Rick's Free Auto Repair Advice

Starter runs continuously

Starter runs continuously

Some Ford owners encounter a situation where the starter run continuously or keeps running even after the engine has started and even after they’ve removed the key from the ignition. At first, this may make you think the starter drive is binding. Or you may think you have a bad starter relay. But in most cases this is caused by binding in the ignition lock cylinder, especially if you’ve lubricated the lock cylinder with any type of lubricant other than graphite or dry Teflon.

Let’s see how the system works.

Click on the image below and download the PDF.

You’ll see that power flows from the battery to the ignition switch. In the start position, power flows to a fuse and then to the transmission range selector (auto trans) or park/neutral switch (manual trans). If the transmission is in either Park or Neutral, power flows to the control coil portion of the starter relay. That’s where the PCM comes into play. It provides the ground to the starter relay control coil. Once grounded the starter relay moves the contacts, allowing power to flow to the starter where the power energizes the pull-in/hold in solenoid that moves the starter drive and connects the starter motor directly to the battery.

So, if your starter keep running, the problem could be stuck starter relay contacts, a continuous ground on the starter relay control coil, or a binding ignition lock cylinder that keeps the actually ignition switch in the START position.

To diagnose the problem, first try rotating the lock cylinder. If the starter motor stops, you’ve found the problem. Try lubricating the lock cylinder with a liquid graphite solution or spray dry Teflon lube. NO OTHER LUBE IS allowed. WD-40, spray silicone, or any other type of all-purpose lube will JUST MAKE THE PROBLEM WORSE. Those lubes attract and hold dirt and turn into sludge. That prevents the mechanism from fully releasing back to the RUN position from START.

If that doesn’t work and you’re sure the lock cylinder isn’t the cause, try swapping the starter relay with another relay with the same part number. If the problem persists, it’s not a stuck relay. Next check for ground at the starter relay control. The relay should only get ground from the PCM when the ignition switch is in the START position. If you find ground in the RUN position, check the ignition switch wiring for your year, model/engine the START wire is NOT hot while the switch is in the RUN position.

Click on the jpg to download the wiring diagram of the starter circuit.taurus wiring diagram, start wiring diagram, won't start

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat


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