Intermittent Discharge Warning, Filter, and Brake Warning lights on a BJ70- a few solutions

[Eurasiaoverland]

Very helpful and insightful tech in what you have shared here. Thank you

I am currently experiencing this on my Canadian spec (24V) '86 BJ70, but I have just modified my BJ70 by installing a different engine. My original 3B was a total loss so I have replaced it with a 15B-FT. Since the initial start-up of the 15B-FT, these three indicator lights have remained illuminated constantly.

I have confirmed that

A) my charge lamp relay is good (the relay checks out, plus I had a spare relay to use as an independent check)​

B) The 15B-FT alternator is good. Removed it and took it to an alternator rebuild shop. The shop confirmed that it charges (output was 28.1V) and the lamp off signal activates after steady charging is achieved. Also, the shop confirmed that the 15B-FT alternator has much higher capacity. [Max output was beyond 120 amps at 24V which was the equipment limit in the shop]​

Based on your experience, could you project other possible sources for these indicator lights to remain on?

Thanks

Did the BJ70 have an external voltage regulator? The 15B-FT will be internally regulated, so if your wiring is for an externally regulated alternator and you have not changed the wiring, that is likely to be the source of your problem.

 

[LDowney]

No. The alternator on a '86 Canadian spec BJ70 is internally regulated, so that would not be the cause.

How the original 3B alternator versus the 15B-FT alternator are regulated is the concern that I have. Specifically, differences in nominal amperage output between the alternators. They would both be regulated to the same voltage output (~28V), but it seems like the differences in amperage ratings between the alternators might yield differences that the relay could be responding to. For example could the charge lamp relay keep the lights on if the amperage is higher than design? Seems unlikely. I have never heard of an alternator failing in a runaway condition where it produces too much power. Checked other sources and this was incorrect.

 

[Eurasiaoverland]

I'm not familiar with the charge relay as my BJ60 does not have one.

If you're putting 120A through the vehicle wiring (e.g. charging a flat battery) it's not the alternator I would worry about. I take it you have done the 'Big 3' wiring upgrades to handle the 4x greater output of the alternator?

 

[LDowney]

...

If you're putting 120A through the vehicle wiring (e.g. charging a flat battery) it's not the alternator I would worry about. I take it you have done the 'Big 3' wiring upgrades to handle the 4x greater output of the alternator?

Concur. I made two changes (additions) for high amperage considerations. First, added fuses to protect original wiring from excess amperage. Second, added a dedicated high amperage wire* between the alternator output and the battery (24V post)

* 15B-FT came out of a Coaster bus. The wires at the alternator had been cut and left with the engine. I used the same gauge wire between the alternator-to-battery as the gauge of the wire remnant that was on the engine when I received it.

Thanks

 

[izula]

Hi @LDowney- I just noticed your post. It has been a few years since I tracked down these gremlins. I'll try to go over the factory schematics to see if there are any other things to try. I recall that the schematics helped a lot. The system is not that complicated, so it could very well be something really simple that you may have looked past. Reach out again if I don't post up in a day or two.