Thermador gas cooktop - deep questions

Oven/Range/Cooktop Repair
1

Regarding the 12 year old Thermador GGSCV365 cooktop in my house, I have been having issues with the cooktop lately and am thinking about a rebuild to get more life out of it. As a result, I am also trying to understand how the ignitor/flame sensor work. Hopefully I can learn something new on this forum.

Current status of the 5 burner cooktop:

  • When the control knob is turned to high on 2 of the burners, there is no spark until about 7 seconds after gas flow. I assume this is the “flame out” detection generating the spark.
  • One burner sparks/lights immediately after the knob is turned on. We don’t use this burner very much
  • One burner sparks with an irregular cadence and never lights
  • One burner sparks but doesn’t light (gas is detected)

I took apart one of the first 2 burners mentioned above. Igniter was not cracked, but was really dirty. I cleaned the igniter and the wire to the igniter. The igniter clip is rusted and the rubber washer under the igniter was gone. I buffed up the underside of the burner cap. Reassembled the burner but the failure mode continues.

Question #1: Using this single-wire igniter path, the spark module somehow knows that there is no flame (when the gas valve is enabled). How does it detect flame? Somewhere in the cooktop, some logic is being used to detect that there is gas but no flame, but it’s confusing “burner just turned on” vs. “burner was on and lost the flame”.

Question #2: Since we plan to keep the cooktop for a few more years, if I was going to do a refurb on the cooktop, what pieces should I replace to make the cooktop seem ‘as new’? I’m thinking: Igniters, igniter clips and rubber washers. Is that enough? Is the spark module failing or just not getting proper signals from the igniters?

2

Update to my situation now that it appears to be solved. I bought a new ignitor and clip for one burner that didn’t work at all. But, the problem appears to be a grimy connection between the igniter and the wire to the spark module. I took one burner apart, cleaned the burner base and old igniter to remove the grime. The connector on the spark wire that connects to the igniter was pretty gross. I used solvents to remove the cooking goo and then used a pin to try to scratch up the inside of the connector. Using a safety pin stuck in the bottom of the igniter connector, I made sure there was continuity between the pin and the igniter hat once the wire was installed on the igniter. That seems to have solved the problem.

To get at the igniter wire, I used a socket wrench to remove the brass gas pipe in the burner base, then I ran a knife between the larger metal burner plate and the glass cooktop surface. In doing this, you are actually cutting thru a seal that can be reused later. Once you go all the way around, the assembly comes up and you can clean the igniter wire.

I looked into just buying new igniter wires to the spark module, but they are $50 for a set of 5 and I really don’t see the need to buy new wires.

We’re going to keep this Thermador until early next year when we’ll replace it with a Viking rangetop 6 burner unit. :slight_smile: