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Discussion Starter · #1 ·
hey guys how is it going... i just got a call from my bro-in-law. his 95 yj wont start. i havent been over to check it out so bear with me, this is all i was told...hey took the starter to get tested and it's fine, swaped out another battery and still the same thing. he says all he gets is a click when he turns the key... any suggestions? i will fill in some of the details when i stop by later on today. just looking for where to start. thanks in advance
 

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Re: yj question.. kinda vague

Starter selinoid. Check all battery to starter connections. Could be enough juice getting through to click the selinoid...but not enough spin the starter. Take a block of wood or dowel and give the selinoid a good whack or two...
 

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Discussion Starter · #3 ·
Re: yj question.. kinda vague

that's kinda what i had in mind. i'm going to check it out later today.. do you happen to know if 4 cyl. run an igintion seloniod that might go bad?
 

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Re: yj question.. kinda vague

Turn on the headlights and try to start it. If the headlights don't change it's either a bad solenoid or connection between the solenoid and he starter motor. Or it could be a bad ground cable connection at the block.

If the headlights dim or go out, it's a bad connection at the battery or the hot side of the solenoid.

Usually if you hold it in the start position for a few seconds the bad connection will get hot enough that you can feel it with your finger.
 

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Discussion Starter · #5 ·
Re: yj question.. kinda vague

good info, i'll try it out when i go over later...just asking... what if there is no click when he turns the key??
 

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Re: yj question.. kinda vague

If there's no click there are quite a few possibilities. The solenoid could be bad, or a connection could be bad between the solenoid and the switch, or the switch could be bad, or there could be a bad connection between the swithc and the battery, or there could be a bad ground connection.

It's best to narrow down the possibilities logically, rather than try to check every one.
 

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Discussion Starter · #7 ·
Re: yj question.. kinda vague

yeh that's what i had going through my head... well thanks a bunch guys. i will go at it later.
 

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Discussion Starter · #8 ·
Re: yj question.. ((updated))

ok, so i finally got around to checking out my bro-in-law yj... he ended up exchanging his starter since it was still under warranty, replaced the ground cable from battery to engine block. but still no crank. when he turns the key it clicks, like a bad solenoid.. but this is his second reman starter in a month. and all the fuses under the hood are fine.. any thoughts?
 

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Re: yj question.. kinda vague

Just an FYI to CJ owners, the YJ starter solenoid is part of the starter, not mounted on the fender.
 

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Re: yj question.. ((updated))

im not totally memory familiar with the way the 4.0's have their starter circuits laid out.

the 4.2's have 2 wires that go to the external, ford style starter solenoid. if one is not connected or they are switched, you'll have starter problems. chase the 2 14ga wires back using a schematic and you could find the problem.
 

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Re: yj question.. ((updated))

If the click is coming from the area of the starter, it means that the starter solenoid is actuating, so that takes all questions about fuses, ignition switch, neutral safety switch and the low-current control wiring out of the problem. Here's what you need to do:

Have someone turn the key to the start position, so that you hear the click. Verify that it's coming from the starter solenoid.

OK, with the key still held over, the starter motor should run. Since it isn't, the flow of current is being interrupted somewhere. Remember that the flow is a complete loop (a circuit!) from the battery to the solenoid to the starter motor to the block and back to the battery. While you're running these tests, have your assistant release the key after each test until you're ready for the next one. That will prevent overheating the solenoid.

Jim Lou's Logical Electrical Fault Detection Procedure

REMEMBER: While you're fooling around here, the engine could crank up at any time, so keep tools, test leads and body parts away from anything that might move if it does start.

You'll need a voltmeter or preferably digital multimeter. A basic DMM from Radio Shack will work fine. What you need to do it put the probes of the voltmeter on opposite sides of every component and junction in turn. Start at the battery + terminal. Put one probe on the post and the other on the cable clamp. The reading should be zero.

Next put the probes on the cable clamp and on the input stud of the solenoid, then on the solenoid input stud and the output stud, the output stud and the starter lug, the starter lug and the case, the case and the engine block, the block and the ground cable attachment bolt, the bolt and the cable terminal, the terminal and the ground battery clamp, the cable clamp and the ground post.

Somewhere in this odyssey you will get a reading of nearly battery voltage (Whether the reading is positive or negative is immaterial; it's a function of which probe is on which component.) Between the probes is where the current is being stopped.

To speed the process you can span several components at a time. When you find the bad section of the circuit, you can pin down the failure point by moving the probes closer together, until there's only one component or connection between them. That is the bad spot.

(And don't forget to test between the battery terminals themselves. A battery can develop a bad connection internally, and this test will find it. Here you should have twelve volts. If it drops way down when you try to start the engine, the battery is bad or terribly discharged.)

This technique will quickly locate a failure, but it can also be used to find poor connections. If the starter is operating, but slowly and the battery voltage is normal, a dirty, loose or corroded connection is probably at fault. When the probes straddle that spot, you will get a significant reading on the DMM. In a 12-volt system, anything more than a tenth of a volt or so is significant in a cable, and connections should only show a few thousandths of a volt. When you place the probes across the starter input lug and the starter case you should have battery voltage, since that's the component where the work is taking place.

This technique will work for any component in a DC electrical system. Headlights dim? Turn them on and check the voltage between the hot and ground terminals on the bulb. What you get there should be close to battery voltage. If it's a significantly less, test between the hot terminal on the bulb and the battery. There are a lot of components between the probes now, so there may be a half volt or so show up. If there's more, go between the bulb and the dimmer switch, then between the input and output terminals of the dimmer, then between the dimmer and the light switch. It gets tricky getting to all those places in the vehicle, but you can eventually identify the problem with certainty, instead of replacing parts blindly until the problem goes away.

If there isn't much difference between the hot terminal and the battery, try the ground side of the circuit. Probe between the ground terminal on the bulb and the battery ground post. There will probably be significant voltage there, so start narrowing that down. Test between the ground post of the bulb and the screw holding the ground wire to the body, then between the screw and the body, the body, and the body ground cable etc., until you get back to the battery. One of the ground connections will probably show significant voltage. Fix that connection, and then start over. In an old Jeep there are often several problem spots in a given circuit.

The basic rules to remember are:

1) The component that's supposed to be doing the work should show battery voltage, or very close to it.

2) All other components in the circuit should show very little or no voltage.

3) The voltage that will show up across any component is proportional to the amount of current flowing through it. If there is no current flowing in the circuit, the only reading you will get is at the point where the circuit is broken, and that will be battery voltage.

4) This won't work if there is more than one complete break in the circuit.

And for the sake of future discussions, what we're looking for here is called voltage drop. And if you're curious, the sum of all the voltage drops in a circuit, including across the component doing the work, will equal battery voltage.
 

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Discussion Starter · #12 ·
Re: yj question.. ((updated))

gee thanks... i'm going to go over there today.. thanks for all of the help guys
 

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Re: yj question.. ((updated))

This hasn't been mentioned yet, but disconnect the battery and put a 3/4" socket on the front of the engine and make sure it is rotating freely.
 

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Discussion Starter · #14 ·
Re: yj question.. ((updated))

ok i figured it out.... after me telling my bro-in-law to clean the terminals,(which he said he did)i re-cleaned the positive terminal. and what do you know, it started...... thanks for all of the troubleshooting help
 
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