03 LX - no power from alternator, could it be something other than an alternator? (1 Viewer)

[nckwltn]

**updated

See this post from this thread for what I'm confident the issue is. 03 LX - no power from alternator, could it be something other than an alternator?





started my truck up this morning and noticed the alternator wasn't putting out any voltage. It's a new denso remanufactured from Lexus installed 3 weeks ago. Verified that it was the alternator by pulling the negative terminal while the vehicle is running and the car immediately stopped. Hold the negative terminal and left it off for a few minutes put it back on and the alternator begin to charge again.

I haven't had a chance to search through the forum, so apologies if this is a heavily discussed topic. I am traveling through Arizona with limited internet connectivity.

Anyone have thoughts on where I should or could begin troubleshooting?

Thanks!

 

[nckwltn]

I should add that I had a similar issue with the previous alternator that led me to believe the alternator was bad. Car was running not putting out enough voltage oh, I had an electrical smell coming from the engine bay testing indicated at the alternator was problematic so that's when I replace it with the remanufactured from Lexus

 

[nckwltn]

Yesterday after pulling the negative cable on the battery for a few mins, the alternator worked fine all day long. Several starts and stops and 90+ degree day in eastern AZ.

Now again this am, it isn't putting out any voltage.

Trying the negative terminal trick to see if that will reset anything.

Does this intermittent charging issue point to anything other than an alternator?

 

[nckwltn]

For the 2nd day in a row, pulling the negative cable for a few mins seems to have restored functionality to the alternator.

Is there something I might be able to look at via tech stream that could give me some code that wouldn't show up as a check engine light?

 

[nckwltn]

The saga continues.

I was able to replace the alternator with a Denso part from Lexus. Seemed to work fine for one day, but the 2nd day (today) no voltage from the alternator first thing in the morning.

to recap

3 weeks ago I had a low voltage from alternator on a 196k '03 LX. There was a bearing type sound coming from engine bay, it seemed likely the alternator needed to be replaced. I pulled what I think was the original alternator and I could hear some bearing noise when turning by hand.

I replaced the alternator with a reman Denso from Lexus.

2 weeks later I was getting the same issue with no power coming from the alternator. The car runs just fine off the battery, but I can pull the negative terminal on the battery and the car dies right away.

I was able to find another reman Denso at a dealer and swapped out alternators. The new alternator worked fine for 1 day, but on the 2nd day it showed the same problem as the last reman.

It seems unlikely that the alternator is my issue.


my issue is that when I start the car first thing in the morning the alternator doesn't put out any voltage. I've been able to disconnect the negative terminal on the battery for 5-10 min and upon reconnecting the battery the alternator will start to put out voltage.

After the alternator starts putting out voltage it works for the remainder of the day. We are on a road trip and start/stop the car several times throughout the day. Sometimes for more than an hour or two.

it's every morning that there is an issue.

I have one of the 27F AGM x2 batteries that is less than 2 months old. The only aux electrical connections to the battery over night is a dometic cfx3 95 dz.

one thing I thought was interesting was that both reman denso alternators have some green colored corrosion on the same area of the diodes. One alternator came from Lexus in CA, the other came from Lexus in CO. I suppose I could have ended up with 2 bad alternators, but that seems pretty unlikley.

Here are pictures of the corrosion from each alternator. The 2nd had a little less corrosion than the 2nd, but they both had them in the exact same place.

This thread looks like it might be somewhat of a similar issue: Landcruiser V8 100 Series not Charging


Anyone have suggestions on something I should be looking at to track down the issue?

 

[nckwltn]

After a little more diagnosis I found that the battery light in the instrument cluster doesn't come on at all. Not when I put the key in the ignition, but before the car starts up.

I pulled the cluster, but it looks like the bulb for the battery light is behind the circuit board, that requires the gauge needles to be removed to access, and I didn't want to break the analog gauges trying to get them off.

(wondering if I can test the light with tech stream)


Also, I do get battery voltage at the 7.5 amp alt-s fuse, but I only get .4-.5 volts at the FR-IG fuse.

 

[ramangain]

After a little more diagnosis I found that the battery light in the instrument cluster doesn't come on at all. Not when I put the key in the ignition, but before the car starts up.

I pulled the cluster, but it looks like the bulb for the battery light is behind the circuit board, that requires the gauge needles to be removed to access, and I didn't want to break the analog gauges trying to get them off.

(wondering if I can test the light with tech stream)


Also, I do get battery voltage at the 7.5 amp alt-s fuse, but I only get .4-.5 volts at the FR-IG fuse.

You don't need to remove the front gauges to get to the bulbs. I don't recommend fiddling with the gauges; I've made that mistake and it took tons more fiddling to get the tach needle to read correctly and smoothly after I touched it ONCE.

Have you dealt with ribbon connectors and clips before? If not, watch a YouTube video first. Everything unplugs or unscrews so the circuit board lifts out of the way. Might was well replace all the bulbs with fresh ones while you are in there too.

GL

 

[ramangain]

Also, can you get your hands on a non-AGM battery and try it, especially overnight?

 

[nckwltn]

I think I've pinpointed my issue.

The FR-IG fuse wasn't getting battery voltage with the key on, and my battery light wasn't on. FR-IG should get power from IG1-NO.1 relay.

I believe the IG1 NO.1 relay is located under the main fuse block in the engine bay. I was trying to get the top of the fuse block removed so I could check the relay. I couldn't get fuse block opened up, so I though I would just tap the box with the car running.

I went to start the car and the battery light came on. So the bulb isn't out, and now with the battery light coming on, I'm getting alternator voltage.

All of this is pointing me to the IG1 NO.1 relay.... now I just have to figure out how to access the relay

 

[nckwltn]

it may not be possible to just replace the relay

2005 LX470 Main Junction Block Replacement

So I finally bit the bullet and replaced the main engine room junction block to cure the intermittent AC operation. For this year, the AC relay cannot be replaced separately as it is built into the junction block itself. The replacement part number is Toyota 82720-60081 with a list price of...

forum.ih8mud.com

 

[nckwltn]

I have all but confirmed that my issue is a relay inside the engine compartment relay/fuse/junction box.

Basically it appears that the relay IG1-NO.1 tells the alternator that the ignition is on, and that the alternator should be putting out voltage. This relay also is responsible for illuminating the battery light in the gauge cluster.

If you pull the alt-s fuse, the battery light will come on, but if you pull the IG-FR fuse the battery light will not illuminate and the alternator will cease putting out voltage.

I believe that a trail fix could work by running a fused wire from the battery to the side of the IG-FR fuse that would be receiving battery voltage through the IG1-NO.1 relay. This will basically bypass the relay and tell the alternator that it should be putting out voltage. This trail fix would need to be removed when the car ignition is off. This would best mimic the ignition itself.

Sadly, the relays on the main junction block are going to be difficult or expensive to replace. (see my previous post)