Started 1990 F-150, 5.0L yesterday, then died. When I tried to re-start, heard clicking sounds from starter relay. This has happened before. Replaced starter relay. Also replaced neutral switch on steering column. Old one was jury rigged because the casing was broken loose. Everything back together. Electrical system seems fine, fuel pump engages, radio, lights, etc. Just no starter. Removed the starter, tested it at local auto parts store, fine. Re-installed starter. After all is said and done, I get about 12.5 volts from the negative post on battery or engine ground to the starter relay. When the ignition is on, I get about 5-6 volts at the ignition wire on the starter relay. I get nothing on the starter side of the relay. No spark at all. I can only guess it is somewhere in the ignition (new tumbler and switch), the neutral switch (new) and the starter relay (new). I've also checked the fuse links, working. I have three yellow and one red wire connected on the battery side of the relay. I would appreciate any suggestions. Thank you.

jtpowderkeg

 

That is a good test you did by measuring the voltage when you spring the key to start. Keep that going.

What you need to do first is put the negative on the block like you had it before. Then put the + lead of the meter on the large starter relay post where the battery + cable is hooked to. Get someone to try to start the truck while you are measuring this point.

In the above test, if you get 12 volts, then you know everything upstream to the battery is good, including the battery. If you get 5 or 6 volts, then you know you have a connection problem at the block, at the starter relay, or a cable problem, or a connection problem at the battery terminals, or a bad or dead battery.

So if you got 12 volts, we need to move downstream. The main power wire is one of the smaller wires hooked to the starter relay large terminal. This wire leaves this point and feeds the fusible links you mentioned. These fusible links feed the main power wires for the ignition switch, the headlight switch, and the fuse box.

So the next point we test downstream is going to be decided mainly be what is easiest to get to. If you can get to the yellow wire feeding the ignition switch, this would be the best logical place to measure. We will assume your grounding system is ok, so lets hook the negative test lead to a piece of metal under the dash, and hook the + lead to the yellow wire feeding the switch. Get someone to try to start the truck.

If you get 12 volts, then everything upstream is good to that point. If you get low voltage, then there is a problem from the fusible link to the point where you are testing the yellow wire.

So if you got 12 volts, move you + meter lead to the red/blue wire coming out of the ignition switch. This is the "start" wire that goes to the neutral safety and then the starter relay. Test this wire like the others, when someone tries to crank the truck. If it's low, then you know the ignition switch is bad if the voltage was high before the switch, but low after the switch.

 

Do you mean 12v from the positive post to ground? I would assum so.


When the ignition is on, or turned to the start position?

A meter is fine, but jumpering is quicker. Jumper across the relay with a jumper cable. Does the starter spin? If yes, check the relay circuit. If no, you have a power problem from the battery. Dirty terminals, bad ground, bad battery, bad cables.

Check the relay by using a small jumper from the battery positive to the start terminal on the relay. If the starter spins, you have a problem in the wiring from the ignition switch. If not, you have a relay problem. Most of these units ground using the mounting bolts/screws. Make sure the ground i solid.

With the start wire disconnected from the relay, connect the meter, and turn the ignition to the start position. You should have 12v. If not, check voltage to from neutral start. Then back up from there.

As an aside, you should have no wires connected to the starter side of the relay, only the starter cable. All other wires go to the battery side of the relay. jd

 

Well, everything is up and running. Turns out to be a series of things and thanks to your testing techniques, all is well. Seems the + battery cable was corroded inside the clamp. Not where is connects the the post, but the cable itself. This started the visicious chain reaction. This little problem created a short at times and eventually caused the ignition wire to burn in two, also creating a short, which in turn burned up the starter relay solenoid, and if that wasn't enough, the ignition switch was broke. So, long story short, take care of your battery connections and check your battery cable visually. I tested it with a multimeter and showed both good voltage and good continuity. And that from an 84 year old neighbor walking by on the street. Thanks again.

JT