How to Check an Electric Griddle Thermostat With a Multimeter

As an Amazon Associate we earn from qualifying purchases.

How to check an electric griddle thermostat with a multimeter, unplug the griddle, let it cool, isolate the thermostat leads, and use the continuity setting to see whether the contacts close at room temperature. The sources we opened describe the meter readings: a closed path gives an audible signal, and an open path shows OL. They do not cover electric griddles, so the thermostat’s wiring and its temperature range must come from the griddle’s own parts information.

Quick answer

Unplug the griddle and let the plate cool completely. Never test a griddle that is plugged in.
Isolate one thermostat lead, then use the continuity setting across the thermostat terminals.
A beep means a closed path below Klein’s threshold. An OL reading on a path that should be closed means an open circuit.
The sources we opened do not give a griddle thermostat temperature or resistance. A room-temperature check cannot prove the thermostat opens at the right heat.

Electrical safety first

An electric griddle is a mains-powered heater with a hot plate that can burn skin for a long time after it is unplugged. Klein’s MM325 manual says: “Do not attempt to measure resistance or continuity on a live circuit.” It also tells the user to keep fingers away from the metal probe contacts and to use caution with voltages above 25V AC RMS or 60V DC. A plugged-in griddle is a live circuit, so unplug it first and wait for the plate to cool before you open the housing.

Do not open a griddle that has a damaged cord, burn marks, or a smell of burning. Breaker panel and service work belong to a licensed electrician. Check your meter’s CAT rating in its manual and do not use leads that look damaged.

What you are checking

An electric griddle holds a set temperature with a thermostat that opens and closes the heater circuit. The thermostat contacts close when the plate is cool and open as the plate reaches the set point, or the reverse, depending on the design. Fluke’s continuity article defines continuity as the presence of a complete path for current flow, and it says a closed switch that is working has continuity. That is the principle behind this check. The meter can tell you whether the contacts close at room temperature. It cannot tell you the set point.

Tools and setup

You need a digital multimeter with continuity and resistance settings and test leads in good condition. The Klein MM325 manual shows the lead setup: red in the V jack and black in the COM jack. A screwdriver may be needed to access the thermostat terminals, and the griddle’s parts diagram or manual should show which leads go to the thermostat. Label every wire before disconnecting it.

Step-by-step: the continuity check

Unplug the griddle. Remove the plug from the outlet and let the plate cool to the touch.
Access the thermostat. Open the housing only as the manual allows. Mark the position of each wire before you remove any connector.
Isolate one lead. Disconnect one thermostat lead so the heater cannot create a parallel path that gives a false closed reading.
Set the meter to continuity. Klein’s manual says a reading below 100 sounds an audible signal.
Test the thermostat terminals. Touch one probe to each terminal. A closed thermostat at room temperature should beep. An open one shows “OL.”
Switch to resistance for a value. If you need a number, use resistance. Klein’s manual says to start at the highest range and step down for better resolution.
Check to the chassis. Measure from each thermostat terminal to the metal body. The sources we opened do not give a chassis limit for griddles. Treat any low reading to the body as a reason to stop.
Reassemble. Reconnect the leads in their original positions and check that no wire touches the hot plate or the heater.

Reading the results

Meter reading	What the opened source says	What the reading does not tell you
Beep, low value	Klein MM325: resistance below 100 sounds an audible signal.	The temperature at which the contacts open. Not stated in the sources.
OL on a contact that should close	Klein MM325: an open circuit shows “OL.”	Whether the thermostat or the wiring has failed. The source does not say.
Zero or very low reading across an open contact	Fluke: very low or zero resistance indicates a short circuit.	Whether the short is in the thermostat. The source does not say.
Low reading to chassis	Klein MM325 includes a ground symbol but gives no chassis limit.	Whether the griddle is safe. Use the griddle’s documents.

What a room-temperature check cannot show

A thermostat responds to temperature, so a cold check shows only the contact state at room temperature. It does not show whether the griddle holds its set point when the plate heats, and it does not show the temperature scale on the dial. The sources we opened do not describe a heated test for griddle thermostats, so we do not describe one. If the griddle over-heats or never reaches temperature, the griddle’s manual or the maker’s support team is the right place to look for the correct procedure.

Common mistakes

Testing a plugged-in griddle. Klein’s manual says not to measure resistance or continuity on a live circuit.
Leaving the heater connected. A parallel path can give a false closed reading.
Treating a beep as a temperature check. A beep at room temperature shows a closed path, nothing more.
Ignoring damage. A damaged cord or scorched housing is a reason to replace the griddle, not to keep testing it.

How we chose

We chose sources that explain the meter functions and the meaning of continuity and OL readings, and that we could open and read as text on 2026-10-27: Klein Tools’ MM325 manual, the manufacturer’s own document, and two Fluke Learn articles. We searched for griddle-specific guidance. The results were mostly appliance repair and parts-store pages, which we did not use as sources.

What we could not verify

The set point or temperature range of any griddle thermostat. The sources do not give one.
The resistance of any griddle thermostat or heater. No opened source gives one.
The wiring layout of any particular griddle. Check its parts diagram.
The chassis leakage limit for a griddle. No opened source gives one.
The CAT rating of your meter. Check the meter’s listing or manual.

FAQ

Can I check a griddle thermostat with the griddle plugged in?

No. Klein’s MM325 manual says not to measure resistance or continuity on a live circuit.

Why isolate one lead?

If the heater stays connected, it can create a parallel path and give a false closed reading.

What does OL mean here?

Klein’s manual says OL shows when the circuit is open. On a thermostat that should be closed at room temperature, OL means an open path.

Does a beep prove the thermostat works?

No. It shows that the contacts are closed at room temperature. It does not show the temperature at which they open.

When should I replace the griddle?

Replace it if the cord is damaged, if the housing shows burn marks, or if the thermostat reads open and the griddle cannot be repaired from its documents.

Bottom line

Unplug the griddle, let it cool, isolate one thermostat lead, and check continuity at room temperature. A beep means a closed path and OL means an open one, according to Klein’s manual. The sources we opened do not cover griddle temperatures, so the test confirms only the contact state when cold.

Related guides

Sources

Klein Tools, “MM325 Instruction Manual” (manufacturer manual). https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/MM325%20Instructions_web.pdf (opened 2026-10-27)

Fluke Learn, “What is Continuity?” https://www.fluke.com/en-us/learn/blog/electrical/what-is-continuity (opened 2026-10-27)

Fluke Learn, “What is Resistance?” https://www.fluke.com/en-us/learn/blog/electrical/what-is-resistance (opened 2026-10-27)