CHT Thermocouple Probe Wiring and Setup
Attached are settings and wiring connections for Cylinder Head Temperature senders. This guide can be used to help if you are experiencing problems or if you suspect your CHTs are reading incorrectly.
Remember to follow these 3 Steps first when troubleshooting senders.
CHT Troubleshooting Steps:
- Are senders wired with the correct polarity? Read this article
- Are senders in the correct channels? Read this article
- Is the correct Type thermocouple selected? Read this article
- A practical test you can do to determine if your CHT is reading correctly. Read this article
There are 2 common types of CHT - spark plug type and screw in threaded type. The threaded probes, also known as CHT Bayonet Probes are typically used on Lycoming engines.
Threaded CHT BAYO Probes:
- Screw 3/8-24 Threaded CHT probes into recesses in cylinders (no washers required)
- Use Thermocouple Channels TC5 through TC8 if you have a 4-cyl engine. Use TC7 through TC12 if you have a 6-cyl engine.
- Remember that some CHTs are type-J thermocouples (these can be used). MGL Avionics supplies only type-K thermocouples
- Remember that with type-K thermocouples that Yellow is Positive and Red is Negative
Wiring Instructions for Type-K Thermocouples:
Note: counter-intuitive colors
Yellow | Positive |
Red | Negative |
Setups:
Select Correct Type in CHT setup (all MGL CHTs are type-K - some other manufacturers also use type-J)