help! s5 ECU wiring
 

Hey Guys, I am just about done with swaping a s5 N/A motor in my fb and I have run into some problems with the wiring.

I have confirmed that I have power going to all the proer terminals but I cant get any spark at the coils.

Now this harness has been stripped down to just the wires for the ECU.

What would prevent the ECU from giving power to the coils? Does it go through some kind of check first?

umm.. the main relay?

oops... I just noticed you had an N/A. that is a turbo pic but the coil setup is the same.


http://www.1300cc.com/wiring/elec_z32.jpg

Yep I have have a signal from the main relay, the igntition switch and the constant from the battery.

The only thing that I can think of is that the circuit is not complete somehwhere, or that it has to go through some checks.

A few points that might be important about my setup are:

• I do not have my Fuel Pump being run through the fuel pump resistor and relay. I have it connected just to the ignition switch as it is connected in the carburated FB's
• My clutch switch is not fucntioning properly, the motor still turns over however, with or without the ECU plugged in
• The second connector on the water pump housing that is exclusive to the S5's is not connected becaus the connector broke off. This shouldnt be relivent to why I am not getting spark at the coils however.
• All unimportant Items from the ECu have been disconnect and removed as I do not need them for my car. These would be things like the headlights and foglights. The FB does not require the ECU for these items to work
• I also do not have my oil level sensor and pressuer sensor connected yet. I plan on cennecting these in the next few days, but I dont see how this would be preventing me from starting unless they are required by the ECU somehow.
• The last one is that my transmission does not have a neutral switch. I dont know if this would cause a problem as well.

If anybody has any ideas or suggestions on what to check or if any of the information in my setup is causing a problem that would be greatly appreciated!

I presume you are using the S5 igniters & coils?

Yep its the stock S5 ignitors and coils. I just checked and I have power going to the coils, and I have some voltage leaving the ECU at the terminals when the key is in the on position but not cranking.

Could be the way I am running my fuel pump have any problem? It looks like i'm just not using the whole circuit opening relay, which I dont know if that would prevent the ECU form letting the coils fire.

Anyone else have any ideas?

if you have power at the coils, but it's not sparking. I would be looking at the CAS and it's wiring.

I checked the crank angle sensor, and all four pins on the harness side of the crank angle sensor plug appear to be grounds.

I'm not sure if that is normal or not. However, this is on the other side of the harness, and that harness was not modified.

My strong suspesion right now is the circuit opening relay and fuel pump relay/resistor. Again these were not connected as I have my fuel pump connected directly to my igntion switch, but that may very well be the reason its spazing out on me.

As I wont be able to work on my car untill monday, would somebody mind checking if there is still spark to the plugs if the circuit opening relay or fuel pump resistor/relay is unplugged?

bump

bump again

could someone check please? (bump) :)

I don't think the fuel pump has anything to do with getting spark.

have you tryed looking for ecu codes?

the reason why I would think that it would is because of the circuitit opening relay.

Couldnt the ECU be looking for a signal from the circuiting opening relay and possible the fuel pump resistor relay before it allows the coils to spark?


ECU codes... it could be helpful, but I dont really know how to go about that, and I'd think that it would be shooting other bizare codes at me for all the other stuff I removed from the ECU like the head lights and stuff. But anythings worth a shot. What would I need to do to obtain the codes from the ECU?

did u take the plugs out an watch them not spark(while connected, but laying on the engine)?

or are u jus guessin that they dont spark because the engine doesnt turn over?

are you sure the engine is getting fuel?

absolutely sure its not sparking.

I tried using a timing light, and sticking a screwdriver in one of the plug wires to see if there was any spark. Absolutely nothing.

Now the engine may very well not be getting fuel, and if it isnt I should still get some reaction from a timing light. I'm connecting the fuel pump behind the relay the way it was desigened to be in the fc rather than the way it's powered in the FB which is just getting a power lead from the ignition switch when its in the on position.

Now heres something I'd like to confirm. When I was checking the plug of my crank angle sensor on friday, all of the pins on the harness side were grounds. I used a voltmeter to confirm this. Should all four of the pins be grounds?

umm I doubt it.... maybe they are shorted out. my guess is the CAS or wiring is your problem as metioned above. fuel pump shouldn't effect getting spark in anyway.

if you look in the above pic. you will see all 4 go to the ecu...

Well if you look at the voltage and pinout sheet for the ECU it shows that some if not all the connections to the crank angle sensor are a negative signal which would imply a ground.

