Here is a quick DIY for the Glow Plug Relay (GPR) LED Mod. This mod does not necessarily tell you when the truck is ready to start. All this does is let you know when your GPR is operating. GPR operation is based off of oil temp and will continue to cycle until adequate starting temp is met. The GPR can cycle for up to 2 mins. Even though our trucks have enough juice to start, this also helps you minimize the amount of battery power used by letting you know when the GPR stops pulling current from the batteries which at that point allows full current to go to the starter… at least in my theory it does. haha
- One 12v LED Indicator Light form Radio Shack (Part # 276-270) $2.99
- 18 gauge wire (I used green for ‘hot’ wire and black for ground, used green because my GPR already had a small red wire connected to one of the small posts).
- 2 Eyelet Connectors / Ring Terminals
- 2 Splice Connectors
- 1 amp inline fuse
This works with all GPRs. I changed my OE GPR to a Stancor (White-Rodgers) 586-902 Relay. The contact rating on the new relay is 200 Amp continuous and 600 Amp inrush with a 21 ohm coil resistance for up to 2mins. You can order this relay form Mouser Electronics ($52) or at McMaster-Carr ($52) where I got mine. I order from McMaster in the past and knew they get things to you in about 2 days for standard delivery. These were the 2 cheapest places I could find selling them. From all that I have read this is the best relay and really helps with cold starts and issues associated with it. It is a good first step before you start digging into the injectors due to a little white smoke and a hard start from time to time.
Guzzle’s 2002 Ford Powerstroke Diesel Web Page has a great write up for this Relay swap along with a few other mods. Make note our 7.3s are slightly laid out different form the 99-early 03 7.3s so don’t be alarmed if the pics don’t match exactly what is under your hood.
Welcome to guzzle's Stancor GPR replacement Mod Web Page
Now for the GPR LED Mod. Here is a good little diagram I found that lays things out pretty good visually for you.
- First disconnect both your batteries… rather be safe than sorry when you’re working around hot wires.
- Connect eyelet to your 18 gauge wire
- Connect eyelet to your Outpost to Glow Plug Terminal. This is the large terminal with the yellow/brow wire.
- Run the wire into your cab anyway you want.
** At this point I tested my LED to make sure it worked before I went any further. Twist your red LED wire to you GPR wire, then take your black LED wire and press it to one of your bolts that mount your seats (acts as a ground), turn key and confirm LED lights when ‘wait to start’ light comes on.
- Find a location where you want to mount your LED. I have seen a lot of guys mount it in their gauge cluster on the A-Pillar. I mounted mine right next to the ‘Wait to Start’ light since I don’t have a cluster on my A-Pillar.
- Drill hole and mount light in desired location.
- Connect the wire from your GPR that you ran into your cab to the ‘Red’ wire on your LED with a splice connector.
- Connect ‘Black’ wire to your ground wire with a splice connector.
- Run your ground wire to a place in your truck where you can connect to a bolt in the body to ground the current. You can use another eyelet if desired.
And that is all it takes.
Here is a pics of my GPR mounted in the same location as the OE relay.
A pic of the LED light mounted to dash and off
And a pic of the LED lit while the GPR is operating with the ‘wait to start’ light is off.