Something wrong yesterday during baking at 400F. A loud sound “pop” with some blue light around the rear of the range. Then, bake is not working and broil is not working as well. According to the circuit diagram and the electronic oven control(EOC) troubleshooting guide, mostly the EOC or the resistance temperature detector may go bad. I check the breaker box. It looks fine and switch them on and and off to make sure it is ok. The cooktop and everything is ok. The control board is working fine and no fault code or message appeared. I check the terminal block. All wires are fine. No burning. By using the multimeter, I have the following measurments:
Bake Element is 22 ohm. Broil Element is 19 ohm. The temperature sensor is 880 ohm at room temperature. It seems those figures reflecting that they are fine. No burning sign on all terminals.
Refering to the control board and circuit diagram;
With power on (plugged), L1/Ground(G) is 120V. L2 IN/G is 120V. L1/BAKE is 120V. L1/BROIL is 120V. L2 IN/L2 OUT is 120V. L2 OUT/G is 2V. BAKE/G is 2V. BROIL/G is 2V. BAKE/BROIL is 0V. L1 is black. L2 IN is red. L2 OUT is orange.
With BAKE on (350F) Preheat after “click”;
BAKE/L1 is 0V. BROIL/L1 is 0V. BAKE/G is 120V. BROIL/G is 120V. BAKE/BROIL is 0V. BAKE ELEMENT TERMINALS is 0V. BROIL ELEMENT TERMINALS is 0V. L2 OUT/G is 120V. L2 IN/L2 OUT is 0V.
With BROIL on after “click”;
BAKE/L1 is 0V. BROIL/L1 is 0V. BAKE/G is 120V. BROIL/G is 120V. BAKE/BROIL is 0V. L2 IN/L2 OUT is 0V. L2 OUT/G is 120V. All Bake/broil element terminals has 0V.
Is it wrong with heating elements or the temperature sensor or the control board? I already ordered the sensor because it is not expensive. Can I have some advise or suggestion? Thank so much.
Unplug the unit.
Remove one wire from each oven element and measure it for resistance to ground. Both should be infinite resistance (open).
Unplug the unit and check that one of the wires has not shirted to the frame. Also if you saw a blue flash there should be some evidence of it, either some smoke residue or a arc/weld mark.
The way I interpret the wiring, the board has relay/contacts for L2 IN/OUT. It also has a relay for L1/Bake and one for L1/Broil
When set at OFF you see 120 across the L2 IN/OUT relay.
You should not see any voltage here because the Bake and Broil elements are open so you should not have a circuit path.
Thank you so much for your prompt reply. The top elements are working fine but there is something unusual; the element should turn red hot gradually but now it turns on red hot immediately when I turn the knob to high. Also the element normally should cool down in about 10 minutes, right now it takes much longer to cool down, after I turn knob to OFF. I follow what you say to set the bake ON when the top elements are ON. I don’t see any change to the top elements.
For the oven elements wires, I do the continuity test. They have no continuity(no buzz sound from the meter).
I check all wire terminals. No signs of burning. But I found some charred/smoke area around the big relay(for the L2 IN and L2 OUT) on the control board. As I said, we saw blue light around the rear top of the range. The control board is exactly at the top of the range. I wonder so much the light and the “pop” sound come from the burning relay. What do you recommend? Thank.
Unplug the unit
I would remove L1 and L2 IN at the control board.
Tape them up so that they cannot short to anything.
Plug it back in.
Now try the stove top element test.
If the stove top elements now run OK, odds are high that the control board is shot.