I'm going to wire up the circuit opening relay, and the fuel pump reistor/relay tomorrow. If that doesnt work I'll try running some new wires to the crank angle sensor to make sure they arent shorted out.

If that doesnt work, you suggested that the crank angle sensor may be bad. Is there anyway to test it?

Again my only reason for suspecting the fuel pump is that the ecu might be trying to check that it has connections to all the nessacarey sensors before it gives the signal to the ignitors to spark. The only real way of finding that out sort of trial and error would be to look at a schematic for the ECU itself. Has there ever been one released for the S5 ECU?

Yes pull the codes. You may get more codes because of your modifying the harness but if there is a problem it will list that one too. If nothing else pulling the codes will let you know the ECU is alive. There is instructions out there. I don't have any links handy.

My guess is there is something else wrong.

Oh piddle. You have no spark. Are you sure. Put your hand on the engine and a finger on the end of one of the Lead plug wires. Make sure the other Lead plug is connected to its plug. Now have someone spin the engine. NO tingle?

If you have 12v on the black/yellow wire at the two socket connector for the Lead coil assy, its powered up and just needs a trigger from the ECU.

One fellow on this site had the same symptoms. He forgot to connect the ECU grounds up. They're located under the intake body.

CAS wires reading to ground??? Not likely. Put the negative lead of the meter on a good ground, such as the cigar lighter body or one of the bolts that hold the ECU in place. Put the other lead on each of the wires that go to the CAS one at a time with the meter on ohms. Still show a ground??? Like .000 ??? CAS are almost bullet proof. Not likely.

If you are checking the cas out, your checking the coils in the cas. If on a series four you'd be putting one lead of the meter on pin 1N and the other on pin 1P and looking at the resistance. Then you'd go to pin 1T and 1Q and do the same as before. They should read approx the same.

You know the ECU plugs are read from the back of the plugs where the wires enter the connector? And you read from right to left, first the top right, then the right bottom and progressively work your way to the left of the plug?

The ECU does not look at the fuel pump relay etc to decide if it's gonna give spark to the plugs.

One of my favorite thoughts on determining if the ECU has gone tits up, is to have all the plugs on the ECU. Then put the meters neg lead on a good ground. Then turn the key to on. Insert the positive lead in the back of pin 2C. You should have approx 4.5 volts. If not, the reference voltage output device has gone away/burnt up. If you see no 4.5 volts there, the coils will never, never, ever spark.

Skip most of the above and look for the voltage on pin 2C first. If it ain't thar, no sense wasting your time with anything else til that gets resolved.

Well fudge. A series five harness. Missed that. Functional illiterate here. Same principles though as stated above, but different ECU pin numbers. Look at pin 2A for the reference voltage of approx 4.5 volts.

At the ECU read ohms from pin 3G to 3H. Should be approx 110 to 210 ohms. Then read 3H to 3E. Approx the same results. Thats with the plug off lookin back to the cas. Neither wire/pin should be grounded. That's to check the coils inside the CAS out.

You might make sure the trigger wire runs from the G/Y wire at the Lead coil small white plug, back to the Pin 1H at the ECU.

Stripped down harness. Hmmmmm. You might make sure the ECU is getting its 12v at pin 1A, 1B,3W, 3X, 3Y, 3Z, all with the key to on.

Grounds at pins 3A, 3B, 3C, 3D. Those should be there all day long. Key off helps, not required.

I'm still a big fan of looking at pin 2A for 4.5 volts to help determine if the ECU is good or not.

are you sure its pin 2a?

The manual says that connects to the electric oil metering pump, and is off when the key is in the off position and around 1 volt when the engine is at idle.

I connected the circuit openeign relay and fuel pump resistor relay and no luck there.

I tried running new wires from the ECU to the CAS and still no luck. Also all those wires still worked as a ground. I tested this by taking a voltmeter and putting the positive end on the positive end of the battery and using the negative to contact the pins. Every one of them read 12 volts with or without the new wires.

I'm beginning to think that that is where the problem lies as it doesnt make any sence why all the pins on the CAS would work as grounds. I'm stumped here....

And as for the code checking, I removed those connecteors on the dirvers side harness becuase I thought it would require some expensive code checker to make use of the plugs so I removed them. I still have a little bit of the wire on my ecu though.

Where should I go from here? BTW I'm going to try those voltages tomorrow, thanks hailer!