About the Blinking Lights on the N1509 Regulator

[Lugnuts]

I was once told that when you have a different subject to bring up you start a new post, so I am but it is still in regard to Alternators. On a recent post I was dealing with a N1506 Alternator and found that the alternator itself was bad. I went to Forestry Division who is handling parting out some of the trucks and I obtained a N1509 Alternator, unknown condition. I commenced to bolt in and all wiring is the same, cleaned connections, and started. I immediately saw that I had no blinking lights. I checked voltage at battery and alternator and found acceptable charge rates, a touch high but acceptable/ 28.6vdc and 14.4vdc/ I obtained the Niehoff Manual and it stated that if lights were not on that regulator was not on, to check pin e for voltage and I haven't got back down there to do that. My question is why do I have acceptable voltages if the regulator is not suppose to be on and can I use the truck this way. I am not asking permission but merely asking for the experience of those who may have had this happen to them.
So I painted a target on me, fire away guys., and thank you

 

[GeneralDisorder]

It's not impossible for the LED's in the regulator to have failed or part of the circuit that drives them - do you have another regulator from your old unit to try? Those voltages are good - you will have about a 0.70v drop across the polarity protection device so that's exactly what you want to see from the alternator.

 

[Suprman]

If you dont have 24v at the front regulator terminal the alt will just spin and not charge. Jump 24v to the front regulator terminal see if the leds light up and it starts to charge.

 

[Lugnuts]

It's not impossible for the LED's in the regulator to have failed or part of the circuit that drives them - do you have another regulator from your old unit to try? Those voltages are good - you will have about a 0.70v drop across the polarity protection device so that's exactly what you want to see from the alternator.

The other Regulator has no Lights. Thank you for your response and I will do the flow chart on Saturday and post the results. I know for sure that when you start the truck and watch the voltage gauge you can see the oil pressure happen and then the alternator fire up.

 

[Ronmar]

What General Disorder said. It could be that the monitor circuit has failed. Since it is putting out power, I suspect you will find 24V on the forward screw terminal(E/EXC/ENG) when the engine is running.

It is obviously making power if you are seeing 14 and 28V. The voltages that Neihoff specced for these(14.1/28.2) has always struck me as a little low. Automotive standard for a alt feeding a lead acid is 14.5+/- 0.5V, so yours are not a touch high, everyone elses are a touch low…

Glad you got it working.

 

[INFChief]

FYI: Back in my day output of 28.6 is fine. Anything up to 29 was ‘OK’. The gauge / indicates on the dash is pretty good but they aren’t super accurate and as far as I know they aren’t calibrated.

 

[GeneralDisorder]

What General Disorder said. It could be that the monitor circuit has failed. Since it is putting out power, I suspect you will find 24V on the forward screw terminal(E/EXC/ENG) when the engine is running.

It is obviously making power if you are seeing 14 and 28V. The voltages that Neihoff specced for these(14.1/28.2) has always struck me as a little low. Automotive standard for a alt feeding a lead acid is 14.5+/- 0.5V, so yours are not a touch high, everyone elses are a touch low…

Glad you got it working.

And after you run those voltages through the PPD/LBCD the diodes drop the voltage another 0.7v so what you see at the PDP is about 27.5v and 13.4v. Which is really fine as everything computer-wise has to run on 10v or even lower during cranking. The batteries see 28 and 14 not being on the load side of the LBCD.