4piknup
master of none
Ic108 is jist a small relay (actually 2 relays) all it does is joins a wire to earth when the ecu tells it. Like a relay, it has 4 wires to do this. There is the switched input and output and the control input and output.
fuel pump constantly priming
- Thread starter mathew_colville
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4piknup
master of none
So, pins 1-4 is the aircon side and pins 4-8 is the fuel pump side. So power comes from the white/red wire (from the switched side of the mfi relay) into ecu pin8 and travels to ic108 pin7 (you checked this connection) when the ecu puts power onto pin2 and pin6 (pin2 is shared on both sides) then power will flow from pin7 through ic108 and out pin4 to earth, so switching the fuel pump side of the mfi relay and turning pump on.
So if I was looking more into it, I would change out the ic108 and add a chip holder so I can test the pins from the top of board. Then need to fit the ecu and while cranking engine need to look at what is happening on pin2 and pin6. I think there is a problem with power there, so them start tracing the ecu board back to the transistors and power feeds thatgo to pins 2 and 6.
If your aircon works (I dont know what function ic108 has on aircon) maybe pin2 is fine and the issue is pin6 related.
Or add to my test bench and dummy rig it to run a ecu and wire in a cas.
We looked at the other pin combinations as this tests the transistors inside the ic108. They were not blown or shorted so appear fine.
You can google the m5269L and get the tech sheets to see inside the ic108.
You can google 'darlington pair' as ic108 has 2 darlington pairs (pin1-4) and (pin 4-8)
So if I was looking more into it, I would change out the ic108 and add a chip holder so I can test the pins from the top of board. Then need to fit the ecu and while cranking engine need to look at what is happening on pin2 and pin6. I think there is a problem with power there, so them start tracing the ecu board back to the transistors and power feeds thatgo to pins 2 and 6.
If your aircon works (I dont know what function ic108 has on aircon) maybe pin2 is fine and the issue is pin6 related.
Or add to my test bench and dummy rig it to run a ecu and wire in a cas.
We looked at the other pin combinations as this tests the transistors inside the ic108. They were not blown or shorted so appear fine.
You can google the m5269L and get the tech sheets to see inside the ic108.
You can google 'darlington pair' as ic108 has 2 darlington pairs (pin1-4) and (pin 4-8)
khubner1
Moderator
Perhaps it's a track issue between ic108 and earth
4piknup
master of none
Ic108 pin4 shares a track with all other ic drivers in the row. Check continuity from pin4 to other pin4 and earth.
Thanks k.
Thanks k.
mathew_colville
Well-Known Member
ok i checked the continuity, everything seemed fine, so i was fiddling around pretending i knew what i was doing
i was in this area here
did this:
the clip hit pin 8,9,10, wasnt connected to the multimeter, had the ignition turned on and the fuel pump turned on, now if i removed the clip the fuel pump would keep going until i tried to start the car then it would turn off preventing car from starting
if i leave the clip on, touching pin 8,9,10 the car will start and then i can remove clip when car is running and the pump will stay on
so does this help to solve the problem in anyway?
now the bad part: i went to clip it on the 3 pins to get my car going, it was a little dark and i may have put it on pin 7,8,9 instead of 8,9,10 (im not sure)
so now i have no power what so ever, car is completely dead! does the ecu have a fuse? if so where do i find it or did i just fry my ecu :fuuuuu:
i was in this area here
did this:
the clip hit pin 8,9,10, wasnt connected to the multimeter, had the ignition turned on and the fuel pump turned on, now if i removed the clip the fuel pump would keep going until i tried to start the car then it would turn off preventing car from starting
if i leave the clip on, touching pin 8,9,10 the car will start and then i can remove clip when car is running and the pump will stay on
so does this help to solve the problem in anyway?
now the bad part: i went to clip it on the 3 pins to get my car going, it was a little dark and i may have put it on pin 7,8,9 instead of 8,9,10 (im not sure)
so now i have no power what so ever, car is completely dead! does the ecu have a fuse? if so where do i find it or did i just fry my ecu :fuuuuu:
mathew_colville
Well-Known Member
4piknup
master of none
Oops. Now youve done it.
