I was atempting to find the tach wire - like a dumbars i tapped into the coil pack....dont ask why i have no idea why i did that.

so now im throwing a 0201 code. below is what that means:

Diagnostic Trouble Code 0201 indicates a problem with the ignition coil and power transistor. The ignition signal from the Engine Control Module is sent to and amplified by the power transistor. The power transistor turns on and off the ignition coil primary circuit. This on-off operation induces the proper high voltage in the coil secondary circuit.

The malfunction is detected when the ignition signal in the primary circuit is not entered during engine cranking or running.

The items to check include
- Harness or connectors (the ignition primary circuit is open or shorted.)
- Power transistor unit built into ignition coil
- Condenser
- Crankshaft Position Sensor (REF)
- Crankshaft Position Sensor (REF) circuit


Did i blow my coil pack? How do I check the power tansistor built into the coil pack?

 

What did you tap into, i.e. what was the signal used for? Un tap it, clear the code, and try again.

 

already did that. i tapped into the purple/white wire (the one that runs from the ECU to the coil pack). Was going to use this for the tach wire - i dont knwo why I know that I was supposed to use the wire off the injector - not coil packs. - cleared the code and it still isnt firing that cylinder.

does anyone know that resistance that the coils are supposed to be?

 

From plugs 1 and 2 it should be 1 ohm. Sux if it is out but you should be able to pick one up in the parts for sale section.

 

http://forums.maxima.org/showpost.ph...0&postcount=41
http://forums.maxima.org/showthread....t=coil+testing

 

i tested the coil packs. all between 1.5 and 1.7 ohms. just to be sure i replaced the #5 pack (the one i tapped into). but the car is still not fixed. I rest the ecu and the same code has come back. Could I have fried my ECU?

 

Nope, I don't think you fried your ecu. Try moving the coil in quewstion to anotehr cylinder and see if it changes the miss (code, different cylinder)

 

would that do anything? I replaced the entire coil with a new one from autozone.

 

i just reset it the ecu and i still have the same 0201 code...its followed by and 0604 code.

 

It will shift the code and isolate the problem. If it's the coil itself, the code will shift/move to another cylinder, or if it's the circuit, the code will remain at that coil # regardless if it has a working coil pack or not.

 

so how do you fix a "circuit" does that mean that I have a bad wire to the coil pack?

 

I still think it's your CP. Your ECU would have fried, the car would be acting a lot weirder. I once wired in a SAFCII backward because I got the ECU front/rear mixed up (using a diagram, it's reversed, me = idiot) and even splicing into all the wrong wries etc, and tapping them and stuff, I didn't fry it, that's why I think your problem lies in the CP, not the ECU/etc.

I'll have to dig into the FSM to see what mechanism is used to fire the coils etc, and then go from there, but for now, I would still try and completely rule out the coil.

 

ok...i tested it. swaped the coils and the code stayed with the same cylinder - number 5.
obviously I messed the wiring up but I dont understand how. I didnt cut through the wire I only sliced back the insulation and soldered the tach wire to it. I have since un soldered this wire and wrapped tape back around it.

any ideas?

 

There are 3 wires to the coilpak; GND, 12V (from ignition) and the control gate from the ECU. That PU/W wire is the control gate wire for cylinder #5. The control gate wire is normally low (GND) and pulls up to 4V to drive the power transistor in the coilpak. The input terminal on the coilpak is normally high impedance. These are covered in the 1997 FSM on pages EC-9 and EC-92.

If you tap this PU/W wire with GND, then the ECU output driver (terminal #8, cyl#5) is toast after you start the car. If you tap this PU/W wire with 12V, you may get a spark with the key off.

 

I definatly tapped it with ground. does that mean I need to replace my ECU? or is the "driver" repairable?

i was hooking up the MSD RPM switch that when it reaches its set RPM it completes a ground. But what I tapped into it was the white tach wire that lets the MSD switch know what RPM it is.

