GPR cycle time
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,111
From: Rio Rico, AZ.
Still using the IAH relay as a GPR too.
Senior User
Joined: Nov 2009
Posts: 319
Likes: 1
From: Kirkland, WA
Dan, is the thought behind the manual control to reduce glow plug and GPR usage/wear and tear? I take it the PCM will energize glow plugs at a lower threshold than is really needed for the conditions and manual control allows you to eliminate that usage?
Mountain Pass
Joined: Sep 2007
Posts: 244
Likes: 4
From: Alaska
Any more detail to offer on your modifications? I'm not sure I'm following this. You're using a manual switch to operate the GPR? Or using the IAH relay to engage the GPR?
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
When his GPR went bad he just replaced it with the AIH relay. Now the AIH relay is the GPR.
The AIH isn't really needed like so many emmisions things.
Mountain Pass
Joined: Sep 2007
Posts: 244
Likes: 4
From: Alaska
Thanks PaysonPD,
I wondered if the AIH relay was sufficient to handle the current from the glow plugs. I've disconnected the AIH wires (+ and ground), sawed off the resistor element with a hack saw, but left the AIH relay in place for backup, just in case my Stancor GPR ever goes out on me. Was hoping I could use the AIH relay as a standby - backup GPR. Sounds like Dan has been getting by on the AIH for quite a good long time now, which is great to learn. Good to know my AIH relay would get me out of the woods and back on the highway again if I ever have to connect my GPs to it. Thanks again - and to Dan also for sharing the results of his experiment/experience.
I wondered if the AIH relay was sufficient to handle the current from the glow plugs. I've disconnected the AIH wires (+ and ground), sawed off the resistor element with a hack saw, but left the AIH relay in place for backup, just in case my Stancor GPR ever goes out on me. Was hoping I could use the AIH relay as a standby - backup GPR. Sounds like Dan has been getting by on the AIH for quite a good long time now, which is great to learn. Good to know my AIH relay would get me out of the woods and back on the highway again if I ever have to connect my GPs to it. Thanks again - and to Dan also for sharing the results of his experiment/experience.
Senior User
Joined: Dec 2010
Posts: 400
Likes: 0
From: Knoxville, TN
I'm kinda thinking about going one step further with the LEDs and making my GPR "ON" light red and adding a 12v normally closed relay to trigger a green LED when the GPR deactivates. The GPR will open the relay, turning the green LED off while the red LED is on. May be a little overboard, but kinda cool. What does everybody think?
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Seems like you're trying to indicate red for "wait", and green for "go".
In many, many conditions, there's no need to wait for the GPR to time out before starting your engine, so that seems a lot of trouble to go to.
Just sayin'....
But they're your LEDs, your time, and your truck.
Pop
In many, many conditions, there's no need to wait for the GPR to time out before starting your engine, so that seems a lot of trouble to go to.
Just sayin'....
But they're your LEDs, your time, and your truck.
Pop
Cargo Master
Joined: May 2010
Posts: 3,047
Likes: 9
From: Snohomish, WA
Depending on the brightness of the LED, you may find it annoying at night if the green one is on all the time.
Sounds like your idea would work though!
Sounds like your idea would work though!
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Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
That's sort of what I did. My Scan Gauge has programmable lights on it, so I set it for 12.5V. They come on when Batt V gets below that, so my "GPR Light" serves two purposes -- tells me when my alt is acting up too. BTW, once the GPs shut off, the voltage goes up almost 2V! Those things really load down the electrical system, so a manual setup like Dan is running will also save wear & tear on the alt...
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
If the GPR fails to operate or the contacts fail to close you can just hold a screwdriver across the two large terminals so the GPs heat up. In 5 seconds the tips will glow cherry red and in about 15 seconds the whole length is cherry red.
We all like pics so here's a GP hooked up to a battery charger. There's a reason they are called "Glow" plugs.
We all like pics so here's a GP hooked up to a battery charger. There's a reason they are called "Glow" plugs.
Cargo Master
Joined: May 2010
Posts: 3,047
Likes: 9
From: Snohomish, WA
Note to self: After hooking a glow plug up to the charger like shown above. Let cool down for a VERY long time before relocating to another place. 
Pulled a dumb-dumb once, thought I was picking up one of the other GP's......figured out real quick I wasn't.
Pulled a dumb-dumb once, thought I was picking up one of the other GP's......figured out real quick I wasn't.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
Cargo Master
Joined: Jun 2003
Posts: 3,292
Likes: 6
From: Ardenvoir, Washington
That's sort of what I did. My Scan Gauge has programmable lights on it, so I set it for 12.5V. They come on when Batt V gets below that, so my "GPR Light" serves two purposes -- tells me when my alt is acting up too. BTW, once the GPs shut off, the voltage goes up almost 2V! Those things really load down the electrical system, so a manual setup like Dan is running will also save wear & tear on the alt...
and it will tell you within a .10 of a volt if the GPR is on or off and it also great for checking your alternator voltage.. I leave mine in the cigarette lighter all the time..