LS1 Electric Vacuum pump control - 5v input 12v or Gnd Output capabilities?

[evilstuie]

Hi All,

I've got an issue with my brakes that requires some auxiliary vacuum which I've decided to use a UP28 electric pump. I also got the Bosch# 20876799 vacuum switch to turn it on and off, but I thought this would be a simple, 12v output to a relay to switch on and off when the vacuum pressure was out of range.

Turns out it is controlled by the PCM on cars like the VF commodore and E39a PCMs using a 5v reference, low reference and signal wire.
Assuming the switch output is 0-5v, is there any table I could utilise in the HPT SD OS that could send a 12v or ground signal to a relay to kick the pump on and then off when it reaches a certain voltage?

I'm already using EGR for my wideband, but was thinking possible the EVAP controls or something similar?

I'm just looking to find if there's a way I can do it without going and buying a $100 12v vacuum pressure switch.

[kingtal0n]

arduino microcontroller, 2n2222 transistor darlington pair, and 1-bar map sensor ?

[evilstuie]

arduino microcontroller, 2n2222 transistor darlington pair, and 1-bar map sensor ?

Perfect!

... I don't suppose you have a circuit diagram or link to someone who's done it?

I was thinking that might be the answer and I haven't had the time to start learning Arduino, but this looks like a good place to start.
Even if I end up spending the same amount on a pressure switch it'd still be worth it.

I'm also working on a completely custom dash with carPC and android so Arduino may come in handy if I need to tie anything else in to those such as automation and relay boards etc.

[kingtal0n]

well it shouldn't be that hard. The arduino takes ADC input which is analog to digital. It also has dedicated 5v output. That means a 1-bar map can run right off the arduino, it won't pull enough current to cause any issue iirc. The ADC directly detects voltage converts to digital count.

Then its just the output to the relay which controls your-whatever. fuel pumps, meth pumps, anything electrical from a relay right? So the Arduino can be used as a ground trigger or current trigger. I Like current trigger using 2N2222 but the sensitivity with 12v automotive relays is hit or miss when using just 1 transistor, so simply use a pair of 2N2222. Its called darlington pair configuration. I have good success using them like that.

So the arduino senses ADC from the map which is powered by the arduino in a closed curcuit. You power the arduino using automotive 10v-15v input so the 5v output is stable and reliable, the map won't wander on the input. Put a inductor on the supply for the arduino to prevent transient voltage spikes from damaging the microcontroller also. Then the output of the arduino goes 'up' 5v to trigger the darlington pair and that flips your automotive relay on or off at 12v. Thats why you need the darlington pair, apparently its hard to trigger the 2N2222 using a 5V base supply with typical resistors (1k to 2k on the base) when the relay is a 12v automotive style.

The tricky part is the ground scheme for the transistor circuits, in testing I noticed you can't pull the automotive relay on with just an arduino ground. So the emitter of the transistors needs to be tied into the automotive relays ground- not the arduino. Or maybe its both. I can't remember right now how I got it to work consistently. But definetely test the thing outside the vehicle using a 5v supply to the arduino first, and then test it again using a battery 12v car power supply, use 10v , 8v, 12v, try different input voltages to make sure it works no matter what. You don't want to be surprised.

If I get some time I plan to make a video anyways for a fan controller project and this will help show how to activate the relays because relay for fans = relay for everything else pretty much. You measure the internal resistance of the relay to figure out how much current it will pull, they are like 180ohms or something usually and always calculate max voltage current, I think 180ohm at 15v is 15/180 = 83mA? And worst case is like 16/120 = 135mA? The 2N2222 will handle up to around 1000mA so its plenty of sink. Haven't played with it in a while though I could be forgetting something. You have to look up the transistor data sheet and find the minimum current to pull the transistor open from the base, there are minimums for everything actually, it should all be calculated in advance I just don't do it often enough to know off the top of my head right now. Looking to finish a video by the end of the year so don't hold ur breath on that either rofl but it can definitely be done, I have a couple finished projects just waiting to be soldered, I'm just busy doing other stuff.

[evilstuie]

Cool, I'll take a look.

I'm assuming the programming is pretty simplistic with this with an if/then ground unground type statement to run it all?

[kingtal0n]

First make an account on Arduino.cc
Look at the example codes in the web editor.

There are hundreds of examples, just use the one that shows manipulating outputs and inputs.

I teach college engineering freshmen this stuff every year, 16 to 18 year old can do it, I think anybody can do it. Just have patience.
I am a doctor of engineering at university.

Here is an example of when I started learning arduino to make my first fan controller.
https://forum.arduino.cc/t/arduino-n...ions/620615/13

There is some example code about halfway down. I don't keep the code on this computer or I would copy/paste more of it.

If you'd like I am sending out a bunch of arduinos for students and people interested in monitoring their crankcase pressure,
https://www.corvetteforum.com/forums...post1605233949

I can send you a free arduino and a breadboard and some wiring stuff and some transistors to get you started. Then you can always ask me post here or PM me whatever I will guide you the rest of the way.

Your servant, thanks

[evilstuie]

Thanks for the offer, but I'm over in Australia so it'd cost you a bit in postage!

