ECUmaster PMU16 noob question

Hi there,

I am currently in the process of following the PMU course and while i was filling in your example sheet it looks like i am running low on outputs.

I'm probably overthinking this, but is it possible to combine different components on the same output without having them work at the same time? I'm having a little brainfart on this.

I was thinking about for example putting the headlight low and high beams on the same output while still switching them independently, if possible. So putting them both on the same output while using different CAN keyboard switches to put them active.

There's a copy of my worksheet added to see what i mean.

Also, when i was looking at my mapfile from the EMU Black i noticed there are some outputs coming from that aswell, mainly engine stuff. Does this mean they will get powered automatically if i hook up power to the ECU? If so, that means i can scrap some stuff that i've assigned to my PMU.

Hey Melvin!

"I'm probably overthinking this, but is it possible to combine different components on the same output without having them work at the same time? I'm having a little brainfart on this."

So, yes, you can do that, but you would need another circuit to make them switch from one to another. A mechanical relay controled with a switch with one circuit connected to the 87a and the other to the 87 could do that for your low and high headlights (only one of them would be ON at the same time). In my opinion, I would avoid that if I could. One of the problem is that the Highbeam could need more current than the Lowbeam, so your current limit could not be the same for both light set. Instead, I try to group circuit that will be powered at the same time as much as possible to save the number of output as much as possible. For example, you could power the ECU, Dash Logger, Keypad, Steering Wheel from the same output. VVT Solenoid, Boost Solenoid, Lambda Sensor, Alternator Field could be on the same one as well, as it is unlikely that these circuits will be powered with the engine off.

A good example of grouping circuits that are not powered at the same time would be your rear light (parking), license plate light, reverse light, brake light. They could be on the same output as the reverse and brake light are already controled via additional switches in the transmission and on the brake pedal assembly. The PDM would supply current to the license and parking lights (which would be on at this point) and to the trans and brake switch, and the reverse and brake light which would only come ON when the switches are actuated.

"Also, when i was looking at my mapfile from the EMU Black i noticed there are some outputs coming from that aswell, mainly engine stuff. Does this mean they will get powered automatically if i hook up power to the ECU?"

No, first of all the Aux output of the ECU Master are switched to ground, or lowside output as some of the manufacturer called them. They will provide a ground when certain conditions set in the ECU are met. For example, the fuel pump would be powered for 2 seconds to prime the system, then stop until the engine is cranked. Or the boost solenoid output would provide duty cycle as set in the boost tables. Having a PDM, you probably won't be using the ECU to control the fuel pump and electric fans, which would be controled directly from the PDM. All the information that the PDM need to control there will be on the CAN Bus, so it will simplify the wiring.

Hope it helps,

Frank

Hi Frank,

Thank's for your detailed reply!

Ah ok so it is possible to do that, but i would like to not use any relays to be honest, to keep everything as clean, tidy and simple as possible. I was hoping to be able to control everything from the ECUmaster can keyboard.

I will have a look to see if i can group some more stuff on the same output. I was thinking about giving the ECU its own dedicated output as described in the course, so nothing else on that output can interfere with the ECU's power supply should things go wrong someday. I can drive the car without the dash logger for example, but not if the ECU wouldn't work anymore either.

Another thing is that for the car still being road legal, i would like to keep the low beams on aswell when i put the high beams on. On my current application with xenon headlights, the MOT rules even say that they HAVE to stay on while i switch to high's, reason being the xenon bulbs have a start-up time.

I will be replacing those with LED projectors but for the sake of having as much light as possible on high's, i would like them to stay on.

''VVT Solenoid, Boost Solenoid, Lambda Sensor, Alternator Field could be on the same one as well, as it is unlikely that these circuits will be powered with the engine off.''

I've grouped those together now, but what about ignition coils and injectors? Could these be grouped aswell? Or is this not to be advised?

As you can see in picture below, i've added quite some stuff to output O9. This output is rated for 15A if i'm correct. If i add all the estimated steady currents up i'm at 11.7A. But the in-rush currents would be able to exceed that 15A limit. Is this going to be a problem, or is it possible to go over the 15A limit for a moment of time with the in-rush current?

Designing a harness is always a game of compromise and risk management! So I understand you want to isolate your ECU from the rest of the circuit so you could drive the car in case something goes wrong. If you can afford using a dedicated output for it, that could be a good idea. But you could also physically disconnect the faulty components in order to drive your car back to the shop.

With the need to have your low and high beam light ON at the same time, it would be easier to do this with the PMU. But it will takes 2 outputs.

For your other questions :

Yes, you can go over the limit for the in-rush current. The rating of the outputs of the PMU16 is for continuous operation. If you take a look at the PMU manual, they configure the 25A Outputs with a in-rush of 30A for 1s as an example.

Yes, you can group injectors and ignition coils power together.

I group ECU/Injectors/Solenoids/Lambda/Dash Logger together. There is no reason for them to be controlled separately. I leave the coils separate so I can stop the engine. I would think you need the keypad to be powered all the time (so it can control the PMU), but perhaps you have a separate master switch.

Use separate circuits when it makes sense for the PMU to control them based on CAN messages from ECU, Keypad, Steering Wheel Buttons. So it might make more sense to have an output for each horn, fan, washer pump.

For a street car with all those devices I find that you might need a 32 output PMU (or two PMU16s).

I know HPA courses separate ignition (not ignition coils, but more like the OEMs "accessory" key position in a car) and enable circuits. And to me it makes sense that you could want to power the ECU and Dashlogger without powering the rest of the engine circuits in case you want to work in the tune or dowload log without having the Lambda sensor heating with the engine off.

I agree with David that it's gonna be hard to achieve with only 16 outputs for a street car. I designed a harness for a Rally car and we ended up using a Bussman fuse and relay box to add up a couple of circuits that we didn't really want to log or control from CAN messaging. They are neat unit and you could use low side output to activate the relays.

I group ECU/Injectors/Solenoids/Lambda/Dash Logger together. There is no reason for them to be controlled separately. I leave the coils separate so I can stop the engine.

I will also be installing a battery isolator to turn the engine off in case of an emergency, so that should be fine to wire coils and injectors together i think

I would think you need the keypad to be powered all the time (so it can control the PMU), but perhaps you have a separate master switch.

I am planning on using the original key barrel as a ''master switch'' to power the PMU on, also to have some sort of anti theft system with my key still in place

Use separate circuits when it makes sense for the PMU to control them based on CAN messages from ECU, Keypad, Steering Wheel Buttons. So it might make more sense to have an output for each horn, fan, washer pump.

For a street car with all those devices I find that you might need a 32 output PMU (or two PMU16s).

Maybe it would have been better to wait until March for the new Ecumaster PMU with 24 outputs to come out, but i am not sure if i can still return my PMU16 to where i bought it from

But maybe it will be possible to pull it off with the PMU16 as i have it right now:

My friend reminded me i need to power my ABS unit aswell, so i switched the park/rear lights to output 10 and put the ABS unit to output 3. But i have also contacted the shop i bought the PMU from if it's able to return it and wait for the new PMU24 because i believe that would make it a lot easier to get everything working withouth cramping lots of stuff together on the same output.