No Power to the ECU
10-21-07, 05:06 PM
#1
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No Power to the ECU
the ecu isn't comming on.... when i check the pin for the battery there is 0V its sappose to be a constant 12V's
what would interupt the power from the ecu is there a fuse or something i',m missing
the ecu isn't comming on at all....theres no spark and the injectors aren't firing
what would interupt the power from the ecu is there a fuse or something i',m missing
the ecu isn't comming on at all....theres no spark and the injectors aren't firing
10-22-07, 01:05 AM
#2
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Assuming you're checking the right pin...
The ECU's constant power comes from the 7.5A ROOM fuse in the interior fuse box. If it's blown the interior lights won't be working either, so if they're okay it's not the fuse.
How do you know the ECU isn't "coming on"? There are no lights or anything to tell you. Have you checked the EGI fuses in the engine bay?
The ECU's constant power comes from the 7.5A ROOM fuse in the interior fuse box. If it's blown the interior lights won't be working either, so if they're okay it's not the fuse.
How do you know the ECU isn't "coming on"? There are no lights or anything to tell you. Have you checked the EGI fuses in the engine bay?
10-22-07, 01:31 AM
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Assuming you're checking the right pin...
The ECU's constant power comes from the 7.5A ROOM fuse in the interior fuse box. If it's blown the interior lights won't be working either, so if they're okay it's not the fuse.
How do you know the ECU isn't "coming on"? There are no lights or anything to tell you. Have you checked the EGI fuses in the engine bay?
The ECU's constant power comes from the 7.5A ROOM fuse in the interior fuse box. If it's blown the interior lights won't be working either, so if they're okay it's not the fuse.
How do you know the ECU isn't "coming on"? There are no lights or anything to tell you. Have you checked the EGI fuses in the engine bay?
10-22-07, 07:10 AM
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Actually the ECU does not NEED this Batt pwr on 3J to run the engine. It is fed by the Room fuse. That Room fuse is in turn fed from the BTN fuse in the engine bay.
You should remedy the lack of pwr on 3J. Pin 3I should have 12vdc from the main relay. Gotta have that. Should have both.
Room fuse feeds things like the interior spot light, courtesy lights, cargo room light, in other words lights that some of us might never miss in life. NOT things like headlights/side lights etc. Their on another fuse.
You should remedy the lack of pwr on 3J. Pin 3I should have 12vdc from the main relay. Gotta have that. Should have both.
Room fuse feeds things like the interior spot light, courtesy lights, cargo room light, in other words lights that some of us might never miss in life. NOT things like headlights/side lights etc. Their on another fuse.
Last edited by HAILERS; 10-22-07 at 07:25 AM.
10-22-07, 10:40 AM
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that fuse was blown ....but no luck still
I think the ecu might be toast
i have no fuel or spark....if anything the injectors should fire
when i got the ecu there was a broken resistor in it i soldered back in ....something else must be messed up......i'm goin to try and pick up another S5 ecu off ebay for cheap and just switch the EPROM from my tom's ecu and put it in the other one...its pretty basic
is there test i could do to see if the ecu is working....i don't think its even comming on
when i leave the #3 plug in with the power it is getting power now....i get 1-4 volts on the #1 an #2 plug pins so would there what at the very least could keep it from firing the injectors or giving me spark
I think the ecu might be toast
i have no fuel or spark....if anything the injectors should fire
when i got the ecu there was a broken resistor in it i soldered back in ....something else must be messed up......i'm goin to try and pick up another S5 ecu off ebay for cheap and just switch the EPROM from my tom's ecu and put it in the other one...its pretty basic
is there test i could do to see if the ecu is working....i don't think its even comming on
when i leave the #3 plug in with the power it is getting power now....i get 1-4 volts on the #1 an #2 plug pins so would there what at the very least could keep it from firing the injectors or giving me spark
Last edited by FC3Sdrift; 10-22-07 at 10:55 AM.
10-22-07, 11:02 AM
#7
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Tell me if this sounds plausible to anyone.....
i left the S5 wiring for the crank angle sensor alone because it runs through the engine harness.... and left the coil packs wiring alone with the S4 chassis harness......i should have used the wires for the S4 crank angle sensor so they are all connected in one complete circuit
i know that on my other car i can fire the injectors by spinning the distributor....
they must have to be all together in one circuit so the ecu will get the right information
i'll try switchin those wires and see what happens
i'm pretty sure the ecu is working now
i left the S5 wiring for the crank angle sensor alone because it runs through the engine harness.... and left the coil packs wiring alone with the S4 chassis harness......i should have used the wires for the S4 crank angle sensor so they are all connected in one complete circuit
i know that on my other car i can fire the injectors by spinning the distributor....
they must have to be all together in one circuit so the ecu will get the right information
i'll try switchin those wires and see what happens
i'm pretty sure the ecu is working now
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10-22-07, 02:04 PM
#9
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If you have spark then your fuel injectors should have also operated when the the cas was spun.
