how to test relays
how to test relays
i want to see if these relays are working properly i have 2, how can i test them.
http://relays.tycoelectronics.com/datasheets/VF28.pdf
http://relays.tycoelectronics.com/datasheets/VF28.pdf
There are two types shown. You can tell if it's single pole, double throw (SPDT) or single pole, single throw (SPST) by the pin count.
~~~~~~~~~~~~~~~~~~~~~~~~~
SPDT (5-pin)
pin 30 to pin 87A: near zero resistance
pin 30 to pin 87: near infinite resistance.
Then apply 12v, + to pin 85 and - to pin 86:
pin 30 to pin 87A: near infinite resistance.
pin 30 to pin 87: near zero resistance
~~~~~~~~~~~~~~~~~~~~~~~~~
SPST (4-pin)
pin 30 to pin 87: near infinite resistance.
Then apply 12v, + to pin 85 and - to pin 86:
pin 30 to pin 87: near zero resistance
~~~~~~~~~~~~~~~~~~~~~~~~~
SPDT (5-pin)
pin 30 to pin 87A: near zero resistance
pin 30 to pin 87: near infinite resistance.
Then apply 12v, + to pin 85 and - to pin 86:
pin 30 to pin 87A: near infinite resistance.
pin 30 to pin 87: near zero resistance
~~~~~~~~~~~~~~~~~~~~~~~~~
SPST (4-pin)
pin 30 to pin 87: near infinite resistance.
Then apply 12v, + to pin 85 and - to pin 86:
pin 30 to pin 87: near zero resistance
If you're in doubt just swap the relay with a known good one. Take the relay you're in doubt of and make it your fog lamp or fuel pump relay and you'll know right away. That's all I ever do and still make money at work.
Originally Posted by 67cobain94
If you're in doubt just swap the relay with a known good one. Take the relay you're in doubt of and make it your fog lamp or fuel pump relay and you'll know right away. That's all I ever do and still make money at work.

well i don't know if im doing correctly as you explained, but using a multitester and contacting they way you say i get 00.5 or less no clicking sound coming from the relay. tester set to V DC with black lead to 'COM' and red lead to 'V'
Last edited by Rob99; Aug 6, 2005 at 12:04 PM.
Right. You will need to apply 12V DC from a power source such as a battery or a group of batteries. At the truck, I use clip leads from the truck's battery. When bench testing in the house, I use a simple battery holder from Radio Shack that holds eight 1.5V AA batteries. It looks something like this:
Thread
Thread Starter
Forum
Replies
Last Post
FireRanger
General Technical & Electrical
50
May 17, 2025 12:53 PM
FMD
General Technical & Electrical
4
Dec 8, 2005 04:41 PM




