Can a Glow Plug Relay be bench tested to see if it works prior to installing. I just bought a new one and it doesn't work on the truck so I need to check if its good or not. Get 12 volts in but no 12 volts out with ignition in start position.

 

Yes, they can be tested when new.

Measure across the two large terminals with an ohm meter and you should get infinity (open circuit).

Then apply 12v positive (+) to one of the smaller primary terminals and ground (-) to the other small primary terminal. This should energize the coil. At this point, measure the resistance (ohms) across the large terminals again. This time there should be a reading, but it should be very very small....about 0.01 ohms or less. This would indicate a good relay.

Be cautious when bench testing a used GPR because they can test good one day and bad the next. This is because the copper ring inside does rotate from time to time so if the ring has some bad spots it won't work as well. Sort of like Russian Roulette.

 

Thanks Greg..........will try