TM 9-2320-361-20 Table 2-4. Electrical Troubleshooting (Contd). MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION HEATING SYSTEMS 39. ENGINE MANIFOLD HEATER DOES NOT WORK Test 1. Test engine manifold heater ignition circuit for battery voltage. Step 1. Disconnect lead 55 from engine manifold heater ignition unit. Manifold heater fuel pump is now disabled. Step 2. Set multimeter to a voltage range that will measure 24 Vdc. Step 3. Turn accessory/ignition switch to ON position. Step 4. Push manifold heater switch and hold. Step 5. Touch positive lead of multimeter to contact end of lead 55 and negative lead to frame ground. a. If battery voltage is present, go to test 4. b. If battery voltage is not present, go to test 2. 2-136