checking relays

cre · 12-28-2011, 08:48 AM

It depends on the relay but the basic functionality is generally the same... You just need to figure out which pin is which. I found this cool picture sometime back that I've been saving... Just waiting for the day that I could actually point to a graphic when I say: 85 and 86 are the coil; 30 is the constant (power supply or ground); 87a is the "Normally Closed" and 87 is the "Normally Open". When power is applied across the coil the generated magnetic field throws the switch inside opening the circuit between 30 and 87a and closing the circuit between 30 and 87. This is what's generally known as a "Bosch" type relay.

So look at the TEWD and figure out which pins are the coil and which are the switch. Measure across the switch when the coil is powered and when it's not. Which relay is it?

12-28-2011, 08:48 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	It depends on the relay but the basic functionality is generally the same... You just need to figure out which pin is which. I found this cool picture sometime back that I've been saving... Just waiting for the day that I could actually point to a graphic when I say: 85 and 86 are the coil; 30 is the constant (power supply or ground); 87a is the "Normally Closed" and 87 is the "Normally Open". When power is applied across the coil the generated magnetic field throws the switch inside opening the circuit between 30 and 87a and closing the circuit between 30 and 87. This is what's generally known as a "Bosch" type relay. So look at the TEWD and figure out which pins are the coil and which are the switch. Measure across the switch when the coil is powered and when it's not. Which relay is it? __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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