02 Won't Start

All, I did a voltage check across the two connections on the strarter solenoid and have 12.5vdc with the key off. By looking in the manual, that should not have voltage until the key is turned to the start position. Is that right? I thought the negative side got it's ground through the engine starter relay in the power distribution center. I failed to clarify in my earlier post that I get no action from the starter motor. Thanks D

I would rather thirteen and a half. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com

Great thought Bill. Thanks, I'll try that in the am. D

Who gives a shit how your wife's was put on, he didn't ask a fucken thing about your family ignoramus.

I need to mention too that the lights do not dim in the least when I turn the key to start. That would indicate an open to me, but then again, here I am asking. Thanks. D

I would give the starter a good thump with a rubber mallet or a chunk of

2x4 or a tire iron or a brick or whatever I had and then try it.

If it then starts, the starter is in need of new brushes.

If there is a bad connection, the bad place 'usually' will get hot after a few tries at starting from the arcing. You can 'carefully' feel the cable ends for heat to check this.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > I need to mention too that the lights do not dim in the least when I turn

Thanks Mike. I just got back in from the "thump" test. No Joy. Measuring across the battery terminals, I got 12.54vdc. I turned the key to start with the meter connected, and it dropped to 11.45vdc, slowly returning to about 12.15vdc. I don't know if that's severe, but I have the charger on the disconnected battery now to see what happens. Will check the solenoid connections while it's charging and let you know what happens in about an hour. Oh, I find no hot spots in the circuit. Thanks D

That 'should' be an OK battery with a starter issue from those readings.

Mike

D wrote:

There should be a +12 feed right from the battery to the solenoid whether or not the key is on.

This is the huge wire that carries way too much current to be switched by the key, the starter relay etc. The solenoid is what switches this high current 12 volts to the starter when you turn the key to start...it is just a very large high current relay.

Your ignition switch has two circuits that control the starter.

The ground side of the ignition switch signal is routed through the park/neutral switch on an automatic transmission. If that circuit is open your starter relay will not close.

The hot side of the ignition switch signal heads for the small starter relay. The starter relay will send +12 to the starter solenoid when you turn the switch to start...if none of the interlocks prevent this.

Your solenoid always has +12 on it while the battery is connected. The small +12 wire from the starter relay is used to switch the solenoid so the high current 12 v goes to the starter. If you have a big sears or similar screwdriver, you can turn on your solenoid by jumpering the big red wire to the output to the starter. If that turns over the engine, then one of the interlocks, the ignition switch, the start relay etc. is the culprit. If you cannot turn the engine over with a direct jump across the solenoid, you have a bad cable, which includes the ground side of your battery.

Common mistake in diagnosing is to check voltages from the connector at the battery... need to use the posts themselves.

Your problem sounds somewhat like an interlock, which can be a real bear to isolate unless you have friends and a long diagnostic jumper wire or take a spare starter relay apart and jump across it.

However, check the big cabling first.

With someone helping by turning the starter on, measure the voltages to ground and to the starter solenoid large wire.

From the ground post on the battery to the engine and then again to the body, you should see well under 0.2 volts with the switch to start.

Then check from the positive post to the solenoid, again with switch to start, you should see well under 0.2 volts.

Any point where you see more than 0.1 volt is a big red flag of a bad cable or connection.

D proclaimed:

Do you think he would get a full volt drop at the battery on 'start' without the starter pulling power? He does say he hears a click, but that might not be the starter solenoid...

Good point about the interlocks though, trying to start it in neutral would be worth a try.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

You guys are all great! I printed this out for future use Lon. Very good info. Problem solved, for now anyway. I put a deep charge on the battery and got a start. I redid every connection on the solenoid and prepped the cables for a new battery. Charging circuit seems to check out okay. With a 'guarded' thank you, I'll see how it goes. I might stop into Autozone just to confirm my readings that the charging system is working up to par. Thank you all again for your prompt and very informative help. D

Mike Romain proclaimed:

Yeah, that volt drop is odd. However, he also said the lights don't dim, which is hard to reconcile with the full volt of drop.

If the click is loud, suspect would be simple bad battery that won't pass a load test, cables, or possibly the ground on the '02 carries on the grand old traditions.

If the click is quieter, could be the start relay... in which case the interlocks are off the suspect list.

The switch could be bad.

I'd be more likely to use a Sears screwdriver at the solenoid.

You might want to price a factory service manual.

Charge it up good, then give it a load test. Measure across the posts. Turn on the lights for 10 minutes. Measure again.

Pretty good at finding a surface charge where the voltage looks good until you load it.

If this is the original battery, replace it. Sears sells nice SUV Die Hards and Optimas...both of which work pretty good.

If there is even the tiniest bit of crud at your cable connects, buy a cheap terminal cleaner brush.

D proclaimed: