Control Board Short

Bob_Engelman · October 1, 2010, 3:49pm

The dishwasher quit running in the middle of a cycle. The start light was red and flashing slow. The pots and pan light remain lit. Water was in the machine. I tried to put the machine into diagnostics mode, but it would not change mode even after powering down and and up. Then I hit the cancel/drain button in an attempt to drain the water. Smoke and light came from the control board area, so I killed the power. I removed the plastic cover, powered up, and hit the drain button again. Some soot is deposited on the plastic cover by the thermal fuse and I can see light & sparks coming from the board, especially one of the relays.

What is the best way to troubleshoot?

Joe_APP_Team · October 1, 2010, 4:49pm

[quote=Bob Engelman;282779]The dishwasher quit running in the middle of a cycle. The start light was red and flashing slow. The pots and pan light remain lit. Water was in the machine. I tried to put the machine into diagnostics mode, but it would not change mode even after powering down and and up. Then I hit the cancel/drain button in an attempt to drain the water. Smoke and light came from the control board area, so I killed the power. I removed the plastic cover, powered up, and hit the drain button again. Some soot is deposited on the plastic cover by the thermal fuse and I can see light & sparks coming from the board, especially one of the relays.

What is the best way to troubleshoot?[/quote]

Bob,

I would check the pump motor and drain pump motor winding circuits.

(just to be sure)

Drain Motor : 4 to 7 ohms resistance
Pump motor : Start winding 6.2 to7.2 ohms resistance.
Run winding 3.5 to 4.5 ohms resistance.

Then, check and clean the touchpad ribbon
And replace the control board.

AP6013337

Good Luck,

Bob_Engelman · October 7, 2010, 11:08pm

Joe,

Today I removed the control board and found a couple hot spots. One of the 4 wires running to the CON2 connector got really hot. The male connector to the hot wire pulled out of the board when I removed the female wiring harness plug. I also removed the board from the plastic holder, and found a lot of black carbon and maybe some solder deposited on the bottom side of the board. Some soot was also deposited by the thermal fuse. The fuse checks good for continuity, so I guess it is still good.

I found the tech sheet which shows 3-7 ohms spec for the wash pump run winding and 6-10 ohms for the aux winding. The tech sheet also shows 16,3 ohms for the drain motor.

What is the best way to check the pumps resistance? Does this require removing the machine and gaining access to the bottom side? Which specs are correct? How do you check run and aux winding resistance? What does the drain motor 16,3 ohm spec mean?

Many thanks for your valuable advice…

Joe_APP_Team · October 8, 2010, 2:49pm

[quote=Bob Engelman;285422]Joe,

Today I removed the control board and found a couple hot spots. One of the 4 wires running to the CON2 connector got really hot. The male connector to the hot wire pulled out of the board when I removed the female wiring harness plug. I also removed the board from the plastic holder, and found a lot of black carbon and maybe some solder deposited on the bottom side of the board. Some soot was also deposited by the thermal fuse. The fuse checks good for continuity, so I guess it is still good.

I found the tech sheet which shows 3-7 ohms spec for the wash pump run winding and 6-10 ohms for the aux winding. The tech sheet also shows 16,3 ohms for the drain motor.

What is the best way to check the pumps resistance? Does this require removing the machine and gaining access to the bottom side? Which specs are correct? How do you check run and aux winding resistance? What does the drain motor 16,3 ohm spec mean?

Many thanks for your valuable advice…[/quote]

Bob,

I’m pretty sure you’ll be fine with a new control board(since the pin pulled out )

For access to the pump and drain motor winding tests, No you do not need to remove the machine.

You need to remove the kick plate panel and the lower access panel, that should give you access to the harness connections to the pump and drain motors and check the resistance(s) on the terminals of the component.

(when you place the meter probes on the two terminals on the drain pump motor you should read 16.3 ohms resistance, (+/- 10%).

You may find it easier to check circuits at the control board.

Across the P3 and P10 wires you should read the Drain Pump motor at 4.2 to 7.0 ohms.

Across the P5 and P9 wires you should read the pump motor at 10 ohms.

I’m using the strip circuit diagram,and you’re correct there are two different resistance readings for the drain pump.

I would go with the numbers I gave you.

