M1009 doesn't start right

[Stratoghost]

Before I tell you what it was doing and how I "fixed" it, let me tell you a few modifications I did to it prior to the incident.

I did the doghead relay mod, replaced the glow plug relay with one that was recommended, did the resistor panel reroute mod and added a glow plug button in the cab. I also installed a 12v starter but only because my chinese knockoff 24v starter died when I was on vacation in rural Pennsylvania on a Sunday. I was glad I had an internet capable smartphone and this site as a reference.

Anyhow, last Monday I got in my truck to go to work. I started the truck like normal and it ran for about 5 seconds. Then it wouldn't start again. Wait light comes on, it would turn over, but wouldn't start. Given that much info, what do you think it was?

I spent the next week talking to people and searching this site to try to figure out what was wrong. The truck seemed to not be getting any fuel. It was running fine one minute and simply quit. I changed the fuel filter, bled it and checked to make sure the lower fuel pump was working correctly. I then listened for the click of the shutoff solenoid on the injection pump. It clicked. I took off the return line valve and cleaned it out. It wasn't dirty. I checked the air filter, it was a little dirty, but it wouldn't start with it off.

About this time my battery was getting low on charge, so I traded it with the "spare". I took out a glow plug and it tested to 1.3 ohms. I also cranked the engine for 5 seconds and saw a mist coming out of the glow plug hole. I tested another one. It was the same. I checked fuses, connections, grounds. Everything I looked at and tested seemed to be in working order. I followed the TMs as best as I could.

I had a helper push the glow plug button in the cab with the ignition on so that I could test the voltage to the glow plugs. Wait light and other lights come on, but other than that, nothing. I also didn't hear a glow plug relay click. I retested everything and it still seemed fine. I asked the helper if she had pushed the button in all the way and she said she did. With the ignition off, I told her I was listening for a click, then I pressed the button. Click! It clicked, but only with the ignition off.

I put all my tools away and got in the truck. I cycled the glow plugs with the ignition off, turned the ignition on and it started right up.

I will be reading electrical schematics this week trying to figure out what is shorted out, but I am not that great at it. I would appreciate any help as I have not found this problem addressed here on this site. My guess is the glow plug card, but it looks fine and doesn't smell burnt. I probably missed something somewhere.

Love this site btw. The TMs are invaluable as is the combined knowledge and experience of all who work on these vehicles and contribute to this site.

 

[Warthog]

How did you wire the manual switch? Any pics? What GP relay did you use? Part number?

This is how a stock system works.

All the GP controller does is sense the state of all the sensors, engine temp, etc. And then it supplies a ground circuit to the GP relay when needed.

With the key in the run position, 12v is supplied to the relay coil at all times. Only when needed the controller card supplies the ground and the relay energizes.

The easiest way to wire a manual switch is to add a ground wire to the relay. Add a wire to the light blue wire (ground) and then to a switch, and finally to a chassis ground.

When you push the button, the ground circuit is closed, the relay coil energizes and the main relay circuit is closed allowing the GPs to get power.

Also if your truck is still 24v, the 12v starter will work for a little while but will burnout.