Xchekker94

I am the second owner of a 4th gen GLE with no modifications. My Dad was the original owner. The car has 78001 original miles. After many years with no major problems the CEL came on and it was throwing codes for the knock sensor and speed sensor. I replaced both, but after resetting the ECU, both codes re-appeared.


While troubleshooting the persistent CEL problem, the alternator burned up. Smoked. I could smell the burnt part. So, I replaced the alternator and purchased a new battery. Within 15 minutes of driving the car on a hot day under load with the stereo on and the AC set to Auto, the brand new alternator smoked. By that I mean, smoke was coming fron under the hood. I thought it was from the brand new brake pads and rotors I had also replaced so I didn't think it was the alternator, but it was.


After driving the car for almost fifty miles. the SRS light, and the Brake light came on, the dash led's began to dim and I heard a chattering relay on the passenger side of the car. I had experienced these symptoms the first time the alternator buned up and then because of that the battery had been practically drained. I managed to get home and when I tested the electrical system, I discovered that the alternator had burned up again. I didn't even put enough miles on the car to see if the engine codes were cleared.


What could possibly be causing a brand new alternator to go up in smoke like this? I've seen some posts regarding the brand of alternator or getting a Nissan part vs a remanufactured alternator, but have never seen ANY confirmation from anyone that just getting the expensive Nissan part is what solved the problem.


I don't want to keep putting alternators in the car. It's not that bad of a DIY job, but it's getting expensive to keep replacing the alternator and putting the time in fixing the car. If I can't solve these problems, I'm going to have to get rid of the car, and even though it looks great, I won't be able to get much $$ for it. Any help regarding the engine code problem and alternator problem would be appreciated.

Shift_A32B

iTrader: (14)

Are you leaking oil from your valve cover gaskets? I remember my dad's Mitsubishi Montero alternator kept going out because oil was falling on it from the valve covers.

njmaxseltd

iTrader: (19)

That's very strange to say the least. If something was drawing enough current to burn out an alternator, a fuse should blow. Look closely at the wiring from the alternator back. Make sure you don't have any pinch points and look for a hot spot. Measure the voltage at the battery, car running when you put another alternator in. Make sure it's not overcharging, you should see between 13.5 - 14.5 volts. If it's overcharging then the control voltage line is missing from the alternator causing it to charge full strength constantly. I think that voltage source actually comes from the gauge cluster. Has the cluster ever been removed? Many on here have noticed that with the gauge cluster out, the car doesn't charge. The two are tied together.

With only 78k on that car, you've got a gem!

Xchekker94

I'm going to pick up a new alternator this week and before I install it, I'm going over every inch of wiring that goes to and from the alternator and battery.

Here are a couple of pics. Some douche keyed the hood.

maxgtr2000

iTrader: (29)

Does look like quite a front valve cover leak you got there...

Xchekker94

Yah, I checked that out yesterday, but is definitely not the cause of the alternator problem. I've cleaned it up since I took the pic and haven't seen anything of significance leaking. So, even though it needs to be repaired, there isn't enough oil leaking out fast enough to smoke the alternator on a 2 mile trip to the gas station.

maxima2fst4u

I have an oil leak on mine that drips on mine hasent hurt it any been leaking on if for 3 years now...only thing i can think of is maybe ur tighting it to tight the belt and could be putting it in a bind...did u test the alternator after it smoked see if it was good or bad...

Xchekker94

Yes, I did check the alternator. Voltage across the depleted battery was 11.79 with the battery cables connected and the car not running. When I started the car it started the voltage started counting down: 11.54, 11.42, 11.29, 11.28... So, no charge was coming from the alternator. When the car started I should have seen charging voltage at least over 12.5 volts.

I'm just in from looking over the wiring harness and it is pretty corroded where the two grounding points are on the passenger side of the engine compartment. I hosed them down with PB and bolt for the one with the multiple wires brok off. Which makes sense because that one will be the most difficult to repair. The second grounding point bolt came out with no prollems.

The negative battery cable looks OK with only a little bit of corrosion at the battery cable connector, but the positive battery cable is a mess. The main cable has some corosion in the wiring at the crimp connector. And the two other cables that have click connectors are really corroded. The red plastic housing where the connectors slide in is so full of corrosion that the plastic is disfigured. So, I think I may have found the or at least *a* problem.

I hope it is *the* problem, because the only way to test this after I clean it all up is to install a new alternator and see if there is an over current situation.

I'll check back later with more description of what more I find and how I cleaned it up.