gpr issues

[panheadjay]

my truck has made it 240,000 miles without starting issues, now that its cold it don't wanna start. now i replaced the gpr, it didn't help, so i tested the new one. there is no voltage coming out of the right side of the relay when the key is on, so i go get another gpr and same problem. i checked voltage on the incoming side and there is 12v's, with the key on the small posts have 12 v's, but none on the outgoing side. do i need to check for a bad fuse or anything else? my dads service truck has the same issues but it has 10 v's coming out of the out going side, which probably ain,t enough, right?

[goldgoose]

Here is what i know, like you mentioned, one big connector should have battey voltage at all times, while the other should only have it when glowplugs are active. on the smaller connectors one should only have voltage when the key is on, while the other is the control side (aka it goes to your pcm or ecm how ever you want to call it, and it controls when to turn on and off the coil by allowing a path to ground, to allow voltage to glowplugs).

By what I understand you have an issue with the control side of the relay, (the side that goes to your pcm/ecm) either a wire is broken, or your pcm/ecm has lost the ability to control the system or it just does not want/need glowplug activation.

The glow plug system is electronically controlled by the powertrain control module. If the temperature is below 55°C (131°F) the powertrain control module will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the engine oil temperature (EOT) sensor and the barometric pressure (BARO) sensor, the powertrain control module determines how long the glow plugs will be on.

Perhaps your oil temperature reading is out of wack? try unpplugging yout eot sensor? and see if it comes on? does plugging in your block heater help?

[panheadjay]

i checked it when the engine was warm, i didn't know at the time that it would not power the glow plugs when the engine is warm. i checked it after setting all night and it supplied voltage to the plugs, so my next step was to check the glow plugs, and i had two good ones. i changed them yesterday, but it warmed up here to 50*, it started no problem. i'll just have to wait and see when it gets down to 20* and see if i fixed it. thanks for the reply.

[panheadjay]

i forgot to add, yes plugging it in lets it start fine.