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Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 1808
Experience:  ASE Master Certification. GM World Class Certification
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Buick Lesabre With Symptoms of a Dead Battery.

Customer Question

The 1994 Buick Lesabre is showing symptoms of a dead battery. With a meter I checked the battery and its 12.8 volts. I checked continuity on the ground and it's 0 ohms. There is also 12.8 from the positive terminal to the block and alternator. The cable going from the battery to the power distribution under the hood is alternating between 0 and 9 vdc. Nothing is in between the positive terminal and the power distribution where the relays and main fuses are. No internal lights, no headlights but there is a constant clicking alternating from the left side of the dash to the right.
There are no blown fuses. From the battery to the main fuses under the hood the only voltage I'm getting is up to 9 vdc but its pulsing from zero to 9.
There is a clicking that alternates between the passenger and driver side under the dash. It can be heard under the hood but not as loud. Also, if I attempt to turn on the headlights or turn the dash dimmer up all the way there is a buzzing under the center of the dash. Also, Ive never pulled a dash before.
What more can I do?
Submitted: 11 months ago.
Category: Buick
Expert:  david craig replied 11 months ago.

Hi Im David, allow me a moment to check and get back to you. Thanks

Customer: replied 11 months ago.
Ready whenever you are. Like I said, there's nothing between the batter, which is at 12.8 and the power distribution center but the voltage from the positive lug on the distribution center and the negative terminal is pulsing. That tells me either there's a voltage regulator that resists ground that I've never heard of or there's some sort of regulating going on in the ECM that I have no experience with.
Expert:  david craig replied 11 months ago.
What happens when you try to start the vehicle?
Customer: replied 11 months ago.
It's as if the battery is dead. No lights, no clicking, nothing. The interior lights don't come on. The only thing I haven't tried is honking the horn.
Expert:  david craig replied 11 months ago.
What does the battery voltage drop to when you try to start it?
Customer: replied 11 months ago.
Nothing. Battery reads 12.8 consistently.
Expert:  david craig replied 11 months ago.
Check the main battery ground where it connects to the block. Make sure its clean and tight, make sure the starter cable is clean and tight. Make sure the battery terminals are clean and tight and any accessory grounds for the battery are clean and tight. Make sure the power distribution feed is tight and that the main 125amp fuse is ok.
Customer: replied 11 months ago.
Resistance from negative to block = 0 ohms. The starter cable wouldn't prevent the power seats or the interior lights from coming on and neither work. The battery cables are fine. I have 12.8 from the positive terminal to the block so I know I'm getting power through ground. Power distribution feed is tight and the voltage is pulsing between 0 and 9 vdc. I can't locate the main fuse but if it were blown would I have a glovebox light? I wouldn't think so.
Customer: replied 11 months ago.
is that a negative on a solution?
Expert:  david craig replied 11 months ago.

check these fuses and relay.......

Customer: replied 11 months ago.
Ok, I've checked every fuse I can find in the vehicle. I don't know how to check a relay. Can you at least tell me if there is some sort of a voltage regulator somewhere either external or in the ECM that might be breaking or resisting power to ground? The voltage from the single cable coming from the positive terminal to the power distribution box, which is not fused and is unobstructed by any type of terminal has a voltage that pulses from 0 to 9 vdc. How is this possible when the cable comes directly off of the batter to the power distribution box?
Expert:  Jake Cheek replied 11 months ago.

Hi I was reading your post and was wondering what fixed it? Was it an ignition switch?

Customer: replied 11 months ago.
It should've been obvious to me but for some reason I was doubting myself and wasting my time online looking for an answer. If you read my post you'll know that I was getting a pulsing voltage from the battery cable to the power distribution box which made no sense to me so I got online looking for a "professional" to help me with something difficult like the ECM or some other non factoring shit. What I failed to do was troubleshooting 101 and while I was checking continuity between the ground terminal and the block and checking voltage between the positive and the block it never occurred to me to check continuity between the positive and the power distribution box because it had voltage. It was the wrong voltage but since it was there I never checked continuity. When I did I actually got infinite resistance while still getting that pulsing voltage between the distribution box and the negative terminal so I took some jumper cables and jumped the existing cable and the car started right up. Looks like there's corrosion or a break in the cable and that was creating so much resistance that it was allowing my meter to pick up a little bit of magnetic resonance because it read infinite ohms and works fine when it's jumped.
Expert:  Jake Cheek replied 11 months ago.

Haha! Good for you, I'm glad you got it though. I probably would have sent you down that path initially. Most times its the simplest things! Thanks for taking the time to tell me. Maybe you should be an expert! But really good job. Electrical can be pretty tricky! Take care!