1999 Ford Mustang car won't start.

Tiny
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  • 1999 FORD MUSTANG
  • 3.8L
  • 6 CYL
  • RWD
  • AUTOMATIC
  • 150,000 MILES
Car won't start. When I turn key it doesn't click or crank over. I can hear fuel pump in gage lights and dash comes on. So I know it's not ignition switch. It's not battery and I've had started test at two different places and both said it was good. All fuses and relays are good. Id really appreciate any info on this problem
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Saturday, March 7th, 2015 AT 5:38 PM

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Tiny
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  • EXPERT
How was the starter tested if it doesn't crank? Why was the ignition switch ruled out? Do you hear a single, rather loud clunk each time you turn the ignition switch to "crank"? Did this start all of a sudden, or did this problem act up intermittently at first? Do you have a digital voltmeter and know how to use it?
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Saturday, March 7th, 2015 AT 5:49 PM
Tiny
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I removed the starter and took it in to be tested. And when I turn key the only thing I hear is the hum from the fuel pump. And because if it was ignition switch my fuel pump wouldn't try to kick on when I turn key
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Saturday, March 7th, 2015 AT 7:35 PM
Tiny
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I removed the starter and took it in to be tested. And when I turn key the only thing I hear is the hum from the fuel pump. And because if it was ignition switch my fuel pump wouldn't try to kick on when I turn key. And it happened all the sudden the car was fine. Packed it for a couple days and went back out to start it and nothing.
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Saturday, March 7th, 2015 AT 7:38 PM
Tiny
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The ignition switch has three or four separate switches in it. If it was just one switch, everything it controls would work at the same time. That means the starter would crank constantly while you were listening to the radio or just driving. Just because you hear the fuel pump, (which is a valuable observation), that has nothing to do with the part of the switch that turns on power for the power windows, heater fan, and radio, and the "crank" circuit has nothing to do with anything else.

On your car the ignition switch is not a common cause of cranking problems, but it should be pointed out that it still has the switch on the lower steering column. Those are adjustable. If the two screws come loose the switch can move down too far to the point where you can't turn the key far enough to get it to the "crank" position. Something similar often happened on the '90s Escorts. At the end of the ignition lock cylinder was a small, wimpy screwdriver tip that turned the switch. If that tip twisted, you'd have to turn the key further and further until the point was reached where it would no longer go far enough for the engine to crank.

The point is, and I don't mean to sound sarcastic, saying the ignition switch is okay is like saying the the radio's power switch must be okay because the power locks work.

In the future, stop here first for my wondrous wisdom before you go through all the trouble of removing the starter for testing. Starter motors are the last thing on the list of suspects for a no-crank symptom. There are a number of things that can happen to a starter motor that will not show up on a test bench. The only accurate way to test a starter is on the engine where it will be under load. That will allow us to test the cables too. Ford is one of the few manufacturers that hasn't switched to a gear-reduction starter like Chrysler had since 1960. The direct drive design draws quite a bit of current and that is not replicated on the test bench. With no load on the bench, your starter will typically draw less than 50 amps. However, when it is trying to spin the engine, it can easily draw over 150 amps. THAT will make a loose or dirty connection show up when just running head lights and power windows will work fine.

The only thing we can assume from external testing is the starter motor spins. There's actually two totally separate motors built into all starter motors. If one part fails, you'll never know that on the test bench. On the engine though, it will crank too slowly, and without getting into the electrical theory, it will draw close to normal current.

Ford HAS switched over to a starter circuit that is similar to what Chrysler and GM use. That isn't better or worse than the multiple designs they had in the past. It's just different now, and it's still pretty easy to diagnose. The entire circuit can be broken down into four parts and each part has a test point at the starter relay. Since you obviously are knowledgeable enough to want to diagnose this, lets start in the middle of the procedure. Be sure it's in "park" because if the engine starts, you'll look funny chasing after your car as it drives away on its own!