It might be the ecu earth has a blown track. I think its over by the other end of the ecu plugs, near the screw.
I dont know why you think randomly connecting wires in the ecu could fix your problem. I have no idea what might have blown.
Does it smell like its burnt now?
It might be the ecu earth has a blown track. I think its over by the other end of the ecu plugs, near the screw.
I dont know why you think randomly connecting wires in the ecu could fix your problem. I have no idea what might have blown.
Does it smell like its burnt now?
4piknup
master of none
Pin9 isnt alarm its something else.
You may have cooked the ign amplifier. I dont knoe anything about it or how it works.
You may have cooked the ign amplifier. I dont knoe anything about it or how it works.
evo-gsr
Well-Known Member
Oh ohhhh....
khubner1
Moderator
pin 9 is the evap canister purge
4piknup
master of none
Thats why the pump was running. It was piggy backing onto evap purge. Ic106 (or whatever one it is)
mathew_colville
Well-Known Member
ok so it was only a fuse, swapped the main fuses over and everything is back to how it was
so it was piggy backing off ic106 until the car started then the pump would keep going after the clip was removed, does this mean that the circuit is fine? that all transistors are ok? or once the pump is running does the ecu stop controlling it and its controlled by something else?
it needs to be the part that tells the pump when to turn on? is that the ic108 driver? is it a certain pin on it? or is it not the driver?
so it was piggy backing off ic106 until the car started then the pump would keep going after the clip was removed, does this mean that the circuit is fine? that all transistors are ok? or once the pump is running does the ecu stop controlling it and its controlled by something else?
it needs to be the part that tells the pump when to turn on? is that the ic108 driver? is it a certain pin on it? or is it not the driver?
4piknup
master of none
Lucky you.
This is beyond my experience now.
You need a test bench and a oscilloscope.
Ic108 pin2 I think is like a pushstart.
Ic108 pin6 is switched by the ecu, that turns the first transistor on, then pin2 senses that the first is on and turns the second transistor on. (Not really sure but)
Look up darlington pair. It will explain.
This is beyond my experience now.
You need a test bench and a oscilloscope.
Ic108 pin2 I think is like a pushstart.
Ic108 pin6 is switched by the ecu, that turns the first transistor on, then pin2 senses that the first is on and turns the second transistor on. (Not really sure but)
Look up darlington pair. It will explain.
mathew_colville
Well-Known Member
hehe im the sort of person who does something and then goes... hmmm maybe i shouldnt have done that, my wife is always getting angry at me for doing silly things 
anyway i wasnt to worried as id planned to get a working ecu at some stage, just would have had been alot sooner if it was fried lol
if the next step is beyond your experience then its definitely beyond mine, I wouldnt have been able to get this far in diagnosing it without you, at the start i was gonna stick the multimeter in each ear and see if the old brain circuit was working haha
anyway as ive said before i really appreciate you guiding me through what you know and trying to help me Jack of all, if theres ever anything i can do to help you out just let me know and to the other members who also helped out thanks
At this stage i am going to set up my fuel pump like evo-00x posted a while back, so it at least has a fuse in it and also a kill switch of some sort, should do until i get a new ecu
anyway i wasnt to worried as id planned to get a working ecu at some stage, just would have had been alot sooner if it was fried lol
if the next step is beyond your experience then its definitely beyond mine, I wouldnt have been able to get this far in diagnosing it without you, at the start i was gonna stick the multimeter in each ear and see if the old brain circuit was working haha
anyway as ive said before i really appreciate you guiding me through what you know and trying to help me Jack of all, if theres ever anything i can do to help you out just let me know and to the other members who also helped out thanks
At this stage i am going to set up my fuel pump like evo-00x posted a while back, so it at least has a fuse in it and also a kill switch of some sort, should do until i get a new ecu
mathew_colville
Well-Known Member
Does this seem like it would work on my car, any issues anyone can see?