Check the fuel injector plugs for 12vdc. One wire on each plug is power. The other wire on the injector goes to the ECU and the ECU pulses a gnd to that wire to operate the injector.
So go to the ECU and see if all four fuel injector wires have 12vdc when the key is to ON. I'm a little lost on what car/what engine/what harnesses are involved on your car. Are you using a series four EM harness on the engine????? Or a series five EM harness on the engine???? The EM harness has two yellow plugs on it just on the passengers side of the firewall. These do NOT connect to the ECU. They connect to the FRONT harness. They supply the 12v for the injectors and 12vdc for the solenoids and that 12vdc to the ECU. Plus wipers, cruise signals, and Stuff to many to mention.
Check the fuel injector plugs for 12vdc. One wire on each plug is power. The other wire on the injector goes to the ECU and the ECU pulses a gnd to that wire to operate the injector.
So go to the ECU and see if all four fuel injector wires have 12vdc when the key is to ON. I'm a little lost on what car/what engine/what harnesses are involved on your car. Are you using a series four EM harness on the engine????? Or a series five EM harness on the engine???? The EM harness has two yellow plugs on it just on the passengers side of the firewall. These do NOT connect to the ECU. They connect to the FRONT harness. They supply the 12v for the injectors and 12vdc for the solenoids and that 12vdc to the ECU. Plus wipers, cruise signals, and Stuff to many to mention.
10-22-07, 02:08 PM
#10
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The series five JDM fuel lines hook up OPPOSITE to the USA series four cars. Pull the front fuel line off and turn the key to Start for a brief moment. Fuel should gush out. IF not, the fuel lines MIGHT be on *** backwards.
Another thing to try. Disconnect the small white plugs to the ignitors. Spin the cas with the key to ON. You SHOULD hear the fuel injectors clicking. I can. If so, then the problem is probably the fuel lines on assbackwards. No clicking? Electrical is missing from the injectors. Check for batt voltage at the four injector wires at the ECU plug if that's the case.
Another thing to try. Disconnect the small white plugs to the ignitors. Spin the cas with the key to ON. You SHOULD hear the fuel injectors clicking. I can. If so, then the problem is probably the fuel lines on assbackwards. No clicking? Electrical is missing from the injectors. Check for batt voltage at the four injector wires at the ECU plug if that's the case.
10-22-07, 03:13 PM
#11
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A little mistake has been made. Remove the aft fuel line off the engine and go to Start momentarily and see if fuel comes from the engine side of the line. No fuel means the lines MIGHT be on backwards for a JDM engine.
10-22-07, 10:58 PM
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i'm getting fuel now ....no spark
i have to try some stuff tomorrow
on a S4 there are 4 wires for the CAS goin to the ecu but on the S5 there's 3
so the 4th must be tied into something else in the engine harness....i'm goin to try and route that wire back through the S5 engine harness
i definately have fuel though thats half the battle
for the fuel lines i didn't know which was which so i just saw what line ran of the FPR and new it was the return line
plus on the other one it branches off to the fuel rail ontop of the dynamic chamber
i have to try some stuff tomorrow
on a S4 there are 4 wires for the CAS goin to the ecu but on the S5 there's 3
so the 4th must be tied into something else in the engine harness....i'm goin to try and route that wire back through the S5 engine harness
i definately have fuel though thats half the battle
for the fuel lines i didn't know which was which so i just saw what line ran of the FPR and new it was the return line
plus on the other one it branches off to the fuel rail ontop of the dynamic chamber
10-22-07, 11:04 PM
#13
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HAILERS I'm using a S41/2 harness hahahahahaha
i took the jdm S5 engine harnessun wrapped it spliced in the two little yellow plugs your talkin about
then on the S4 chassis harness i cut the S4 plug to the ecu and spliced in the S5 plug
the wipers and everything work.....i re wrapped the engine harness ..and got it so the ecu fits in the stock location with only extending the wires for the primary fuel injectors because they were alittle tight under the dynamic chamber
the stock boost guage should even work!
the one thing that caused some of this is that i didn't wire in the s4 plug for the CAS
i think thats the cause of all my problems
i just have to find out where to run that las wire....its gotta tie into something in the engine harness
i took the jdm S5 engine harnessun wrapped it spliced in the two little yellow plugs your talkin about
then on the S4 chassis harness i cut the S4 plug to the ecu and spliced in the S5 plug
the wipers and everything work.....i re wrapped the engine harness ..and got it so the ecu fits in the stock location with only extending the wires for the primary fuel injectors because they were alittle tight under the dynamic chamber
the stock boost guage should even work!
the one thing that caused some of this is that i didn't wire in the s4 plug for the CAS
i think thats the cause of all my problems
i just have to find out where to run that las wire....its gotta tie into something in the engine harness
10-22-07, 11:31 PM
#14
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If memory serves, two of the wires from the CAS come together inside the harness. That's true on the series five. Go look at the series five diagram. On the series four it's not that way. It uses four seperate wires.
