Starting Issue Glow Plug Relay

[joker87]

My M1009 recently decided it doesn't want to start anymore. Just cranks and cranks. Read all the trouble shooting in the TM's and a whole mess of other post.

Here's what the deal is. I replaced the glow plug relay because when you turn the key on it would just keep clicking again and again. When I read the volts on the glow plug relay its 24v on the top and 24v on the bottom when the key is on. Everything I have read states the bottom with the orange wire should be 12v. I've tested the glow plug module by pulling out the card and testing each circuit as stated in the TM. The orange wire that runs to the bottom of the glow plug relay reads 24v when it should read 12v. The vehicle has never been or attempted to be converted from 24 to 12v. It only had 10k on it I purchased it from GL and it is very clean compared to some of the others I’ve seen. I thought maybe one of the fusible connections shorted out but I can’t find any and wouldn't think a short would make something read 24v when it should read 12v.

Any thoughts or ideas would be greatly appreciated.

 

[doghead]

If you read the troubleshooting portion in the -20, it will tell you if you have 24 volts on the "bottom" or output side of the relay, you have bad glow plugs(there is no load to bring the voltage down.

What relay brand and part number did you install? Did you test it for an isolated coil?

 

[nap159]

I had a similar issue. Turned out to be the glow plug controller circuit board needed to be replaced as it had a burnt smell to it. I could not find a replacement one. I ended up using a snowplow relay and bypassed the resistor. By doing that I was able to use the glow plug with the smaller tab. Those were the later "fast" style glow plugs. I then installed a simple switch. With a 12 volt gauge installed on the load side of the solenoid you can easily see if the glow plugs are getting voltage. Some have told me that the "fast" glow plugs need to have voltage "pulsed" to them. I just flip the switch for about 10-15 seconds depending how cold it is, and it fires right up. I have used those glow plugs for about 5 years now with no troubles.

Hope this helps you.

 

[joker87]

I installed a NAPA ST85. And no i did not test it for an isolated coil. How do you do that.

 

[doghead]

Check both small terminals(one at a time) for continuity to it's mount tabs. There should be none.

Then, pull the wire and measure all 8 of your glow plus for resistance. 1-3 ohms.

 

[joker87]

I assume the small mount tabs you are refering to are the two on the relay. if so yes i did check those and they were 12v with the key on and nothing with the key off. i did spot check a couple of the glow plugs and they ranged from .47-1. I read that this could be normal if they were not the orginal glow plugs. i assume this information is incorrect then? I will check all of them in the AM. If it is the glow plugs what brand do you recommed. someone on the FAQ thread suggested "AC60G".