glow plug relay voltage
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glow plug relay voltage
Ok guy's what is the correct voltage on the gpr on the main post? The reason I ask is the passager side show 12.6volt now on the driver side it's show 10.3volts and more turn the key off and on less voltage I get from it. Now I read that this is could be my number one problem to the cold hard start. when I try to start it cold I get ton's of white smoke (unbruned fuel) but once its started it run fine drive's fine.
any help in this would be helpful
thanks
101stcowboy
any help in this would be helpful
thanks
101stcowboy
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
"Driver" and "passenger" don't mean anything; neither circuit of the relay is polarized, and if it's been replaced or is an aftermarket design, it could be wired either way.
Key OFF:
-- Wire from the battery should read aprx. battery voltage, ~ 12.5V
-- Wire to the glow plugs should read zero
Key ON:
-- Wire from the battery will read SOME less, probably aprx. 11V
-- Wire to the glow plugs will read a little lower, but should be no more than 0.3V below the wire from the battery.
So if the DIFFERENCE between the two, WITH THE KEY ON, is more than 0.3V, replace the relay. It's still contacting, but supplying insufficient voltage to the plugs. DON'T bother comparing the battery side with the key OFF to the plug side with the key ON; that really doesn't tell you anything about the relay. If the difference between key OFF and key ON is a lot (like, it goes down to the 9-ish volt range), that would indicate weak batteries (poor-man's load test, basically).
Here's a helpful trick - if it's hard to get from the cab, turning the key on, up to the relay to test the voltage, before it cycles off, try this -- remove the #22 fuse from the interior fuse box. Then turn the key ON, then get up under the hood. You can then use tue fuse as your "virtual ignition switch" - fuse OUT is equivalent to key OFF, fues IN is equivalent to key ON.
Key OFF:
-- Wire from the battery should read aprx. battery voltage, ~ 12.5V
-- Wire to the glow plugs should read zero
Key ON:
-- Wire from the battery will read SOME less, probably aprx. 11V
-- Wire to the glow plugs will read a little lower, but should be no more than 0.3V below the wire from the battery.
So if the DIFFERENCE between the two, WITH THE KEY ON, is more than 0.3V, replace the relay. It's still contacting, but supplying insufficient voltage to the plugs. DON'T bother comparing the battery side with the key OFF to the plug side with the key ON; that really doesn't tell you anything about the relay. If the difference between key OFF and key ON is a lot (like, it goes down to the 9-ish volt range), that would indicate weak batteries (poor-man's load test, basically).
Here's a helpful trick - if it's hard to get from the cab, turning the key on, up to the relay to test the voltage, before it cycles off, try this -- remove the #22 fuse from the interior fuse box. Then turn the key ON, then get up under the hood. You can then use tue fuse as your "virtual ignition switch" - fuse OUT is equivalent to key OFF, fues IN is equivalent to key ON.
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