BOSCH HGS7282UC Self Clean not heating

Joe F

Premium Member
Joined
Jan 5, 2019
Messages
3
Location
Rhode Island
Model Number
HGS7282UC
Brand
Bosch
Age
6-10 years
Morning,

Self Clean feature on BOSH HGS7282UC is not functioning. The door Locks and the broiler ignites and it runs through timed cycle, so oven latch switch should be functioning. However the oven burner does not light, pulled bottom panel and igniter for oven does not turn on. I tried unplugging and same issue. Also verified resistance of oven temp sensor (1083 ohms at room temp, 2 ohm increase with hand on sensor). The oven burner ignites and functions in baking mode, so igniter is functioning. Is there a way to test both the power module and the display control kit, assuming problem is with one of them.

Thanks
Joe
 

Joe F

Premium Member
Joined
Jan 5, 2019
Messages
3
Location
Rhode Island
Rick,

Thanks for responding. I ordered and installed new Module-Power, unfortunately that did not solve the problem. I verified oven temp probe (1066 Ohms at room temp and ~1680 Ohms after heating oven to 350 deg F for a period of time), and oven door lock limit switch return voltage.

I then probed contacts for both igniters. 120 volts being fed to both, but only the broiler igniter has 120 volts on output of contact when in self clean mode. I also probed in bake mode, which works fine and oven burner igniter has 120 volts on contact output as expected.

I am lost for ideas since it should be calling for heat and I have checked the interlock and replaced the logic circuit (function should be part of Module-Power board I believe) which controls the self clean. Chance of getting a faulty Module-Power board seems slim. Any thoughts or items to test?

Replacing the Display Control kit does not seem like a good option since it must be sending single to enter self clean mode since door goes into lock and broiler ignites, unless the logic for the different functions sits in the display Control kit and not the Module-power board.

Thanks
Joe
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
34,316
Location
Murray, Utah 84107, United States
120 volts being fed to both, but only the broiler igniter has 120 volts on output of contact when in self clean mode.
Sorry, I don't know what that says. "Output of contact"?? Unfortunately I'm unable to locate the tech sheet or wiring diagram for that model. On gas ranges the broiler does most of the work in self clean. I believe both turn on at first then the broil flames takes over. The voltage for the igniter comes from the control board in bake mode or self-clean mode. Did you get that board from the link I gave you? Do you have a copy of your tech sheet and can you post t here?
 

Joe F

Premium Member
Joined
Jan 5, 2019
Messages
3
Location
Rhode Island
Had to travel a bit for work. Attached is a copy of the Bosch HGS7282UC/02 wiring diagram. Thanks for the link, I purchased the control module from it, arrived fast and was well wrapped. As for as "Output of contact" goes, I connected common of multi meter to metal frame of range and was able to probe the wires leaving the contactor (relay) connectors.

I first verified both had power at feed and then measured 120 volts when broiler relay closed (also heard and felt it close). The bake igniter relay never closed so voltage on output side stayed at 0 volts during self clean. Tested again in bake mode and measured 120 volts on output side.

So pretty confident igniter and gas valve are fine, but for some reason bake igniter is not getting commanded to close in self clean mode. What led me down this path is after a 4 hr self clean cycle the oven was still dirty like nothing changed, temperature never came up to burn it off. Also baked in the oven without issue for several hours the other day.

Is it possible the display board sends discrete command to the different control relays along with temp set point for the different cooking modes? If so then a faulty display board would explain the issue I am having. Since the relay seems to function, door interlock functions, igniters and gas valve function, and temperature probe resistance looks to also be in spec; cannot think of anything else.

Thanks
Joe
 

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rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
34,316
Location
Murray, Utah 84107, United States
OK, Both igniters get supply voltage from the same board in my link, bake or self clean. If everything works normal in bake mode, the igniter and gas valve are good. That just leaves that board. If you can locate the tech sheet I'm sure there is some kind of service mode you can check for error codes. Part of the problem is I don't know how Bosch operates the bake and broil in self clean. Some, if not most manufactures use just the broil manifold for self clean with the bake turning on intermittently like 2 minutes on, 8 minutes off or something similar.
 
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