Question about 1994 Buick LeSabre
I replaced the alternator on my car because the bearings were bad. After doing this it will not charge the battery. I have had the new alternator tested and it checked fine as well as the battery. the output wire looks good and was replaced last year.
Before, you buy a new Alternator or Battery... Check the Battery with a DC-Volt meter. It should read 12.5 volts or more with the key off. If the Battery reads less then 12.5 volts, have it charged free at Autozone or O'Reiley's auto. If the voltage is 12.5 volts or more, start your engine. With the engine running check the battery voltage again. It should read 13.5 to 15.5 volts. IF YES, Your charging system is work fine.
**IF NOT, and your Battery voltage 12.5 or less, You DO have a charging problem. It must be 13.5 to 15.5 volts!!! 1 - The first thing you want to check is the Battery cables and Battery post contacts. Remove the Negative cables FIRST!!!! Then the Positive, Clean the battery posts and cables with a wire brush!!! There are (3) Large Black cables on the Positive post of the battery, one goes to the starter, one goes to the relays & fues on the fire wall, and one goes to the back of the Alternator Battery output terminal.
Remove and clean the cable, nut & terminal of the Alternator with a wire brush. Then, reconect it tight to the Alternator output terminal. Now, there is (1) Large Black cable & (2) small wires on the Negative post of the Battery. The Large one goes to the Engine Block Ground. The small ones go to the front fender screw on the passenger side car body. Clean them with a wire brush. The most IMPORTANT GROUND is the Large Black cable from the Negative of the Battery going to the ENGINE BLOCK!!! To Remove & wire brush them clean, fallow the Large Black cable going to the Engine Block under the side coil assembly. Remove (3) NUTS & a triangle metal shild. clean all (3) wires & the Bolt & NUTS. Re-assemble very tight!!!
When completed, Reconect the Positive Battery cables firt! Then, the Negative Cables. Make sure they are all making good contact and are nice & tight. Now, check your battery voltage again with the car off! It should be 12.5 volts or more. Re-start the car, Check the battery voltage for 13.5 to 15.5 volts. IF - YES....IT'S FIXED! IF - NOT.... Turn the car OFF & look for a small black conector that plugs into the side or under the Alternator. It will have only (1) small RED wire going to it.
Very carefully, stick a straight-pin in the red wire & let the pin come out the other side. Don't let it touch any metal !
Start the car & let it run. Now put the (black) lead of your DC-Volt-Meter on the Negative of the Battery. Then, put the ((red) lead of your meter on the straight pin. It MUST have 8.0 to 12.0 DC-volts there !
IF - YES... The regulator inside the Alternator in BAD. (REPLACE) the Alternator. IF - THERE IS NO VOLTAGE there... Then, the red wire is bad... or the (P C M section) inside the ENGINE CONTROL MODULE is BAD!
The Alternator is about $100.00, The red wire is about $2.00, But the ENGINE CONTROL MODULE is about $400.00 plus from a dealer. Only, about $170.00 from autozone and about $125.00 from a wrecking yard.
**** NOTE **** If your Engine Control Module is bad, Look for my INFORMATION on FIX-YA, "HOW TO REPLACE THE ECM on a 94 BUICK" Thanks and GOOD LUCK !!!
Posted on Nov 01, 2012
If the harness is good then see if you have a battery light on in the dash when the key is turned (eng off) on, if this light is not on the alt will not charge, the field has no excitation to it.
Posted on Nov 14, 2008
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Posted on Jan 02, 2017
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