Bunt food the 9 inch burner stays on hi and will not modulate its heat setting ( it comes on and stays on ) . this element has the option of being a 6 inch , or nine inch. the element will shut off when turned off .

SEE PICS Or Oven safety valve needs to be checked with multi meter ohms / voltage
ALSO Test the Burner Heating Element
The stove's burner heating element is a coil of metal sheathed in an insulator. Electrical current travels through the element. Resistance to the passing of electrical current causes the element to heat up. A precise temperature cannot be set for a burner, instead it is turned on and off repeatedly by the control to the achieve an average temperature. When it is set to a low temperature, the element is cycled on and off more frequently. For high temperatures, the heating element is energized longer with fewer on and off cycles. Some burners have two elements, with the second only being used only for high heat settings.
Before testing the heating element, unplug the appliance or shut off the power at the fusebox orbreaker panel to avoid an electrical shock hazard.
When a burner does not heat at all, or only heats up to a lower than expected temperature, the problem is likely to be with the heating element, the temperature control switch, or the wiring. If it only heats at the highest temperature, the problem is with the control or an electrical short, not the burner. If the burner works only intermittently, the problem is likely in the wiring or connectors. To test the heating element, try the following steps.
First, disconnect the heating element from the stovetop. In most cases, this is done by lifting up the burner on the side opposite of the terminals (the part of the burner that disappears under the stovetop). Remove the decorative ring.
Inspect the style of connection. If the burner element has visible blades that fit into the receptacle block, pinch the block with one hand, and pull the heating element free with your other hand. If the terminal block clamps over the element, the housing must be removed and the burner wires disconnected. Unsnap the metal piece or remove the screw that secures the receptacle block and then disconnect the element.
Inspect the heating element. If you find bubbles, warping, or damage to the insulation sheath, the burner must be replaced. If the terminals are dirty or corroded, this can cause poor temperature control, intermittent problems or complete failure to heat. Clean the terminals with steel wool or very fine sand paper to restore good conductivity. Test the resistance of the heating element using a multi meter. Set the multi meter to the ohms setting X1 and touch one probe to each of the terminals. A normal reading is typically somewhere between 20 and 120 ohms. The exact reading differs by manufacturer and mode. If the meter reads infinite resistance or the other extreme of the scale, zero resistance, then the element is damaged and should be replaced. If the measured resistance differs significantly from the expected range, the element is probably bad, but if possible, determine from the manufacturer what the actual resistance should be.
To test for a grounded or shorted element, touch one probe to the surface of the burner and the other probe to each terminal in turn. If you get continui

This happens when one of the infinite switches short out. The indicator lamp will remain on even though none of the elements are heating up. To figure out which one is defective, gain access to the rear of the switches and remove the wire going to terminal P (Pilot) Restore power and see if the light is out now. Keep doing this to the remaining switches until you find the one where the light stays out with the wire removed after power is restored. Supply model number and we will supply the part number for the infinite switch. Be sure to let us know if it is the 6 or 8 inch burner switch. Good Luck and be careful. Eric

The elements DO BURN OUT. Replace it.

Often you can see evidence of a hot spot on the element where the final failure occured, but not always.

You may have a cracked element, they expand when heated and cause a separation in the element. You really have to put a voltmeter on it to test it under load. If the voltage remains constant while the element is heating and cooling, then indeed you have a bad element.

If you don't have a voltmeter, or don't want to perform this test, buy a heating element and replace it, if you have the same problem, you'll have a spare element

Sounds like you need to replace the burner control (part # WB23K5053)

I have the part. New in box.

Sounds to me like the RF switch is bad.
Eddie Rentas
Tupper Lake NY

if the 9inch dont cycle off and on like the others and the 6 dont work at all replace the element

I have had this same problem on the JP350.

I have replaced the switch several times, and am now tempted to replace the heating element and the switch the next time it becomes constant (currently, it is intermittent... which has led to some burnt food).

The problem is the pot(s) is too far from the heat. Jenn-air needs to make a burner cover that is closer to the burner for boiling water...