Good Luck,

Bob_Engelman · October 8, 2010, 3:45pm

Joe

Resistance across P3 and P10 is 17.3 ohm at the control board connector. Resitance across P5 and P9 is 5.8 ohm. According to the spec sheet, P3 and P10 should read 16,3 ohms for the drain pump. The spec sheet also indicates the wash pump run winding resistance should be 3 to 7 ohms and is checked between P5 and P9. Apparently there is no way to check the wash pump aux winding or capacitor from the control board connectors. Based on the spec sheet, my wash pump run winding checks good and my drain pump check is pretty close.

I also checked the thermal fuse and there is no resistance across it. Is this a good check for the thermal fuse?

Do I need to complete the wash pump aux winding electrical check at the pump? If so, can I access it without removing the machine?

Based on my resistance checks versus the spec sheet, maybe only the board failed and replacing it might do the trick.

Many thanks for your advice…

Joe_APP_Team · October 8, 2010, 4:19pm

[quote=Bob Engelman;285542]Joe

Resistance across P3 and P10 is 17.3 ohm at the control board connector. Resitance across P5 and P9 is 5.8 ohm. According to the spec sheet, P3 and P10 should read 16,3 ohms for the drain pump. The spec sheet also indicates the wash pump run winding resistance should be 3 to 7 ohms and is checked between P5 and P9. Apparently there is no way to check the wash pump aux winding or capacitor from the control board connectors. Based on the spec sheet, my wash pump run winding checks good and my drain pump check is pretty close.

I also checked the thermal fuse and there is no resistance across it. Is this a good check for the thermal fuse?

Do I need to complete the wash pump aux winding electrical check at the pump? If so, can I access it without removing the machine?

Based on my resistance checks versus the spec sheet, maybe only the board failed and replacing it might do the trick.

Many thanks for your advice…[/quote]

Bob,

I’m sure you’ll be fine with the control board and thermal fuse.

The thermal fuse should be a closed circuit, it’s a “one shot” fuse.

I’ll have to remember, about the drain pump winding mis print.

Good Luck,

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Bob_Engelman · October 15, 2010, 2:44am

The control board and thermal fuse arrived today. After reassembly, the dishwasher started without a problem. I checked half-way through the cycle, and smelled electrical burning. I powered down the dishwasher and checked the new board. The board is already a little burned at the P8 connector. P8 got real hot on the old board. The tan wire insulation is a cooked near the board connector but the wire seems good, and the connector plug got real hot when the old board fried. According to the spec sheet the tan power wire runs power from the door switch to the board where it powers a heater element, a wax motor?, and the wash pump.

Is one of these circuits pulling too much power?
Should I try to cut and splice the tan wire and change the female connector where the tan wire plugs into P8?
I forgot to mention the dishwasher went into blinking green light mode a month ago. The spec sheet indicates this failure code is caused by a bad heating element. After the green blinking light failure, I put the machine into diagnostic cycle and the green blinking code has not yet re-appeared.

Should I replace the heating element?

I am running out of options and need to fix this machine.

Joe_APP_Team · October 15, 2010, 1:49pm

[quote=Bob Engelman;287388]The control board and thermal fuse arrived today. After reassembly, the dishwasher started without a problem. I checked half-way through the cycle, and smelled electrical burning. I powered down the dishwasher and checked the new board. The board is already a little burned at the P8 connector. P8 got real hot on the old board. The tan wire insulation is a cooked near the board connector but the wire seems good, and the connector plug got real hot when the old board fried. According to the spec sheet the tan power wire runs power from the door switch to the board where it powers a heater element, a wax motor?, and the wash pump.

Is one of these circuits pulling too much power?
Should I try to cut and splice the tan wire and change the female connector where the tan wire plugs into P8?
I forgot to mention the dishwasher went into blinking green light mode a month ago. The spec sheet indicates this failure code is caused by a bad heating element. After the green blinking light failure, I put the machine into diagnostic cycle and the green blinking code has not yet re-appeared.

Should I replace the heating element?

I am running out of options and need to fix this machine.[/quote]

Bob,

Repair the damaged wire, and terminal.

To check that heater circuit,

Check between the end of the tan wire and the white wire at the door switch, you should read 10 to 30 ohms resistance ( this will be the complete heater circuit) if you are within those readings, then the heater, thermostat and wiring are OK. also check for loose connections at the heater terminals, and repairing the wire should get you up and running.