Standard Relay Tester

[sabeo.m]

Hi everyone, does any one know how to tell if the standard black relay has gone bad? Is there a way i can test the relay to see if its still good with out looking else where for the electrical problem: ie, the wiring or fuse box? Thanxs!

[911pcars]

One simple method is a click test.

Here's a schematic of a 1M-1B (1 make, 1 break) relay:



Using test leads, connect source voltage to terminal 86, then ground 85. Once this circuit is complete, the relay should energize, and a "clicking" sound is an indication the contact arm has moved from terminal 87a to terminal 87.

To confirm the contact circuit path (30 ->87) is closing, connect ohmmeter test leads to terminals 30 and 87. When energized, circuit 30->87 should have continuity (0 ohms). With the relay NOT energized, there should be NO continuity (~ ohms)

Hope this helps,
Sherwood

[Paulporsche]

Another way would be to put the suspect relay in a different fusebox socket for another system and see if that item works.

[Phoenix-MN]

Along with testing a relay, does anyone know how much current the blacks relays are rated for?

Thanks

[Bench-Racing]

The relay capacity should be printed or embossed on the top side of the housing. Standard Bosch relays are 30 amp with other units going up to 45 amps. I hope this helps.
Regards,
Charles

[sabeo.m]

I will try these sugestions, Thanxs!

[dshepp806]

As 911pcars noted,....although this could be done while looking at voltage...I don't care much for placing my Fluke on continuity measurements while circuit is hot...look for whatever would be transferred across the contacts (12 volts or grd.) This will tell you if she's working ok.(even contact voltage drop)....checking the coil is a given... again, HOT.

Best,

[911pcars]

Originally posted by dshepp806
As 911pcars noted,....although this could be done while looking at voltage...I don't care much for placing my Fluke on continuity measurements while circuit is hot...look for whatever would be transferred across the contacts (12 volts or grd.) This will tell you if she's working ok.(even contact voltage drop)....checking the coil is a given... again, HOT.

Best,

Doyle,
I agree with your suggestion about testing continuity on "hot" circuits. I should have added this procedure is done on a standalone relay - not plugged into the vehicle circuit. On a standalone circuit test, the 30->87 circuit is not hot, that is unless there's an internal short. A precaution then is to first probe terminals 30, 87 and 87a for source voltage potentially leaking over from the 86/85 voltage path before checking for continuity.

If an ohmmeter connection still creates anxiety, connect source voltage to 30 and a test light to ground via 87. The click should illuminate the test light.

Sherwood

[dshepp806]

Amen!!

Best,