Thermador Range gas burner won't light

[swedespeed]

Hi all! Thanks in advance for reading about my issue. My parents have a Thermador Range Model PCG486GD/02. It has 4 burners on the left, a griddle in the middle, and 2 burners on the right. I've repaired it once already (1 unrelated burner not sparking).

Now, the two left-most burners are sparking nice and strong but are not lighting. The problem seems to be no gas flow. I can't hear the gas hissing out of the burner and I can't smell any gas either. The other 4 burners work fine. I'm thinking the solenoid gas valve, which would be this part. Do you guys agree? Also - and this may be a dumb question - but there's one solenoid for every burner, right? So I'd need 2 of them? I guess it seems unlikely that both solenoids would fail at the same time. Maybe it's something else?

Any other ideas? Thank you!

[16345Ed]

Make sure all burner ports are clear usually just a good cleaning is needed if you are getting proper spark. 

[swedespeed]

3 minutes ago, 16345Ed said:

Make sure all burner ports are clear usually just a good cleaning is needed if you are getting proper spark. 

OK thanks - do you mean just removing the burner caps and inspecting/cleaning from above? Or something internal? Also - not to doubt you - but the stove is kept exceptionally clean at all times. Could a dirty port really result in zero gas flow? There is no flow whatsoever.

[16345Ed]

If not a port the orifice itself could be clogged. 

[AccApp]

On those xlo burners you should hear a "clunk" when turning the burner on, that's the solenoid engaging. There are switches on both burner valves (potentiometers) that give a signal to the simmer controller to open the gas valve. If both burners stopped functioning at the same time I'd guess the simmer controller failed, those solenoids are pretty trouble free.

[swedespeed]

10 hours ago, AccApp said:

On those xlo burners you should hear a "clunk" when turning the burner on, that's the solenoid engaging. There are switches on both burner valves (potentiometers) that give a signal to the simmer controller to open the gas valve. If both burners stopped functioning at the same time I'd guess the simmer controller failed, those solenoids are pretty trouble free.

Awesome thank you! To clarify, which of these is the simmer controller? #1,   #2,   #3

[swedespeed]

Sorry, I gave some misinformation. When turned to "light", the left 2 burners don't spark either. The control knob does absolutely nothing, no spark, no gas. If I turn on either of the right 2 burners, all 4 burners have a strong spark (but the left still don't light). Does this change the diagnosis?

[Budget Appliance Repair]

No, only the left two burners have the XLO feature, when the XLO burners where working correctly they would spark all 4 burners at the same time also.

So you problem is most likely the XLO simmer control module and/or the control switches for the 2 XLO burners but if both quite working at the same time then most likely not the control switches but the XLO simmer control module.

[swedespeed]

3 hours ago, Budget Appliance Repair said:

No, only the left two burners have the XLO feature, when the XLO burners where working correctly they would spark all 4 burners at the same time also.

So you problem is most likely the XLO simmer control module and/or the control switches for the 2 XLO burners but if both quite working at the same time then most likely not the control switches but the XLO simmer control module.

Got it, thanks. I will pull the components and test/inspect with my multimeter

[AccApp]

23 hours ago, swedespeed said:

Awesome thank you! To clarify, which of these is the simmer controller? #1,   #2,   #3

It's neither one of those, #2 is just a spark module, #3 is the potentiometer and #1 is an oven control board.

Trace the wires from the potentiometer and they will lead to the simmer controller.

[swedespeed]

Just now, AccApp said:

It's neither one of those, #2 is just a spark module, #3 is the potentiometer and #1 is an oven control board.

Trace the wires from the potentiometer and they will lead to the simmer controller.

Thank you, I'll just open it up and see if I can find it. Appreciate all your help!

[AccApp]

Hold on, it looks like the simmer controller is the #1. Is this part of  a range? Or just the surface burners with no oven?

[swedespeed]

surface burners, no oven

[AccApp]

In the trade, we call this a "Rangetop"

[AccApp]

Similar to a cooktop but the knobs are on the front, on a cooktop the knobs are on top and it just drops into a cutout in the counter.

[swedespeed]

3 hours ago, AccApp said:

Similar to a cooktop but the knobs are on the front, on a cooktop the knobs are on top and it just drops into a cutout in the counter.

 

3 hours ago, AccApp said:

Similar to a cooktop but the knobs are on the front, on a cooktop the knobs are on top and it just drops into a cutout in the counter.

Got it, thanks!

[T38]

I know I'm late to the party, but the guests here seem pretty sharp.

The left rear burner sparks but doesn't light, no "clunk/gas." Infinite resistance at the tabs for that solenoid , so I'm assuming that that solenoid is bad.