-How do you keep an electric fuel pump safe?
Electric fuel pumps can be dangerous?
Yep, without some way to automatically shut them off, they can be VERY dangerous.
But they don't have to be.
If something lets go in your engine bay like a fuel line, the engine will eventually quit. However, if you don't have a way to automatically shut off your electric fuel pump you will keep spraying raw fuel all over your hot engine and wiring.
Also, in a crash, your pump can continue to run feeding a fire if you don't have a way to stop it.
Note: Never mount an electric fuel pump in an enclosed area such as the trunk or interior space...
Ok, so how do I do it right?
The easiest way is to use an oil pressure switch. The switch will stop the pump whenever the oil pressure in the engine goes away. So, whenever the engine is off, the pump will turn off automatically.
Some switches just do that. But how do I get the pump to run when I'm trying to start the motor and the oil pressure's not up yet?
You use a three prong switch like this Standard Ignition PS-64:
The switch will also let the pump run when you hit the starter because the engine doesn't have oil pressure yet.
One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump. When the oil pressure comes up, the switch connects IGN to PUMP, for normal running. When oil pressure goes away (because you just hit that rock and tore the pan off the engine, for example) it again connects START to PUMP, and disconnects IGN from PUMP, so the pump shuts off.
-How do you keep an electric fuel pump safe?
Electric fuel pumps can be dangerous?
Yep, without some way to automatically shut them off, they can be VERY dangerous.
But they don't have to be.
If something lets go in your engine bay like a fuel line, the engine will eventually quit. However, if you don't have a way to automatically shut off your electric fuel pump you will keep spraying raw fuel all over your hot engine and wiring.
Also, in a crash, your pump can continue to run feeding a fire if you don't have a way to stop it.
Note: Never mount an electric fuel pump in an enclosed area such as the trunk or interior space...
Ok, so how do I do it right?
The easiest way is to use an oil pressure switch. The switch will stop the pump whenever the oil pressure in the engine goes away. So, whenever the engine is off, the pump will turn off automatically.
Some switches just do that. But how do I get the pump to run when I'm trying to start the motor and the oil pressure's not up yet?
You use a three prong switch like this Standard Ignition PS-64:
The switch will also let the pump run when you hit the starter because the engine doesn't have oil pressure yet.
One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump. When the oil pressure comes up, the switch connects IGN to PUMP, for normal running. When oil pressure goes away (because you just hit that rock and tore the pan off the engine, for example) it again connects START to PUMP, and disconnects IGN from PUMP, so the pump shuts off.
4piknup
master of none
That will work. Nissan use similar. You can just use it like is and car wont start till you have oil pressure.
If you wanted to do this you could run the white/red wire to the oil idiot light sender on engine. Not sure if you need a diode or if you can run the light and the pump together.
My mates nissin only starts after it gets oil pressure, it doesnt crank for long before it fires up.
Your 3 pin switch will be a bit different.
Id maybe run the thin wire on the starter to the sender. And the fuel pump wire from the fuse box (after the fuse), split that and run it to the sender.
Also , just earth the white/red wire as you are now positive switched not negative switched.
Id try the first setup first.
Unplug the oil light at the sender and plug the white/red wire in. Easy. I dont know why I didnt think of that.
If you wanted to do this you could run the white/red wire to the oil idiot light sender on engine. Not sure if you need a diode or if you can run the light and the pump together.
My mates nissin only starts after it gets oil pressure, it doesnt crank for long before it fires up.
Your 3 pin switch will be a bit different.
Id maybe run the thin wire on the starter to the sender. And the fuel pump wire from the fuse box (after the fuse), split that and run it to the sender.
Also , just earth the white/red wire as you are now positive switched not negative switched.
Id try the first setup first.
Unplug the oil light at the sender and plug the white/red wire in. Easy. I dont know why I didnt think of that.
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