Whats the best way to test my glow plug relay?

[CattleHauler]

I've heard a bunch of different ways...I took my multimeter today and stuck it on the big post with the orange and brown wires going to it and then to a ground and didnt read any voltage? couldnt really make sense of the directions I had...so my question is, which was is the easiest way to check it? Can I just cross 2 of the terminals and see if my glow plugs will warm up in the morning?

Thanks for any input

[Ross01]

I just turned my ignition on, took a test light and tested both of the large posts on the GPR. If both light up, good relay. Only one lights up, bad relay.

[NoRalPh]

Right above ya -> Troubleshooting GPR & GP's

[CattleHauler]

I put a test light on the 2 large posts...one was hot all the time, and on the other one with the yellow and brown wires running to it, once the key was turned, my test light would light up during the click, just for a split second, then nothing...Aint sure if that means its bad or not? Any ideas?

[CattleHauler]

I used the multimeter this time, the large post with the rubber cover on it reads 12+ volts all the time, the two small posts read 1.7V with key off, the one towards back of the truck reads close to 0V with key on, the small post towards the front reads 12+ volts with key on, the other large post still reads 0 with key on and off

Is the relay bad?

[Ross01]

Sounds like it's bad to me. When the relay engages is connects the large post that is hot all the time to the other large post, which then sends power to your glow plugs. Are you having a hard start issue? Also make sure you are testing the gpr and not the intake heater relay

[CattleHauler]

Yeah it's been really hard to start...even when its about 50 outside...and once it does start it blows white smoke like heck for a minute or two then clears itself up...i'm pretty sure im on the GPR, its the one farthest to the back of the truck right? and the intake heater relay is the one a few inches away from it towards the front of the truck right?

[Ouch]

yea its the one closer to the cab. Im just learning with my 7.3 but if the test light only flashes on I would guess the relay is bad... Mine tested fine with the test light but still has hard starts, I now cycle the glow plugs 3-4 times before I turn the key to start, and that seems to help mine..