Alternator / alternator light pbs

[lionel]

Hi Everybody,


I 'have a 88 Accord DX (carb) with 209kmi. Following an alt failure at 170kmi, I got a rebuild unit, on which I've already replaced once the regulator.

After replacing the alt, I ran into different problems:

1) alt light would go on while engine running depeding on whether condition (!), usually when cold outside. I also had at that time idling problems. I figured out the choke heater was shorted and replaced it. Idle pb is gone together with lamp glowing in the cold.

2) On very hot days, with A/C on, at about 4000 to 4500 RPM, lamp glows sometimes on and off. Can't always reproduce the problem. Could'nt figure out what it was. I thought it could be a ground trough ECU due to a bad TW sensor, I replaced the TW sensor, but the pb is still there....

3) I now have another pb: with ignition ON, and engine OFF, the light just goes on for 1 sec and then goes off, altough it should be ON. Alt seems to be charging fine (14.8V at the battery with high loads.) I checked the input to the (IG, L, and S), everything seems fine. Can't figure out what causes the lamp to goes off: it could be either the voltage regulator L connector going to 12V, or whatever is on this circuit (Choke, ECU/EFE heater) going to 12V.

Any ideas on pb 2) or 3)??

Thanks, thoses pbs are really driving me crazy!

Would you have any idea on pn 1) and 2)

[joebeets]

Engine off: My understanding of this circuit is, you’ve got the battery positive voltage on one side, the lamp in the middle, then EFE/choke heaters, and ground on the other side. Lamp glows.

Engine on: A new positive voltage, from the spinning alternator, appears between the lamp and EFE/choke. Lamp goes out.

But if the EFE/choke does not provide some electrical resistance, the new positive voltage is “grounded” and unable to oppose the original battery positive voltage. Lamp glows. You have experienced this.

Conversely, an *open* in both the choke and EFE, after 1 second, will turn out the light, with the engine off.

As for the flickering, suspect worn alternator brushes

[lionel]

Hello,

thanks for you reply. I agree with your understanding of how this light works. I performed new tests yesterday:

I was able to check the alternator (in fact the regulator) with the alt connector disconnected: with S ON and IG ON, the L connector (warning light) is 12V. Which explains why I get the light ON then OFF when I turn the IG ON: With IG ON, and the regulator not yet powered, the light is ON, Then within 1 sec or so, the regulator gets the power through the IG connector, and the L gets 12V, and the light gets off.

In other words, the regulator is not working properly, one of its transistor is not switching anymore.

The question now is what caused the regulor (1 year old, 15kmi) to fail. This one was intalled after I replaced the choke coil heater. I suspect I have a pb somewhere in the electrical circuit, but can't find where.

On the harness side of the L connector, the resistance with the ground is only about 40 ohms when the choke and ECU are disconnected. Seems weird to me.

I guess I can't do much than replacing the regulator and see what happens next...

[lionel]

hi,
late follow up on the problem...:
I made bibliographical search and found out the heat range of the Tempo regulator I had in the rebuilt unit was less than that of the original nippondenso regulator. The alt is located very close and beneath the engine so it can get very hot there in hot whether. With high electrical load (like A/C on, high RPM) the regulator will reach high temp and can fail if it goes over the heat range.
I put back the orig nippondenso regulator and it worked fine, no more engine light on !
Later the Tempo rectifier also failed, so I put in the rebuilt unit a used nippondesno one, working good so far.
Bottom line: stick with oem: Nippondenso /honda rebuilt is more expensive but to the orig specs. In some cases, it does make a difference.
Lionel