What I'm concerned about is that the wires that connect to that left rear solenoid show around 30v ac even when the potentiometer is turned off, when I rotate it to the on position it jumps up to around 50. This happened even after I swapped the front and rear potentiometers. I crossed the leads such that the left rear potentiometer was connected to the left front solenoid (the operating one) and it makes the "clunk," appearing to operate fine. Is it possible that a constant low voltage (below the threshold to operate the solenoid) burned up the solenoid for the left rear over time? I don't want to just solve the symptom if there is a underlying issue. What am I missing? Thanks a ton in advance.

 

(the first hoegaarden is on me)

[T38]

A little more data:

I took the connector off the left rear potentiometer and it seems like the blue wire on the far left edge of the connector is the same blue wire that goes to the top ear of the solenoid for the left rear burner (duh, I guess, but I don't have a wiring diagram.) What was of interest is that the tab on the connector was showing around 30vac. Unless that blue wire goes somewhere else before heading to the solenoid, possible the connector has leakage????

If so, can I replace the connector? Anyone have experience tracking down all five wires (I really don't want to cut and splice.)

Thanks again.

[T38]

It's quite humbling when you have a EE degree (granted it's 35 years old) and you don't know how to read a multi-meter. I'm guessing that I was measuring ghost voltage as when I switched to an old, cheap analog multimeter it read almost zero. I'm hoping that just a simple solenoid swap will fix it. Your chances of a hoegaarden are rapidly diminishing.

[T38]

Solenoid replacement worked. My after-action report follows (disclaimer-I'm a hack and take zero responsibility for any damage done on my account):

The following only applies if only one burner failed.

If the igniter fires but no smell of gas:

clunk heard? Y/N

• Y: all I can think of is the valve directly behind the controller knob being bad as it sounds like the solenoid is operating
• N: the circuit is comprised of the simmer controller, the potentiometer, the solenoid, and the wires. Probably the easiest way to troubleshoot is to switch the front solenoid lead wire pair to the rear solenoid, and the rear solenoid lead pair to the front solenoid. (There is no polarity so it doesn't matter if you switch positions within the pair) If the previously inoperable solenoid works, then the problem lies in the signal from the simmer controller (that can be checked by looking for 50Vac across the ("solenoid" and "solenoid return") tabs on the simmer controller itself, when the knob is turned on); the potentiometer (take off the plastic connector on the pot and look for open circuit between the outboard metal strips on the potentiometer if it is in the off position, and a short circuit with it in the on position); or the connecting wires (check for continuity, the wires are clearly, if microscopically, labeled.) As an aside, the previously operable solenoid probably won't work. If the previously inoperable solenoid still doesn't function, the solenoid is most likely bad. I suppose a more direct route is to just check the resistance across the solenoid leads, it should be around 1.7 k ohms. Mine read open.

Swapping out the solenoid once you have everything torn apart isn't that hard, make sure that the leads are rotated to the proper position prior to installation as they can't be rotated once installed. Back up the brass gas fittings on the solenoid as you tighten the nut holding the gas tubes on either side of the solenoid. My advice is try to find and keep a trustworthy repair guy. If I found a guy I trusted I would have happily paid him at least 500 for this job. I have been fleeced by too many guys now, though, so I fumble f&@$%ed my way through this. If you do this I suggest being prepared to replace/repair the leads from the spark controller to the igniters as they take a thermal beating. Prior problems with them caused constant igniter clicking. Finally, a huge shout out to those guys that donate their time to help guys like me out. Whether these posts of mine are any help or not, I did it out of guilt for all the help I've gotten, and the little I've offered.

Cheers

[YanB]

On 12/2/2020 at 3:33 PM, T38 said:

Solenoid replacement worked. My after-action report follows (disclaimer-I'm a hack and take zero responsibility for any damage done on my account):

The following only applies if only one burner failed.

If the igniter fires but no smell of gas:

clunk heard? Y/N

• Y: all I can think of is the valve directly behind the controller knob being bad as it sounds like the solenoid is operating
• N: the circuit is comprised of the simmer controller, the potentiometer, the solenoid, and the wires. Probably the easiest way to troubleshoot is to switch the front solenoid lead wire pair to the rear solenoid, and the rear solenoid lead pair to the front solenoid. (There is no polarity so it doesn't matter if you switch positions within the pair) If the previously inoperable solenoid works, then the problem lies in the signal from the simmer controller (that can be checked by looking for 50Vac across the ("solenoid" and "solenoid return") tabs on the simmer controller itself, when the knob is turned on); the potentiometer (take off the plastic connector on the pot and look for open circuit between the outboard metal strips on the potentiometer if it is in the off position, and a short circuit with it in the on position); or the connecting wires (check for continuity, the wires are clearly, if microscopically, labeled.) As an aside, the previously operable solenoid probably won't work. If the previously inoperable solenoid still doesn't function, the solenoid is most likely bad. I suppose a more direct route is to just check the resistance across the solenoid leads, it should be around 1.7 k ohms. Mine read open.

