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6.9 Melted Wire, Now Don't Start

 
  #16  
Old 05-15-2019, 07:45 PM
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I'm double and triple checking my voltages here. It's confirmed over nothing on the small terminAl with the GPR activated. Without jumping, one large post directly connected to the battery is 12.66 and the large terminAl to GP is showing 12.39. I think that means my relay is no good eh?
 
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Old 05-15-2019, 07:48 PM
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So if my GPR is bad, that would explain why my glow plugs weren't glowing red when I jumped them through the relay eh? Even though I have full power going through the wires the relay isn't releasing the power?
 
  #18  
Old 05-15-2019, 10:08 PM
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the best way to test GP without removing them is using a 12 Volt Test light you connect the Alligator Clip to the Positive Battery Terminal disconnect the wires from the Glow Plugs and then touch the tip of each Plug with the test light, IF the light Does not Light up then the GP is Open or Bad.... very seldom do our Glow Plugs Short to Ground, but it is possible .... the wires on the OEM 6.9 Glow Harness are a resistance wire, and IF you use a Bypass switch to Fire the Relay then you should not hold the switch longer than 3 Seconds.

on my '83 F250 with a 6.9 I never need to use the Glow plugs unless the temps are below 45F on my 93 7.3 I have to fire the plugs for 3 seconds on the first start of the day no matter what the temp is.
 
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Old 05-15-2019, 10:24 PM
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Glow plug Relays should have an Isolated Coil like this image.......
 
  #20  
Old 05-16-2019, 04:58 AM
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Originally Posted by Catlan Zuliani View Post
Everything checked out except for the last part you mentioned, I'm not getting any reading on the small tetminal when I jumped it. Is this suppose to be checked with the button pushed rather than jumping?
This is a brand new relay after the melted wire incident, so I'm thinking either I'm checking it wrong or I need another body to push the button rather than jumping, cause like you said it has to activate by clicking to send power to the small terminAl right?

i think you read it wrong. .


to get power out of the relay, you need to put both positive and negative 12 volts to both small terminals. positive to one, negative to the other. then the relay should click on. this will close the contacts inside and let power flow from one large terminal to the other.
too "jump" the relay, you need to jump 12 volts to the hot side small terminal. this will close contacts and let power go tot the plugs.
another way people jump the relay is to jump across both large terminals, but this usually produces a large spark.

BUT if there is not a ground wire connected to the other small terminal, the relay will not work.
unlike starter relays which are externally or case grounded, glow plug relays are internally grounded and need a ground wire connected to one of the small terminals.
 

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