Diagnose and fix Ford Focus no start
When you come across a Ford Focus no start condition, check out this common problem. The symptoms are: the Ford Focus cranks but won’t fire up as if there’s a problem with the ignition system.
Check the Ford Focus Ignition Capacitor
The ignition system in the Ford Focus is pretty simple. Power flows from fuse 14 to power the control coil in the PCM power relay. As you turn the key to start the engine, the PCM grounds the control coil. That switches the relay to provide power to fuse 29 which is the power source for all the C.O.P ignition coils. The PCM grounds each coil to make it fire.
The known problem in this setup is the ignition capacitor. The capacitor is used to reduce radio noise interference. The violet wire is spiced into the main power feed to the C.O.P. ignition coils but is known to break and short against the ignition capacitor bracket that is bolted to the engine. This creates a dead short that blows fuse 29. That blown fuse is what prevents ignition and engine start up.
Repair for Ford Focus no start
Start the diagnosis by checking fuse 29 in the underhood battery junction box. If it’s blown, head right for the ignition capacitor violet wire near the connection. It’s located on the passenger side of the engine in front of the valve cover. Check for a short to ground. If you find a broken wire, replace the ignition capacitor and repair the broken wire. Then replace the fuse and start the engine. If it starts, you’ve fixed the problem.
If the capacitor and wire are in good condition and fuse 29 was blown, then the short is in the wiring harness to the C.O.P ignition coils. Unplug the connectors to all four coils. Replace the fuse and try to crank the engine. If the fuse blows, find the short on the supply side of the ignition system. If the fuse doesn’t blow in this test, try checking for a short to ground on the negative wiring harness. If you don’t find a short there, then you have a short-to-ground situation in one of the C.O.P ignition coils.
©, 2019 Rick MuscoplatPosted on by Rick Muscoplat