RTH New alternator, not charging (1 Viewer)

[musthave]

I just purchased a 2000 Land Cruiser from a forum member. Drove it 30 miles or so, battery light came on. Then no power.

I got a jump, and made it to advanced auto parts. Picked up a new alternator. Brought it to a mechanic that was open on Sunday.

New alternator in, isn't charging. Battery is new in 2022.

Thoughts?

 

[Eyedaho]

Check your cable connections from the alternator to the battery and battery to ground. Also check your alternator fuse in the fuse box in the engine bay.

 

[musthave]

Struggling here trying to help them. Do you know which fuse it is? Fuse box directly behind the battery.

 

[Eyedaho]

Struggling here trying to help them. Do you know which fuse it is? Fuse box directly behind the battery.

In the small fuse box on the battery cable.

 

[musthave]

In the small fuse box on the battery cable. View attachment 3375321

Awesome, thank you

 

[musthave]

Fuse is good. They're saying bad ecu. Signal not getting from ignition to ecu to terminal on alternator.

 

[cmw]

That sounds like a strange thing to suddenly happen, ECU I mean.

Many years ago I blasted the ECU in a BMW by jump-starting another vehicle ~ you might have two problems.

Is the previous owner unavailable, unable, or unwilling to help?

 

[musthave]

I paid for the new alternator and the seller brought it to me. I've messaged him with the news and haven't heard back.

 

[Eyedaho]

The connector on the alternator for that signal is notoriously brittle. I would check that for sure, I would pull and reseat the alternator fuses, and I would check the charging and ground cables. I sounds like they're actually checking electrical signals which is good, but the ECU diagnosis sounds odd, as stated above.

 

[Eyedaho]

The connector on the alternator for that signal is notoriously brittle. I would check that for sure, I would pull and reseat the alternator fuses, and I would check the charging and ground cables. I sounds like they're actually checking electrical signals which is good, but the ECU diagnosis sounds odd, as stated above.

By check the charging and ground cables, I mean I would disconnect and clean up the connection surfaces, even if you only have a pocket knife to scrape them clean.

 

[musthave]

Ground cable cleaned, they actually ran a new ground just to be certain. Fuse is good. The signal to the alternator is no bueno. No +12v.

 

[musthave]

Located an ECU 1100 shipped overnight to arrive on Tuesday if we don't make progress.

 

[Trunk Monkey]

Highly doubt it's the ECU, esp. if it was running before.

 

[musthave]

I have my doubts on the ECU as well. It is still good to have one on standby though. Looking through the sellers notes, I think the alternator issue is not new. He mentions all of the lights on the dash coming on, along with the battery light.

He stated that he solved it with a new battery. Which to a certain extent makes sense. The battery has 120 minute reserve you only drive it to the dentist and back you drive it 45 minutes total, then you put it on a battery tender when you get home. or so the story goes.

I believe I read notes about the battery light appearing more than once. So, I am now tending to think that this is an ongoing intermittent issue.

The fact that there is no +12 V to the connector on any one of the three wires when the vehicle is on is a little concerning though.

We will see where this goes.

 

[abuck99]

Try another alternator -

 

[musthave]

Late night fix. I believe we found the issue. The connector on the original alternator looked damaged. Corroded, residue, and possible signs of arcing. Inspected the female side on the harness. Apparently someone had noticed the broken connector and tab before and they fixed it with a wrapped piece of wire. The wrapped piece of wire was arcing, and causing in intermittent battery light on and alternator not charging. Found a section of harness in the junkyard from a Sequoia. Similar connector on the female side of the harness that plugs into the alternator. Replaced the connector and now it is good.

Hopefully this is the root cause.

Thanks for your help @Eyedaho

 

[Eyedaho]

Thanks for your help @Eyedaho

You're welcome. I'm glad you got it sorted!

 

[nissanh]

Glad you didn't replace the ECU: Please look for a different mechanic. These alternator are not run by ECU and have 3 wires to the built in regulator: Some newer cars has the voltage regulator inside the ECU, which is a poor design.