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Posted by: Vacca Rabite Apr 14 2015, 10:26 AM

I have an old bag of used round relays.
I dont have a 914 handy to plug them into the headlight riser (my usual test).

How can I test them with a multimeter and a small 12 volt battery? I guess I just need the pin out for these things and I should be able to test them pretty easy.

Posted by: r_towle Apr 14 2015, 10:34 AM

Power, ground and a trigger should do it.

Using a lightbulb might be easier to verify it works versus a multimeter.

Posted by: okieflyr Apr 14 2015, 10:35 AM

A 9v battery MIGHT give enough juice to operate it. I'm sure someone can post the pinouts.

I'd have to look at a schematic again to figure it out...

Posted by: type47 Apr 14 2015, 11:35 AM

relay board diagram from workshop manual should help with pin ID's

Posted by: era vulgaris Apr 14 2015, 11:42 AM

Pins 86 and 85 are the relay coil. One gets ground, the other 12VDC. Relays are usually non-polar, so it doesn't matter which gets which for testing. Relays can generally still switch with 75% of their required voltage. Less than that and maybe it'll work, maybe not.

Pin 30 is the pole.

Pin 87a is normally connected, Pin 87 is normally open.

Posted by: stugray Apr 14 2015, 12:45 PM

Put your DMM on Ohms and connect it across pins 30 & 87.
It should read Open or "OL" - Out of Range, etc.
(but you should see continuity across 30 & 87a)

Connect a 12V (9V should work, but no guarantee) across pins 85 & 86 and you should hear it click and the meter will now read less than 10 Ohms. Do that briefly!
If it does not work try reversing the voltage polarity.
As stated above, the coil should pull in regardless of the polarity, BUT many relays have a "reverse EMF diode" inside that will conduct if you apply the voltage backwards so that would prevent the coil from energizing, AND if left that way for too long, you coudl burn up that diode.

Dont worry too much if it works, and the closed resistance does not get below 10 Ohms.
There is not enough current from the meter to "wet" the contacts and make them conduct well.

Posted by: Tom Apr 14 2015, 02:58 PM

I have tried the 9v battery and it will not power the coil enough to close the contacts. Not enough current capacity in the 9v battery.
Typical results from bench testing the round relays with a 12v battery applying power to 85 and having 86 to ground: 30 to 87 with no power to relay = open, no conductivity. 30 to 87 with power to relay = less than 1 ohm.
Tom

Posted by: r_towle Apr 14 2015, 07:12 PM

Stick your tongue across the two prongs when you connect the battery.

Posted by: rhodyguy Apr 15 2015, 12:27 PM

mail your box of relays to a buddy with a running 914 for testing.

Posted by: malcolm2 Apr 15 2015, 12:39 PM

i use the batt from my drill. it is 12v. got one of those?

Posted by: GeorgeRud Apr 15 2015, 12:46 PM

Here's a schematic of the relay:

Posted by: stugray Apr 15 2015, 01:56 PM

I often use a plain old car battery charger for tests like this.

Posted by: Vacca Rabite Apr 16 2015, 02:34 PM

I actually have a 12 volt battery. :-)

But I cheated, visited my 914 today and started testing all my relays. Well, I should say that all the relays I pluged into the headlight motors worked.

Zach

Posted by: McMark Apr 16 2015, 02:52 PM

Here's a more specific diagram.


Attached image(s)

Posted by: barefoot Apr 16 2015, 04:29 PM

While I was going thru circuits individually, I made up a 12V lead using a cig lighter connector with about a 15' lead with alligator clips on both + & - wires, then clipped on at each fuze to test various circuits. 12V provided by my other car.