 

I don't know what it looks like inside the ECU. If it is a discrete transistor, you may be able to replace it. But it may be in a chip or a multi-transistor pack. It would be a P-Channel MOSFET. The injectors use N-Channel MOSFET, pull to GND when active.

I am interested in your failed ECU if you decide to replace it. I picked up a 2nd ECU for my '94 Suburban just for backup.

 

i definatly dont know how to replace transistors. Ill PM you about the ECU.

 

If you are lucky, Nissan may have placed a fuse there. In that case just solder a wire across the blown fuse. There are close to 20 fuses in notebook computers.

Test that tap spot with a scope with the car running. A blown ECM control gate output would be at constant 4-5V. A working one would have spikes as shown in FSM page EC-92. If they placed a fuse and the fuse is blown then the line would be at GND.

 

what is a "scope"? I have a multimeter can I do it with that?

 

"Scope" is just short for oscilloscope. If the cyl#5 ignition output is blown, it will just read 4-5V on a multimeter. You can't read a working output on a multimeter.

 

Can I take the reading from the coil itself? the purple/white wire that runs to the ECU? if the car is running and all i have is 4-5v or GND then my ECU has either blown a fuse (if there is one in the ECU) or fried that port...correct?

 

If there is no fuse and the ECM output is blown, the line at the coilpak should be 4-5V with engine running. If they had a fuse in the ECM and the fuse is blown, it can either be GND or floating depending where they placed the fuse.

 

floating?? you mean that the voltage will randomly "float" up and down?

 

Yes, when it is open ended, then it can be anything. That output circuit should have a pull down resistor to fix it to GND when the circuit is not driving. If there is a fuse and the fuse is placed closer to the connector pin, then the pin will be floating after the fuse is blown.

So you can see if there is a fuse without opening the ECM. You can fix the ECM relatively easily if there is a fuse and the fuse is blown. So here is the three possible states:

1. Output high (4-5V), the ECM output is blown. Circuit is without fuse.
2. Output is GND, there is a fuse and the fuse is blown. Fuse is placed between the pull-down resistor and the driver.
3. Output floating, there is a fuse and the fuse is blown. Fuse is placed after the pull-down resistor and close to the connector.

 

ok....i got the new ECU today and put it in. Thats was not the problem.

I already know the answer to this but Im going to ask anyway. I tested continuity and it would not read tested from the plug on the coil pack to the ECU plug. Im guessing that when I tapped into this wire it fried that wire. Should I run a new purple/white wire from the ecu plug to the coil pack plug?

 

It sounds like you have eliminated the coil pack and the ECU as causes of your problem so you are accurate in suspecting the coil pack wiring. Here is what I would try, with the wiring at the ECU connected I would remove the connection from each coil pack. I believe there are three pins on the wiring side of the coil pack connector. Check the resistance to ground of each of the pins #1 #2 and #3 to ground. Do this with your suspect coil pack connector (#5) and also do this with the connectors for the wiring of some of the other coils. Make sure to attach the black lead of your meter to frame ground and use the red lead to probe the pins. If you have a problem with the wiring I would expect your readings for connections to the suspect coil pack to be significantly different from connections to the good coil packs.

Hope this helps to narrow the problem. If the resistance values at the suspect coil pack do not differ from the good packs then your problem may be somewhere else.

I would give you some resistance values and take a closer look but it's to damn cold here tonight.

 

If the PU/W wire is the control gate wire for cylinder #5, check the resistance value from that wire to ground in the manner I suggested above. Compare that reading to the gate control wires of the other coils. Again if you have a poroblem with #5 it should read significantly different then the other coils.

 

it does. the red wire (power) reads 12v and the black (ground) reads as it should. The purple/white while the car is idleing is at 0v while the same wire on other packs is fluctuating around 1.2-1.4v. I will check the resistance in the morning.

