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Alternator problems?

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Alternator problems? 98 Lincoln Navigator 4x4 Battery light comes on upon starting and stays on. Sometimes the battery light doesn't ...

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Old 12-27-2003, 08:14 PM   #1 (permalink)
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Default Alternator problems?

Alternator problems?

98 Lincoln Navigator 4x4

Battery light comes on upon starting and stays on. Sometimes the battery light doesn't come on upon starting.

When the battery light stayed on, I checked the voltage to the battery with my voltmeter.

11.4 volts

When the battery light did not come on and remained off, I checked the voltage again.

13.4 volts

My guess is the alternator is getting ready to go. I believe the battery is the original battery that came with the vehicle, so my question is whether the battery could somehow be causing the battery light to come on or whether it's just the alternator or both.

My guess is the alternator due to the measured voltage I got when the light was both on and off.
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Old 01-02-2004, 04:10 PM   #2 (permalink)
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Okay, decided to change out the alternator which turned out to be the problem of my battery light coming on.

Here are some of the things I went through.

Okay, got the alternator replaced, but they leave out so many extra things that would be so helpful.

First off, this is a 5.4L engine with AC.

I simply removed the battery completely the night before since it was drained and needed to be recharged.

Next, I couldn't imagine how you would get the alternator out without the coolant hose and the air box hose into the throttle body in the way - so, those had to be removed too.

10mm socket wrench takes care of the plastic cover on the throttle body. The airbox hose to the throttle body looks much easier to remove than the coolant hose to the radiator and thermostat, so coolant hose stays and airbox hose goes. It takes awhile to loosen the hose from the throttle body, but it can be done.

Next is removing the three electrical connections to the alternator. Book just says to remove them. Two of the three connectors are snap-ons with tabs, so be careful when removing those. The third is bolted and you can't tell with the cap on. The cap is colored red on my truck, so hopefully it's the same on others.

Peel back the cap to reveal a bolt. Yup, it uses the same 10mm socket to undo the bolt. Be careful it doesn't fall down into the engine bay.

Now comes removing the belt. The book doesn't say anything about HOW to remove the belt using the belt tensioner. After some looking around, I found out that the belt tensioner needs a 1/2-inch driver and the belt tensioner needs to be pushed away (down) from the belt. Really tough to do on a 4x4 truck that sits high and I'm only 5'8".

I used a 1/2-inch driver and then took out my wheel lug bolt driver. Slipped the 19mm socket over the end of the 1/2-inch driver and the placed the wheel lug bolt driver onto the 19mm socket. Much greater leverage and it made pushing down the belt tensioner VERY EASY.

Once the belt tensioner is in the down position, it's easy enough to slip off the belt.

Alternator is held in place with three bolts. Yup, 10mm socket again. Loosen the bottom two first. It helps if you have a 2" extended, but becareful. I loosened it so much that the socket wrench came into contact with the fan belt and then I couldn't get the socket out. Had to screw the bolt back in to get the socket wrench out, then removed the extended to remove the bolts. The last bolt is on top. A 10" extender helps out to remove this one.

This alternator is heavy when you're leaning over the front of the truck (keep in mind that I've spent the last hour with my back hunched over, so it's not feeling well).

Massage that alternator out through the top.

Getting the new alternator back in is much easier and the install is just reversed of the removal procedure.

Now on to the rear differential speed sensor.......
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Old 10-21-2007, 02:23 PM   #3 (permalink)
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Just a helpful hint in case anybody encounters the same problem I had. After replacing my alternator with one from a chain parts house, my battery light would not go out. Went back and let them test it and the voltage output and diodes checked OK. Swapped them for another one. Same problem. Eventually tried 4 alternators from 2 different stores and always the same problem. Alternator charges fine but BATT light stays on. Decided to try a Motorcraft alternator and the BATT light finally went out. The parts stores were O'Reilly and Advance.
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Old 10-23-2007, 07:45 PM   #4 (permalink)
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Just an FYI if your ever not putting out ~14 volts your alternator is not functioning properly, or is possibly grounding and losing power somewhere in the vehicle. The truck can run without a battery once the alternator is turning, its puts out enough to run the truck.
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