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Now that the weather is starting to get cold we get a lot of " hard start/no start " threads being started. I always refer members to the write up I posted on how to properly check the GP system and in it I mention using a Stancor relay. Thought I would take a minute to do a quick write up on it. The glow plug relay is nothing more than a starter relay, it supplies power to the GP's and turns them off when the PCM tells it to. The problem is a starter type relay simply can't handle the 200amp current draw for up to 2 minutes that the gp's call for when really cold. Every factory relay I have cut open has been toasted inside. Ford charges $60-$75 for a GPR, in my write up on the GP system I also mention the fact that you can use a relay from Napa called the GP109, it won't show on their computer as being the right relay but I have verified with the manufacturer that is exactly the same relay as the stock unit except the mounting tabs are rotated 90 degrees. The wiring has enough slack for it to work and it can be had for around $20. But in the end it is no better to handle the 200amp draw than the factory unit. The best choice is to use a Stancor 586-902 relay. These can be had online for the mid $30 range. I bought 6 of them from a fire truck manufacturer that was going out of business for $20 each, I also believe Graingers sells them. One look at it and you will see the difference!! It is probably more than twice as large and weighs a lot more as well. This relay is made to handle the 200amp continous draw our gp's demand. I have had it oin my truck for 3 or 4 years now and it has never started so good. The mounting tabs fit our mounting studs perfectly, I did have to grind off a small wing off one of the tabs to sit properly, but some have posted they didn't need to do this. Maybe something to do with Stancor, I don't know?? The easiest way to tell if your GPR is bad is using a multimeter, with key on you should have 12 volts at both large terminals on the relay. Below are some photos of my install, as usuall if you have any questions just PM me.
NCH
Notice the wiring studs are pointing towards the rear of the truck, this gives the wires more length to reach.
As I said if you have any questions just PM me.
NCH
NCH
Notice the wiring studs are pointing towards the rear of the truck, this gives the wires more length to reach.
As I said if you have any questions just PM me.
NCH