Arduino will come in handy for lab automation in my work so I should be able to convince them to pay for a few startup kits to learn on and get me sorted

First make an account on Arduino.cc
Look at the example codes in the web editor.

There are hundreds of examples, just use the one that shows manipulating outputs and inputs.

I teach college engineering freshmen this stuff every year, 16 to 18 year old can do it, I think anybody can do it. Just have patience.
I am a doctor of engineering at university.

Here is an example of when I started learning arduino to make my first fan controller.
https://forum.arduino.cc/t/arduino-n...ions/620615/13

There is some example code about halfway down. I don't keep the code on this computer or I would copy/paste more of it.

If you'd like I am sending out a bunch of arduinos for students and people interested in monitoring their crankcase pressure,
https://www.corvetteforum.com/forums...post1605233949

I can send you a free arduino and a breadboard and some wiring stuff and some transistors to get you started. Then you can always ask me post here or PM me whatever I will guide you the rest of the way.

Your servant, thanks

[Alvin]

Hi All,

I've got an issue with my brakes that requires some auxiliary vacuum which I've decided to use a UP28 electric pump. I also got the Bosch# 20876799 vacuum switch to turn it on and off, but I thought this would be a simple, 12v output to a relay to switch on and off when the vacuum pressure was out of range.

Turns out it is controlled by the PCM on cars like the VF commodore and E39a PCMs using a 5v reference, low reference and signal wire.
Assuming the switch output is 0-5v, is there any table I could utilise in the HPT SD OS that could send a 12v or ground signal to a relay to kick the pump on and then off when it reaches a certain voltage?

I'm already using EGR for my wideband, but was thinking possible the EVAP controls or something similar?

I'm just looking to find if there's a way I can do it without going and buying a $100 12v vacuum pressure switch.

This is way to simple of a project to get an arduino involved.

You can get a hobbs switch and have it trigger in vaccum, little boost, whatever. Most are adjustable.

https://www.google.com/search?q=hobb...hrome&ie=UTF-8

[evilstuie]

This is way to simple of a project to get an arduino involved.

You can get a hobbs switch and have it trigger in vaccum, little boost, whatever. Most are adjustable.

https://www.google.com/search?q=hobb...hrome&ie=UTF-8

If you read the last line of the post you quoted I was looking to avoid paying $100 (The lowest price I was able to find including buying from the US and shipping to Australia) for the vacuum switch.

The Arduino solution is slightly more complicated than just putting in the switch but I'd rather pay the cost of the hardware and time to learn it than pay out $100 for an overpriced switch.
That's just me though. If I could find one for $40 then I'd get that, but everything is way too overpriced here in Aus, and shipping from the states usually costs more than the part is worth.

[Alvin]

If you read the last line of the post you quoted I was looking to avoid paying $100 (The lowest price I was able to find including buying from the US and shipping to Australia) for the vacuum switch.

The Arduino solution is slightly more complicated than just putting in the switch but I'd rather pay the cost of the hardware and time to learn it than pay out $100 for an overpriced switch.
That's just me though. If I could find one for $40 then I'd get that, but everything is way too overpriced here in Aus, and shipping from the states usually costs more than the part is worth.

That's bananas.. Ebay is full of them for $25 or less.

[kingtal0n]

Also why not just turn on the vacuum pump whenever you step on the brake? Whether it needs or not. You can use brake light trigger a relay and done.

I like arduino because you can add a LCD screen and attach other relays, monitor temperatures, etc... its a handy feature. I even use for security, a little pad, enter a number or it locks out the neutral SS and fuel pump relay. You could even go so far as to have it blow a ign based fuse in the event of tampering for a permanent kill switch nobody can ever find or figure out. I use two arduinos... one is easy to see, "hey tamper with me" and the other is hidden, watching the first one. Hell lets add a shaped charge to the ECU so if somebody takes the car it blows a hole right through the memory chips. Yeah... The possibilities are limitless....

[evilstuie]

car.jpg

That's bananas.. Ebay is full of them for $25 or less.

Yep, then add $50 for shipping to Australia.
It's complete bullshit.
Most of the results won't even show up on Australian ebay because the sellers won't internationally ship

Also why not just turn on the vacuum pump whenever you step on the brake? Whether it needs or not. You can use brake light trigger a relay and done.

I like arduino because you can add a LCD screen and attach other relays, monitor temperatures, etc... its a handy feature. I even use for security, a little pad, enter a number or it locks out the neutral SS and fuel pump relay. You could even go so far as to have it blow a ign based fuse in the event of tampering for a permanent kill switch nobody can ever find or figure out. I use two arduinos... one is easy to see, "hey tamper with me" and the other is hidden, watching the first one. Hell lets add a shaped charge to the ECU so if somebody takes the car it blows a hole right through the memory chips. Yeah... The possibilities are limitless....