 

 

Your P/W wire should read zero Ohms (continuity) from the coil pack to the ECU. Compare resistance readings from the other coil packs to the ECU with the suspect coil pack. Comparing is a good way to confirm that what you are checking and the readings you are expecting are accurate.

Although not impossible it takes lots of current to fry the wire.

Are you sure you do not have spark at coil #5, even with new ECU and coil pack? FSM says you can to check by removing spark plug installing it in coilpack and cranking engine while placing sparkplug near a ground.

If P/W wire appears to be open, worth a try to change it but I would install a test wire (jumper wire) from the ECU to the coilpack before I made a permanent connection. Don't want to mess up the original wiring if possible.

I can not tell from the FSM if there are any fuses for these circuits in the ECU but I would not expext any. Check for fuses anyway, there would probably be 6 of them.

 

Normally it would not be that easy to fry a wire. Reviewing FSM pages EC-9, EC-92, EC-290-293; there were no fusible link either. If there is any fuse, it would be internal to the ECM.

Examine the connector and see if the #8 pin is ok or not. I would 2nd everything Nopike suggested too.

 

It cant be the ECM because it was doing the same on my old on and the new one i just installed. I swapped the coil pack from #5 to the #1 and the miss fire stayed with the #5 cylinder. I can unplug it and the car doesnt run any rougher.

the wire doesnt look burnt at all....so i dont think it is fried...but thats the only thing I could think of. especially since there are no fuses

I have looked at the plug itself and it seams to be fine. could it be anything else other than the plug or the ecm?

 

There can be a problem with the connection between the ECU and the coil pack but you need to perform the continuity checks I advised. I would still pull the plug and coil and make sure there is no spark to cylinder #5. Have you pulled and checked the condition of#5 spark plug? How do you know absolutely that that #5 cylinder is not firing?

 

Ok I tested the continuity. Here are the results:

#1 - 1.46 ohms
#3 - 1.56 ohms
#5 - 1.51 ohms

All of these are when the car is off and this rules out the coil packs as I have already determined when I swapped the packs from cylinder to cylinder and the none fireing cylinder stayed with #5

When I turn the car on...totally different results though:

#1 and #3 jumps between 0 to 10. - 14. ohms
#5 is at .00062 ohms

The volts when the car is idleing is this:
#1 - .11
#3 - .12
#5 - 0

Im going to try puting a jumper wire directly from the ECU to the coil pack and see if the readings change.

I also checked all of the fuses in the engine bay and under the dash. I couldnt think of where there could be any other fuses because that would explain why it has no voltage when the car is on.

 

its the wire. I ran a wire directly from the ECU pu/w wire to the injector wire. Car runs perfect and each cylinder reads the same voltage.

What I want to find out is where I cut the wire??? its obviously not making a connection. Any ideas?

 

That is good news, unfortunately you are not out of the woods yet.
If wire is burnt open most likely it would be near the coil or ECU connection. Strip off some of the insulation a few inches from the coil connection and jump a short lenght of wire to the coil.

Its still kind of weird becase a broken wire should read infinite resistance to ground and you don't appear to have that. It is possible that the P/W wire that you jumped out has shorted to ground or some other connection that would also cause problems.

Be careful using your meter to take readings with ECU powered up, you can damage it. I would stick to resistance readings without any power to the ECU.

You may consider having someone who has a basic knowledge of electrical circuits help you at this point. They should be able to diagnose this problem relatively easily.

 

The wire may have blown open near where you tapped it. Try to bypass that area.

 

so what are the chances of this happening?? I was testing everything with the multimeter today...tracking the purple white wire down through the wiring harness to narrow down where the break in the wire was...i found it. and i cant believe what ended up happening! I had to run a wire through the gromet in the firewall for the VI power from the RPM switch....when I did that I must have cut the Purple white wire with the tool I used to fish that wire.

What are the chances that out of all of those wires the one I would mess up is the same I tapped into????

Anyone need a 96 or 97 ECU? Ive got two good ones now..lol

 

Congratulations, tenacity pays.