Dead short
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7th Gear
Joined: Jul 2013
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Dead short
I backed the C5 Z06 out of the garage. A rumblng noise from the engine department started and then the noise stopped. Everything then sounded normal. I shut the car off and checked for broken belt etc. I Then tried to start the car and everything was dead. I checked the battery and it was warm. I disconnected the battery and found a short between the positive and negative cables. I checked the cable to the starter by removing the wire from the starter motor and fuse block and did not find a problem. However when I reconnected the cable to the starter motor the short reappeared. Does this indicate a bad starter motor/coil or could it be something else? alternator? There is no short between the power block under the hood.
Thread Starter
7th Gear
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Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
When you say DEAD SHORT in reference to a 12 VDC 650 AMP battery, I immediately envision SMOKE, SPARKS, FIRE, Melted parts etc etc.....
What makes you think there is a short?
Please answer the following questions:
1. What is the battery voltage when read directly on the battery terminals? (battery disconnected)
2. When you connect the battery to the battery cables, do you get a small arc? (If you do, it normal)
Are you properly tightening the battery cables onto the battery terminals? The factory torque spec is 11 ft/lbs.
Thanks
BC
What makes you think there is a short?
Please answer the following questions:
1. What is the battery voltage when read directly on the battery terminals? (battery disconnected)
2. When you connect the battery to the battery cables, do you get a small arc? (If you do, it normal)
Are you properly tightening the battery cables onto the battery terminals? The factory torque spec is 11 ft/lbs.
Thanks
BC
Last edited by Bill Curlee; Dec 3, 2015 at 12:20 AM.
Race Director
Joined: Apr 2007
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From: South Western Ontario
How are you measuring this short?
You would be able to power-up the car and everything should work if you connect the battery with the starter disconnected. It just won't start so don't try cranking it. Just make sure that wire doesn't short out if you try this.
A "dead short" at the starter would have melted the battery cables and probably also destroyed the battery.
You would be able to power-up the car and everything should work if you connect the battery with the starter disconnected. It just won't start so don't try cranking it. Just make sure that wire doesn't short out if you try this.
A "dead short" at the starter would have melted the battery cables and probably also destroyed the battery.
Last edited by lionelhutz; Dec 3, 2015 at 12:54 PM.
Thread Starter
7th Gear
Joined: Jul 2013
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How are you measuring this short?
You would be able to power-up the car and everything should work if you connect the battery with the starter disconnected. It just won't start so don't try cranking it. Just make sure that wire doesn't short out if you try this.
A "dead short" at the starter would have melted the battery cables and probably also destroyed the battery.
You would be able to power-up the car and everything should work if you connect the battery with the starter disconnected. It just won't start so don't try cranking it. Just make sure that wire doesn't short out if you try this.
A "dead short" at the starter would have melted the battery cables and probably also destroyed the battery.
The cable to the starter was isolated and was found to be good.
The problem seems to be the circuit from the starter motor/ coil and the alternator inclusive. I need to confirm this. If the alternator is bad, should I be able to see this if I check the resistance between ground and the power terminal on the alternator?
Could there be a short that is coming back through the alternator from an accessory or other item?
Also, in case I need to change the starter motor, is there enough play in the exhaust system to just disconnect the exhaust at the manifold or will I need to disconnect at the rear as well?
This is a stock 2001 Z06.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The large red wire on the back of the alternator (BATT TERMINAL can be removed and isolated. That wire goes DIRECTLY to the starter solenoid (it has an inline fuse)
So, you can read that wire to engine & chassis ground. Should be infinite resistance. You can also read the BATT terminal to alternator case. It should be infinite resistance.
There are THREE red wires on the main terminal on the solenoid. The LARGE one goes directly to the battery. The next largest one goes to the alternator and the small red wire goes to pin D on the small plug on top of the alternator. You can see the fused link on the wires.
BC
So, you can read that wire to engine & chassis ground. Should be infinite resistance. You can also read the BATT terminal to alternator case. It should be infinite resistance.
There are THREE red wires on the main terminal on the solenoid. The LARGE one goes directly to the battery. The next largest one goes to the alternator and the small red wire goes to pin D on the small plug on top of the alternator. You can see the fused link on the wires.
BC
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From: South Western Ontario
I would be very doubtful of the alternator failing and causing a battery melt-down. There are fusible links on the wires which would burn-open if it failed and started drawing high currents.
There are no accessories in that circuit. Just the cable from the battery to the solenoid and 2 wires from the solenoid to the alternator.
There should have been something smoking hot if it was drawing enough current to destroy the battery.
There are no accessories in that circuit. Just the cable from the battery to the solenoid and 2 wires from the solenoid to the alternator.
There should have been something smoking hot if it was drawing enough current to destroy the battery.
Thread Starter
7th Gear
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Thanks to all who responded. The problem was a short in the starter motor. I isolated the short to the starter, removed the starter and took the starter to Advance Auto to check. Advance performed the check at no cost and verified the problem. I installed the new starter and the problem is corrected,