Yeah that's the biggest advantage. The car is a Knight Rider "replica" of sorts. Not exact replica but my own imagining of it including an updated dash that runs a car PC, 24" touchscreen for the center of the dash, portrait mode, another 20" screen for the passenger side, and eventually android tablet to run the gauges.
Arduino will definitely help for getting readings and data I need to tie everything together and convert everything else i need for coms/usb input etc

[kingtal0n]

Hah yeah! the best part IMO is that everything is already done for you. Everybody has done everything there is pretty much. Just a simple search "______ Arduino code" i.e. "Knight rider arduino code" and walaa

https://www.arduino.cc/en/Tutorial/KnightRider

On a silver platter

[evilstuie]

Also why not just turn on the vacuum pump whenever you step on the brake? Whether it needs or not. You can use brake light trigger a relay and done.

I thought about that, but then it's only going to be running when the brake is pressed, so it will only build up vacuum pressure after the fact. Most times when the brake is needed it needs to be instant.

I have a fuel surge tank that I'm not using so I might convert that into a vacuum reservoir which will give me a little more buffer.

[kingtal0n]

Brake booster is supposed to be a vacuum res, has a check valve. Aux vacuum cans are relics from ancient carb days, SBC with huge cams. If you increase the vacuum res capacity with an aux can you might not need a vacuum pump at all anymore. Alternatively maybe your check valve is leaking on the booster causing a low vacuum condition or the brake master itself. I would consider vacuum testing the booster/master/check valve.

It just seems strange to me that the pump running instantly wouldn't sufficiently assist with the pre-existing vacuum in a typical booster. Its such a rare problem leading me to believe there is some issue with a leakage.

[evilstuie]

Brake booster is supposed to be a vacuum res, has a check valve. Aux vacuum cans are relics from ancient carb days, SBC with huge cams. If you increase the vacuum res capacity with an aux can you might not need a vacuum pump at all anymore. Alternatively maybe your check valve is leaking on the booster causing a low vacuum condition or the brake master itself. I would consider vacuum testing the booster/master/check valve.

It just seems strange to me that the pump running instantly wouldn't sufficiently assist with the pre-existing vacuum in a typical booster. Its such a rare problem leading me to believe there is some issue with a leakage.

The pump doesn't provide enough instant vacuum. I did some tests yesterday with a 1L reservoir and the pump can get to 12-15" within a bit under 2 seconds, but to get to 20" it needs about 10 seconds of running.
Granted that may be because it is "filling" the brake booster plus the can, but this will definitely give me piece of mind.

I let it sit overnight from 15" and took a look this afternoon and it was still sitting on 15", so brake booster, lines and check valves are all working correctly.

[kingtal0n]

Well it sure sounds like you know what you are doing. Vacuum test, check. Vacuum reading, check. Vacuum reservoir volume/rate, check? At this point I would tentatively suggest (not sure its worth doing or even possible but it is an lightly engineering consideration) if you're going to go through all the trouble of increasing the vacuum capacity using external reservoir: Perform some calculation to find out roughly how much pressure and how much volume the brakes use per 'stroke' in a worst case scenario and determine the necessary volume for each available pressure scalar. For example 12" with 2L capacity might work for 3 full braking strokes but 18" with 1.5L might also work similarly. Then you could find the minimum volume which would maximize the pressure signal per unit mass evacuated from the reservoir. In other words pressure drop derivative (rate of change) is maximized at some minimum volume given a constant flow rate supply source. The vacuum pump for example would much more quickly supply 18" to a small reservoir than a large one, but I am not a braking expert and no idea how the pressure vs volume plays a role at the pedal feel and braking influence. It may respond more favorably to a large volume of mediocre pressure or a small volume of very low pressure. Thats where the arduino comes into play- you can test various MAP start points for the pump and find the ideal setting with minimum pump run-time (wear) much easier done empirically than mathematically I guess.

[evilstuie]

ok, so I'm about to head to Jaycar (our version of an electronics/hobbyist store) and grab some bits for this and just wanted to see if these 2 components would cover me for the build:
https://www.jaycar.com.au/duinotech-...board/p/XC4410 (Arduino controller)
https://www.jaycar.com.au/arduino-co...odule/p/XC4440 (12v relay control)

I'll tie this into the 12v and grounds from the car, and then program the arduino to monitor the voltage from one of the 5 analog in channels to trigger the Arduino relay to trigger the 12v automotive relay to trigger the vacuum pump.
When the pump hits desired vacuum (voltage), the relay shuts off.

Would this setup avoid the issue you mentioned with the Arduino not triggering the automotive relays?

[Alvin]

Be careful powering them up straight off the cars power supply. Voltage spikes and noise in general can/usually give problems.

If you search "automotive power supply arduino" you'll find ways around it. It's not end of the world but does matter.


I've built a few things using Atiny85's (programmed with arduino ADE) for cars, drones, and actually fishing stuff lol.

[evilstuie]

Be careful powering them up straight off the cars power supply. Voltage spikes and noise in general can/usually give problems.

If you search "automotive power supply arduino" you'll find ways around it. It's not end of the world but does matter.


I've built a few things using Atiny85's (programmed with arduino ADE) for cars, drones, and actually fishing stuff lol.

https://www.jaycar.com.au/arduino-co...494d78d5cd5e7e

Problem solved?

I do like the fact that so far any issue or requirement is solved with a premade module