1988 Ford F-150 iginition problem

THERE IS A STARTER SOLENOID LOCATED UNDER THE HOOD ON THE RIGHT FENDER WELL. CHECK TO MAKE SURE YOU HAVE BATTERY VOLTAGE ON THE LARGE RED WIRE ON THE LEFT SIDE OF THE RELAY. IF SO USE A TEST LIGHT ON THE SMALL TERMINAL, YOU SHOULD HAVE POWER TO THIS WIRE WHEN HELD IN START POSITION HAVE SOMEONE HOLD THE KEY IN START WITH CLUTCH PEDAL DEPRESSED WHILE YOU CHECK FOR VOLTAGE AT THE RELAY WITH A TEST LIGHT. IF YOU HAVE POWER THEN THE SOLENOID IS BAD

Check for power at the small wire of the solenoid during cranking position on the ignition switch. Could a bad ignition switch( not lock cylinder ) or a starter safety switch either neutral safety or clutch disengage switch, depending on trans type.

If the problem is the starter won't crank the engine over, check the small wire at the solenoid (the one from the ignition switch). It should have power when the key is held in crank. If no power there, trace the signal back to the ignition switch-check the neutral safety switch-at the clutch pedal-or the park/neutral switch on the transmission, if automatic. Check if the ignition switch has power out of it on the start wire with key in crank. Use a voltmeter or testlight for checking.

Check the small wire going to the starter relay. It should have 12V when the ignition is in the start position. If it doesn't, you either have a bad igntion switch or a wiring problem from the switch to the relay. If you don't have a volt meter, you can use a 12V test light. Let me know if you need more help.

starter silniod on fender by battery

I'm not thoroughly familiar with your vehicle, but many vehicles have a neutral safety switch that prevents starting when the clutch is engaged and the vehicle is in gear, and that switch can go bad. Assuming you've already ruled out the more common problems, such as battery, starter, cables, and ignition switch, you could check to see if this safety switch has gone bad. Testing requires locating the switch and using an electrical meter to test the connections and the operation of the switch itself. Bring it to a shop if you are not familiar with these procedures. These switches are relatively inexpensive to replace.

if it is standard shift then check the clutch disable switch.... if auto then check neutral safety switch on transmission....confirm power to the starter itself.. report back

W/out knowing details on your vehicle, it makes it very difficult to help. Year? Stick or auto>? engine/trans info. Does it have an alarm installed or a factory security system?

Common checks would be park/neutral switch (Or clutch switch if its a stick), fuses (some cars actually fuse the start signal), old alarm brain that has activated and cut off starter signal, and do the cluster lamps go into SELF TEST and all light up when you turn the key to CRANK. If the lamps do the normal cranking bulb check, then likely your ignition switch is working. depending on the year, ford ignition switches sometymes could be a common problem. But without info to look up a diagram, cant offer more help than generalities

Replace the starter solenoid, I have a 1985 F-150 and did the same thing, it worked, but if it didn't, I was going for the ignition switch next.

The switch is located at the top of the clutch pedal assembly, above your feet. Its a little cramped, but its a simple dc two wire switch, you should be able to check it with a meter for power and to see if the switch does indeed need replacement. If thats the problem, when you see the new switch, you'll know it goes in, very easy. good luck