When you said you had fuel I thought at first that you meant fuel injectors worked, not fuel pump. If fuel injectors work then the spark would work.
Look at page B1-a of the series five wiring. There are four wires in the CAS. One wire off of each coil in the CAS is spliced to the other inside the series five harness. You could do the same thing at the plug that mates with the ECU. Tie/splice the R and L wires (cas wires) together and have a wire coming off them going to pin 3H on the plug.
The above makes sense when you look at that page B1-a of the series five diagrams.
When you said you had fuel I thought at first that you meant fuel injectors worked, not fuel pump. If fuel injectors work then the spark would work.
Look at page B1-a of the series five wiring. There are four wires in the CAS. One wire off of each coil in the CAS is spliced to the other inside the series five harness. You could do the same thing at the plug that mates with the ECU. Tie/splice the R and L wires (cas wires) together and have a wire coming off them going to pin 3H on the plug.
The above makes sense when you look at that page B1-a of the series five diagrams.
Last edited by HAILERS; 10-22-07 at 11:47 PM.
10-22-07, 11:53 PM
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i could have spark lol i dunno
i think i ended up trying that right at the end
im gonna check to makesure the coils are getting power
what colour is L
i think i ended up trying that right at the end
im gonna check to makesure the coils are getting power
what colour is L
10-23-07, 12:01 AM
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Series five cas wires are White, Green, Red and Blue. They tie Red and Green together inside the harness. Then they go to 3H as one wire.
Series four cas wires are Green, Blue, Red and White. Talking the colors in the harness not inside the cas itself.
Look at both series four and series five diagrams before splicing any wires.
Series four cas wires are Green, Blue, Red and White. Talking the colors in the harness not inside the cas itself.
Look at both series four and series five diagrams before splicing any wires.
10-23-07, 12:05 AM
#19
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AFM has nothing to do with spark. Your on the right trail if you can get the two wires spliced together and installed on 3H and the other two where they go.
No spark and no fuel injection unless the cas works and is tied to the ECU.
At some time, check for approx 5vdc at the afm's plug. A brown/white wire. Same brown/white wire at the boost sensor. IF you don't find the 5vdc at one plug or the other, then there will not ever be any spark. The ref voltage has to be inside the ECU to have spark and fuel pulsing.
No spark and no fuel injection unless the cas works and is tied to the ECU.
At some time, check for approx 5vdc at the afm's plug. A brown/white wire. Same brown/white wire at the boost sensor. IF you don't find the 5vdc at one plug or the other, then there will not ever be any spark. The ref voltage has to be inside the ECU to have spark and fuel pulsing.
10-23-07, 12:09 AM
#20
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Seeing as how it's a series four harness, I'd tie the Blue and the Red together and have them go as one to 3H. Then the Green to 3G and the White to 3E on the series five plug. It is a series five ECU. Right? Right.
10-23-07, 08:12 AM
#22
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i had the red and blue goin to the 3g pin and the green goin 3h
i switched them i'll see how that works....it raining right now so i'll waiy a couple mins to try and start it
i switched them i'll see how that works....it raining right now so i'll waiy a couple mins to try and start it
10-23-07, 08:41 AM
#23
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If you have a spare CAS, you can save a lot of wear and tear on the starter and engine, if you take that spare and connect it to the elect plug that is on the cas on the engine. Then key ON and spin the lower gear on the spare cas and listen for spark/fuel injectors clicking. Once you confirm you have that clicking, then put the elect plug back on the cas on the engine and have a go at it.
You have schematics of the series four and five? In particular the ones showing the wiring to the CAS?
You have schematics of the series four and five? In particular the ones showing the wiring to the CAS?
10-27-07, 01:11 PM
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hey hailers
would a weak signal to the ecu from the main relay keep it from starting
the one problem i have to go back and fix when i got it to start i had a wire goin right from the main relay...because the wire i had goin to the ecu only was getting 4-5V's....the only problem was it wouldn't shut off when i turned the key off until i pulled the wire off the main relay......i never tried it with out that wire till today now its not starting ......i'm getting fuel....and have 12v's at the coils.....but i'm thinkin i'm goin to have to find a full 12v source from the main relay so it gets the full signal...
would a weak signal to the ecu from the main relay keep it from starting
the one problem i have to go back and fix when i got it to start i had a wire goin right from the main relay...because the wire i had goin to the ecu only was getting 4-5V's....the only problem was it wouldn't shut off when i turned the key off until i pulled the wire off the main relay......i never tried it with out that wire till today now its not starting ......i'm getting fuel....and have 12v's at the coils.....but i'm thinkin i'm goin to have to find a full 12v source from the main relay so it gets the full signal...
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