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Discussion Starter · #1 ·
I have looked through several threads before posting to determine I might need a glow plug relay. Well I bought one and still no starting, bought another today and still nothing. The glow plugs will heat up if I jump the posts on the relay with a screwdriver. I actually got this 2000 F350 with 142k miles three days ago on trade for a 1999.5 Silverado 1500 so I don't know much of the history on it. I have tested the relay and when the key is powered on I get 12.94 to the power post and two small post. Still, with both NEW relays, I get nothing to the glow plug out post. I live in Raleigh, NC so the weather is on the cold side and the truck will not start without these.

I would appreciate any advice you can give me because this is my first diesel truck.
 

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Check the 4 plugs on valve covers, 2 two on each side to see if one or more are burn`t. this is common thing, not so much on superdutys. if not burn`t use a test light on the 2 outside pins on each plug and check the glowplugs. hook testlight to pos side of battery and test plug, light on plug is functional. hope this helps. lol
 

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Discussion Starter · #3 ·
Check the 4 plugs on valve covers, 2 two on each side to see if one or more are burn`t. this is common thing, not so much on superdutys. if not burn`t use a test light on the 2 outside pins on each plug and check the glowplugs. hook testlight to pos side of battery and test plug, light on plug is functional. hope this helps. lol
Thanks for the reply. Two of the plugs didn't show up on my multi-meter. But when I jump the relay with a screwdriver they will still heat up. Would having two bad plugs cause the relay to not send a signal?
 

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Discussion Starter · #4 ·
Well I checked farther down the line at the 42 point connector this morning on pin # 13 and had no power there. Hopefully this would be a short between the wire going to the pcm and not a problem with the pcm itself. Has anyone read or experienced similar problems?
 

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I don,t think so. Should send signal to the plug even if it is bad. Meaning glowplug

Sent from AutoGuide.com Free App
 

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No,no,no,,, That's not how it works....

You test the PCMs control by removing both sm wires from the relay and determine which one has 12v in it with the key ON. The wire that Does NOT is connected to the PCM and is what it uses to activate the GPs by supplying GROUND. Use a meter and connect one side of it to the battery (+) and the other to the PCMs wire. When cold, and it should be using the GPs, you should see 12v flowing through the meter (make sure it's in DC, test it first across the batteries terminals). Depending on how cold it is you should see that power there for from 30-120secs

Instead of "jumping" the relay, next time just ground the sm terminal on the GPR that the PCM wire was connected to (with the other, 12v, sm wire connected). You should feel/hear that relay throw and activate the plugs...
 

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Discussion Starter · #7 ·
Today I installed 8 new ZD11's, a manual relay switch, and two new batteries. Still not starting. I have checked all the fuses with my multi-meter. I am really not sure what else to do as I don't really understand how the diesel ignition system works. While cranking the engine spins to about 2-300 rpms. Any help would be much appreciated.
 

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First you want to Know the relay activated by measuring the voltage on the large output terminal. Find 12v in the one connected to the battery and see, when cold, the other side has the same...

If not, try grounding the sm term that goes to the PCM (as I described above) to get it to "trip". Then see if it starts.

If so, here's my usual No Start List;


WTS Light? - do you get it when you first roll-on the key? (shows the computer is running)

Do you see cranking rpm on the Tach? Do you have a spare CPS to try?

Is there fuel in the fuel bowl now? Does it refill after cranking? (open the drain level to check)

Can you hear/feel the pump running (below the dr seat, against the framerail)

Could the fuel gauge be giving a bad reading? (Below 1/4 tank?)

Is your truck "chipped"? If so, remove it as a Test.
 

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Discussion Starter · #9 ·
Thanks for all your help! I tried everything and all was fine. I remembered the previous owner mentioning they installed a new transmission so I checked the neutral safety switch. It was close enough to alignment to allow for cranking, but it wasn't allowing the truck to start. After aligning it properly the truck fired right up. I'm still glad to have changed the glow plugs anyways.
 

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Oh,,, I'm afraid that's just not possible..... :(

You may find this creeps-up on you again. The Range Sensor (NSSW) is just a switch that prevents the starter from engaging if you're Not in P/N. It has no other Powers. If the Starter turns the engine over, it's roll in starting is Done. It simply can't do what you describe.
 
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