nobdays

My truck is really hard starting when cold, not sure what to look for, but I read theres a cold mixture heater in my carb it fires right up after its been running for a while. how to test it to make sure thats what it is or any other suggestions to look for to remedy my cold start prob would be appreciated. I posted in pre 84 mine is 83.08 but should be here? My choke is working

slow-mo

My info is based on the 1984+ 22Rs, even though you state that yours is an '83 and posted here.

The Cold Mixture Heater (CMH) device uses a single wire to power the heating element. The ground is through the body. It is controled by the ECM via a thermo-switch mounted on the intake manifold. Right around the spot where the thermostat is.

You can test (correction made:) the circuit one of two ways. One is to disconnect the plug and use a multi-meter to connect the red lead (positive) onto the plug from the wire harness side. Then the black lead (ground) would connect to the body. Run the engine and verify 12 volts at the meter.

Second is to you would back-probe it, through the back of the connector, with a back-probe multi-meter test lead while still plugged in. Red lead (12+) would contact the electrical connector, and ground would go to the body. If you don't have a back-probe test lead, you can use a metal T-pin, the kind you would find a hobby stores, and use it to back probe the connector. Then touch or clip a regular multi-meter lead to the T-pin. Run the engine and verify 12 volts at the meter.

This test can only be done on a cold engine because when the thermo-switch reads a certain coolant temperature (I don't remember what it is), the ECM will turn off the CMH.

To test the CMH itself, uses a multi-meter to test resistance and confirm specs with the repair manual. Another way is just to feel it while the cold engine is running. It should heat up to the touch.