The engine can only start if the ignition switch is on. Leave it off for this test. Remove the starter relay from the socket, then use a jumper wire or stretched-out paper clip to connect terminals 30 and 87 in the socket. Post a reply telling me if the starter cranks or it doesn't, and if it cranks at the normal speed. If it doesn't crank or cranks very slowly, turn on the head lights, then try again and watch what happens to the brightness of the lights.
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Saturday, March 7th, 2015 AT 8:23 PM
Tiny
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When I did that the car fired right up! So what do you think it is relay or ignition
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Wednesday, March 11th, 2015 AT 9:38 AM
Tiny
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Well it's not a relay because it swapped it with wiper relay witch is the exact same. So I'm guessing something with ignition? And I really do appreciate the help and the know how.
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Wednesday, March 11th, 2015 AT 10:33 AM
Tiny
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The entire starter circuit can be broken down into four parts, and each one has a test point in the starter relay socket. You just verified two of those parts are working. One is the voltage supply from the battery to the relay contact, and one is the second contact sending current to the starter solenoid. You also verified the starter motor is okay.

That leaves the low-current circuit that turns the starter relay on. One of the two relay terminals goes right to ground so that is the least likely place to find a problem. We'll assume that is okay for now. The voltage to the relay's coil comes through the ignition switch, then through fuse # 6, a 20 amp fuse inside the car, then through the neutral safety switch, and from there to the relay socket. Both switches are relatively hard to get to but luckily the fuse is in between them and that should be easy to reach. Use a test light or digital voltmeter to test for voltage on that 20 amp fuse. There will be two tiny holes on top where you can take the readings. You must find 12 volts on both sides only when the ignition switch is in the "crank" position.

Try that and let me know what you find.
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Wednesday, March 11th, 2015 AT 7:22 PM
Tiny
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I have power at one side of fuse.
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Saturday, March 14th, 2015 AT 4:10 PM
Tiny
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But the number 6 spot has a 15 amp fuse instead of a 30 for some reason
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Saturday, March 14th, 2015 AT 4:53 PM
Tiny
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Voltage on only one side of a fuse means it's blown and must be replaced, unless your probe isn't making good contact. I've been fooled by that before.

You're in the fuse box inside the car, right? That is shown as a 20 amp fuse. What happens after you replace it?
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Sunday, March 15th, 2015 AT 1:22 AM
Tiny
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Yes the one under the dash. And I know it shows a 20 but some reason someone put a 15. And fuse looks good, and I figure there should only be current on the one side because does the current travel through the fuse to the other side? There no way to test it with the fuse still in I have to pull the fuse. And I tested the terminals the fuse plugs into
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Sunday, March 15th, 2015 AT 8:51 AM
Tiny
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A fuse is like a small piece of wire so whatever you read for voltage on one test point, you have to read the same on the other one. You can also pull it out and look at it to see if it is blown.

When my time equals your money, I don't have time to look for service manuals to figure out which fuse to test. Instead, I grab a test light and poke it into the two test points on each one, and I have them all tested within a minute. The next step is to find a point in the middle of an inoperative circuit to see if it's working up to that point. What I had you do by testing the fuse this way was to jump ahead in the troubleshooting process.

You should be testing for voltage but it's only going to be there when the ignition switch is in the "crank" position. What you need to do is touch the test light probe, (or voltmeter probe), to one of those test points, then see if it shows voltage when you turn the ignition switch to "crank". If it does, that proves that part of the ignition switch is working. Now move the probe to the other side of the fuse and do that again. If there's voltage there, the fuse has to be okay.

To clarify, you're testing for voltage AT a point in a circuit. Voltage is electrical pressure. Current is flow THROUGH the circuit, and too much of that is what blows a fuse. If you're using a digital voltmeter instead of a test light, switch it to the 20 volt DC range. That will allow you to measure anything up to 20 volts. Put the black negative lead on the body ground and touch the red positive lead to the fuse's test points. You should find about 12 volts at each point when you turn the ignition switch to "crank". Based on those findings, we'll know in which direction we have to go to next in the circuit.
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Monday, March 16th, 2015 AT 1:04 AM

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