MoTeC Global Forum

At the moment I have the alternator lamp output from the alternator to the Digital input Pin of PDM15 (DI2) I've set up the CAN output message to message 1, offset 5.

In the dash manager there isn't really an option for the lamp so am I on the right track in just using the "user 1" channel and set the alarm to be true for when channel "user 1" is active.

I've have to work out the polarity once the wiring is complete. Or am i misunderstanding how alternator lamp work?

The engine i'm working on is F20c engine with m130, pdm15 and C127. using standard honda s2000 alternator. the alternator has 4 pins, but i'm only using 2.

It may not work how you are thinking if it is a typical alternator lamp (Depending on how you have wired it up, is the original lamp still in the circuit?)

Typical older lamps get 12V from the ignition circuit on one side and a ground via the alternator to turn on the lamp, when the alternator starts working that ground becomes 12V (Approximations here) and as it has 12V on both sides, the lamp goes out. I am not familiar with that particular alternator. If the original light is still wired in and working then it would presumably work OK into the PDM if it works as i described above.

I assume you mean pulling the CAN message into the dash under user 1? You would be better off with "User alarm 1" as that is a true/false channel and you could then use it more simply to drive an alarm.

If the alternator is working normally without the connection to the PDM it might be easier to simply set up an alarm in the dash when battery volts drop below say 12.5V with a second condition of engine RPM being over 1000. That has the feature of bringing up an alarm on the dash even if the alternator light would not be on (Many don't bring on a light for failures such as worn out brushes as the ground to bring on the light includes the brushes in the circuit)

Depending on how your alternator actually works you will most probably need a pull up resistor to 12V if you have removed the lamp.

One thing to remember is you can rename any of the channels in the Dash to whatever you want. So basically select a channel that has the correct units and resolution (Such as the "User Alarm 1" the_bluester suggested) then go to Tools>Edit channels and change the name to something more suitable.

the_bluester wrote:It may not work how you are thinking if it is a typical alternator lamp (Depending on how you have wired it up, is the original lamp still in the circuit?)

Typical older lamps get 12V from the ignition circuit on one side and a ground via the alternator to turn on the lamp, when the alternator starts working that ground becomes 12V (Approximations here) and as it has 12V on both sides, the lamp goes out. I am not familiar with that particular alternator. If the original light is still wired in and working then it would presumably work OK into the PDM if it works as i described above.

I assume you mean pulling the CAN message into the dash under user 1? You would be better off with "User alarm 1" as that is a true/false channel and you could then use it more simply to drive an alarm.

If the alternator is working normally without the connection to the PDM it might be easier to simply set up an alarm in the dash when battery volts drop below say 12.5V with a second condition of engine RPM being over 1000. That has the feature of bringing up an alarm on the dash even if the alternator light would not be on (Many don't bring on a light for failures such as worn out brushes as the ground to bring on the light includes the brushes in the circuit)

The Alternator has 4 pins on the plug, plus 1 m6 stud for the battery/starter. Previously the car was wired with just 1 wire which i assumed was IG. But the alternator keeps on dying, I've been through 3 alternators in 2 races. The original instrument cluster is gone.

From a bit of googling it looks like the S2000 alternator might be controlled by the ECU? I have not yet found out for sure but maybe it is one of the ones controlled by a PWM signal out of the ECU that directly controls alt output to give the desired voltage.

What sort of voltage are you seeing when the car is at decent RPM?

When the alternator was working I was seeing, 13.7 to 14.1 V,

The M1 ECUS GPR package has some sort of alternator control. I'll look in to that. I've got all the output to use since everything else is CAN controlled.

I've set up the Alarm for Low batt voltage in the dash manager

Hi everyone,

I have a problem with the Alternator Lamp on C127 too.

How to configure Alternator Lamp on C127 with M800 PnP ecu for Evo 9 ?
Alternator will not working if not using Alternator Lamp.

Every advice will be highly appreciate.

On the Plug-in, alternator is controlled by Aux 4.
What do you want to do with the C127?
Do you just need a warning when voltage is low?

Hi

I don't want to use the standard dash, just only using C127 to replace it.

You have not answered my question.