9five1

Is there a way to bench test the DME relay?

Thanks,
~Eric

hderr

Here's the pin resistances, for what it's worth, in ohms except for M = megaohms. O=open, infinite resistance.

.....(-) 30 85 85b 86 87 87b
(+)
30 .....X...O...O...O...O...O
85......O...X...O...O...O...O
85b....O...O...X...O...82..O
86.....O...2M..O...X...O...O
87......O...O..82...O...X...O
87b....O...O...O...O...O....X


Pin 86-85 only conducts in one direction because of the diode.

Hope this helps. I think, it will tell you if the relays are frozen in the closed position and if the diode in the 86-85 circuit is fried.

hd

9five1

Cool.. That's just what I needed! Thanks a ton!

hderr

You're welcome. Let us know what you find out.

hd

hderr

If the resistance readings all check out, here's how to check the two relays inside the box. This test puts power to the relays, so if my directions aren't clear or you don't feel comfortable with doing this, don't do it.

To do this test you will need a 9 volt battery.

There are two relays in the box. We will test each one separately. You can do this by listening for the click of the relay or better is to use your ears and an ohm meter.

Connect the ohm meter (mine has continuity setting, beep) to pins 30 and 87b. Connect the positive side of the 9 V batt to pin 85b using a wire or alligator connector.
With another wire connected to the negative side of the battery, touch the neg side to pin 87. This closes the relay and you should see a big change in resistance on the ohm meter and hear a click. If not, check your connection.

To test the second relay, connect the ohm meter to pins 30 and 87. This is the circuit with the diode in it, so make sure you connect the battery as follows (I don't think connecting backwards will fry the diode, but I didn't try it either, ;-)Connect the positive lead from the battery to pin 86 and touch the negative lead to pin 85. You should see a deflection on the meter and hear the relay close.

Again, hope this helps.

hd

Chris_924s

Great write up- Thanks HD!