way to know is to break them. Then you know.

Then you replace them.

Remember that a 12v conversion needs heavier gauge cables than a stock 24v version.

 

[Lional]

Do you still have the large ground cable located on the right rear cylinder head. That light wire seems like it is pulling all the amps and providing the ground. Not good. I tend to add a few grounds. Frame to engine and engine to body. I use heavy cable and attach it to holes that exist and use star washers. Not saying that is the issue. Also have you load tested the battery's lately. Low amps makes things hot. Be Safe.

Thank you, I dug into it more this weekend and I do still have the ground on the back of the cylinder head. The battery's are just a year old and when cranking the went from 12.13 volts to 10.33 volts I also did verify that there is an additional ground cable from the bar on the firewall to a bolt in the bell housing next to the starter.

 

[Lional]

I'm not agin' adding grounds, but first make sure the stock grounds are good. A look at them will not tell you much. You need to take apart every connection, clean it to shiny metal, and reassemble it, preferably with some dielectric grease to prevent corrosion.

Also, get rough with your cables. Corrosion can wick its way in under the insulation and show no sign of anything on the outside. Push them, shove them, yank them. If it's not in great shape, you want to know. The best way to know is to break them. Then you know.

Then you replace them.

Remember that a 12v conversion needs heavier gauge cables than a stock 24v version.

I did take all of the grounds apart an clean them as well as check them with a multi meter after re installation. I was able to read 12.23 volts across the battery terminals as well as the grounds I could reach with the positive lead on the batter and the negative lead going to the different bolts and wires. I was also able to maintain the 12.23 volts when I directly touched the starter housing with the negative meter lead.

 

[Tow4]

A fully charged 12 volt battery should read about 12.7 volts. Charge the batteries and then load test them.

 

[Lional]

So I finally got this figured out. It turned out to be a faulty end on the main ground cable going to the negative battery post causing the issue. Once that was replaced everything appeared to be working correctly

 

[MarcusOReallyus]

Multimeters are great, but a test light should be part of your toolbox.