How to Troubleshoot Your Cruise Control Transducer
A misreading cruise control transducer can cause a drag if you want to drive on the highway at a certain speed. This transducer (also called a vehicle speed sensor) is a device that reads your car's speed and translates it to a manageable data input for your control unit. If you drive at, say, 65mph on the highway and you notice other vehicles at 55mph getting past you, then it is a sure sign that your transducer needs troubleshooting. If you want to drive with accurate speed again, then check your speed-reading device first before unnecessary replacement cost you bucks.
Difficulty level: Easy
- Digital volt-ohm meter
- Screwdriver or wrench (for fastening connections)
Troubleshooting for power
Step 1: If your transducer has no 12-volt power, check the fuse and the brake light switch. Make sure that the connectors are attached to the terminals.
Step 2: If your engine does not accelerate, check the orifice tube. Also, check if there is a leak in the engine vacuum. If your engine has a vacuum, make sure that the hoses and fittings that connect back to the transducer are securely attached. If your engine has no vacuum, check the engine manifold vacuum instead.
Troubleshooting for performance
Step 3: See if the vacuum hoses are not pinched, disconnected, or damaged. Also, ensure that throttle linkage is not bound or impeded.
Step 4: Drive the car at 55mph. Note that the speed reading changes 1mph for every 1/4 turn of the wheel. Check if the cruise speed is accurate for the engagement speed. If the cruise speed is below the selected speed, screw the orifice tube of the transducer outward. If the cruise speed is above the selected speed, screw the orifice tube inward.
Troubleshooting for reading accuracy
Step 5: Detach the 2-pole wire that connects the transducer to the entire system. Connect an ohmmeter between the dark green (or white) and black wires. See if the reading is between 180 and 250 ohms. If the reading is 0, you must look for a shorted coil; an infinite reading indicates an open coil. Replace the device if the proper reading is not attained.