Swapping out the solenoid once you have everything torn apart isn't that hard, make sure that the leads are rotated to the proper position prior to installation as they can't be rotated once installed. Back up the brass gas fittings on the solenoid as you tighten the nut holding the gas tubes on either side of the solenoid. My advice is try to find and keep a trustworthy repair guy. If I found a guy I trusted I would have happily paid him at least 500 for this job. I have been fleeced by too many guys now, though, so I fumble f&@$%ed my way through this. If you do this I suggest being prepared to replace/repair the leads from the spark controller to the igniters as they take a thermal beating. Prior problems with them caused constant igniter clicking. Finally, a huge shout out to those guys that donate their time to help guys like me out. Whether these posts of mine are any help or not, I did it out of guilt for all the help I've gotten, and the little I've offered.

Cheers

Hi T38 thanks for sharing the detailed diagnosis and notes, really appreciate it!

I am currently having problems with my thermador rangetop also. No spark for all 4 igniters, which makes me think the spark module is probably dead. But I also suspect the controller board is bad also since I didn’t hear any click sound from the solenoids. Is there a way to check and confirm the defect control board before I spend couple hundred dollars on a new board?
 

BTW, I found a burn hole on the potentiometers and I replaced them with brand new ones, but still no luck..

[Tiretyme]

Hey guys, all of a sudden my Thermidor 5 burner cooktop igniters quick working along with the two burners on left side. There is no clunking noise or any noise when I turn on. The center and both right side have gas but must use a lighter to ignite them.

Do you access these solenoids from underneath? 
 

Other than unplugging unit and turning off gas anything I need to look out for? Where does one purchase these solenoids?

Thanks in advance for any direction. I do have an electronic multimeter and am fairly proficient with it. 
 

Thanks in advance, Joey

[BC20]

A new comment on an old thread from T38 - I thought the Solenoids are DC Voltage.  I checked them on mine since the XLO is not working and found 10.4V DC on the leads to the Solenoid coming from the SImmer controller with the knob OFF and no change as the knob is rotated.  I am assuming the sequence of action if everything was working fine is that the Pot behind the knob sends the signal to the Simmer Controller, which in turn energizes the Solenoid and sends Line Voltage to the Spark Controller.   If I am not getting any gas flow from the Solenoid or not hearing a clunk when I turn the knob I am assuming it could be either the POT or the SIMMER CONTROLLER that has gone bad - but since it's happening on both XLO burners as somebody suggested it's most likely the SIMMER CONTROLLER.  Is there any way to test the POT to know if it's good or bad without having it in the circuit? 

[BC20]

Hi just a quick question to the other posters on this thread - this is an old issue for my simmer (XLO burners not working)  and I gave up on it before but have now narrowed it down to a bad potentiometer but for the heck of me I cannot figure out how to remove and replace the potentiometer.  I purchased a new one and have it ready but haven't figured out how to get the old one out.   Can anybody help me here - either a step by step how to or if anybody has any pictures - I just need to know how much of the unit do I have to dismantle to change the dang pots...the range is a Thermador PCG486GD (circa 2005 and am original owner)..can add pictures if needed..

 

@YanB - you mentioned in your post that you replaces the potentiometers - very interested in if you could provide any assistance...

[Nathaniel Peterson]

7 hours ago, BC20 said:

Hi just a quick question to the other posters on this thread - this is an old issue for my simmer (XLO burners not working)  and I gave up on it before but have now narrowed it down to a bad potentiometer but for the heck of me I cannot figure out how to remove and replace the potentiometer.  I purchased a new one and have it ready but haven't figured out how to get the old one out.   Can anybody help me here - either a step by step how to or if anybody has any pictures - I just need to know how much of the unit do I have to dismantle to change the dang pots...the range is a Thermador PCG486GD (circa 2005 and am original owner)..can add pictures if needed..

 

@YanB - you mentioned in your post that you replaces the potentiometers - very interested in if you could provide any assistance...

Usually you have to take the burner knobs off and some or all of the screws behind the burner knobs. Possibly a couple screws when opening the oven doors. Then lift up on the building nose ( metal housing that burner knobs hooked up to) and be careful of any connectors attached for indicator lights on bullnose if any. Then the molex slides off the potentiometer and the potentiometer just pulls off. Make sure you pull straight off with a firm grip but not extremely hard. Make sure it's lined up correctly when putting the new one on so you don't snap the board on it. Take pictures for reference for reassembly. Some of the screws behind burner knobs may or may not have to come off just be careful of any attached wires. Easy to have a helper hold stuff for you to maybe not have to take apart everything. Good luck.