Tungsten Posted September 23, 2011 Share Posted September 23, 2011 See this thread: http://www.nissanpathfinders.net/forum/index.php?showtopic=31278 Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 24, 2011 Author Share Posted September 24, 2011 Grounded Pin B on connector and wire to a new spot, spliced together and erased the codes, to find it flashes like this now...: http://www.youtube.com/watch?v=vPYV-b1th1s Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 24, 2011 Author Share Posted September 24, 2011 (edited) nevermind that..apparently that was a diagnostic mode..heh. Edited September 24, 2011 by NissanNismoZ Link to comment Share on other sites More sharing options...
Tungsten Posted September 24, 2011 Share Posted September 24, 2011 If you are reading 0.7v at the ECU pin 16 and 1.58v at the sensor on pin C then there is your problem. Link to comment Share on other sites More sharing options...
Tungsten Posted September 24, 2011 Share Posted September 24, 2011 Ok, so here's the thing where you lose me. If pin B is grounded, shouldn't pin 17 on the ECU also be at ground? Are you serious? Did you not see my previous posts? They are specifying that it is a ground circuit in the FSM! Nissan even released a harness that adds an additional ground to pin B. Here is a picture for you in case you missed it: LOOK AT IT CAREFULLY!!! Now as to why pin 17 has voltage I guess it all depends on how you measure it. Link to comment Share on other sites More sharing options...
sewebster Posted September 24, 2011 Share Posted September 24, 2011 LOOK AT IT CAREFULLY!!! Now as to why pin 17 has voltage I guess it all depends on how you measure it. Admittedly I did not notice the words "check ground circuit" before, heh. It still seems to me that if you measure voltage between pin 17 on the ecu and ground with the ignition on that you should get 0V or very close to it. The fact that he is reading a voltage there which is significantly above (or below) zero seems to be bad to me. Unless the FSM has referenced their ground to -12V or whatever, which would be confusing. Anyway, as we have both mentioned, he is clearly not getting the correct signal at terminal 16 on the ecu, so that needs to be fixed. Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 24, 2011 Author Share Posted September 24, 2011 If you are reading 0.7v at the ECU pin 16 and 1.58v at the sensor on pin C then there is your problem. Admittedly I did not notice the words "check ground circuit" before, heh. It still seems to me that if you measure voltage between pin 17 on the ecu and ground with the ignition on that you should get 0V or very close to it. The fact that he is reading a voltage there which is significantly above (or below) zero seems to be bad to me. Unless the FSM has referenced their ground to -12V or whatever, which would be confusing. Anyway, as we have both mentioned, he is clearly not getting the correct signal at terminal 16 on the ecu, so that needs to be fixed. both correct! So i'm going to try and remedy this problem by changing harnesses completely. Thanks guys!! its appreciated! Link to comment Share on other sites More sharing options...
Tungsten Posted September 24, 2011 Share Posted September 24, 2011 So I just realized how in hell is it reading -12v or 12v with another ground and I started to question that pin 17 myself and see if I have any voltage in it. I checked and there is not any voltage there. I am thinking his ECU is doing something funny or there is a short circuit somewhere in that wiring. Thing is you can actually reduce voltage to a circuit if you hook both positive and negative wires to voltage sources. Let me give you an example... Suppose you have a 12v fan. If you plug the positive end into +12v and the negative end into +5v then the +5v becomes -5v and the 5 subtracts from the 12 and you get a fan that only runs off +7v. This can be done to regulate the voltage to the fan and reduce noise. If you subtract more than 12v then the electric current will go the OTHER way and make the fan spin the other way or destroy it depending on how it is designed. I was thinking that if you have +12v to the sensor on one side and some other voltage on the other then you could regulate the voltage to the sensor. However that does not make sense because there is only one common ground that goes off the sensor. So by regulating voltage to the sensor you would also interfere with the signal sent from the sensor and throw off the ECU. So it is confirmed that the voltage regulator and heater for the MAF sensor is built into the sensor. As to why the pin 17 is not actually a ground I think there is a chip in the ECU that has to sense 0v on pin 17 vs 1.58v on pin 16 to ensure a correct reading and that the sensor DOES NOT have a short circuit in it or some other crap. Therefore, grounding B does absolutely nothing to the ECU but if something abnormal happened to the sensor the ECU will not pick that up and instead the fault will just blow the ECCS fuse. Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 25, 2011 Author Share Posted September 25, 2011 So! Today i was told to check for a electrical leak..so i did by checking for volts. -.44v = Top of my radiator +.18v = Top radiator hose clam +.18v +.20v = Other side of radiator hose clamp (closest to engine) +.21v = Fuel line clamp under the intake, under the two grounds, (refer to previous posts to see picture) I'm out of places to probe.. any ideas?? BTW when i check for ohms on the intake, it goes into the negatives, -.19 ohms resistance...? Link to comment Share on other sites More sharing options...
Tungsten Posted September 25, 2011 Share Posted September 25, 2011 Basically what happens is the ECU has a ground leak monitor and it compensates the reading to all the sensors which is why you can still drive around with codes for so many sensors. Therefore I think there is a ground leak and possibly close to the fuel line clamp. Why not pull some fuses and test until the voltage in that area disappears? Then you can check the wiring diagram to see what the things are you can check in that chain. 1 Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 27, 2011 Author Share Posted September 27, 2011 I pulled all my fuses individually and nothing changed..hmm.. Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 28, 2011 Author Share Posted September 28, 2011 So..i've exhausted all possibilities.. FSM is of no help in this situation..does anyone else have any other ideas? Most of what i've done is...: Replaced MAF harness and connector. Replaced MAF Sensor Replaced ECU Added several grounds Tested in every single way we could think possible. Any more ideas? I'm the stubborn type and its really aggravating to me that i cant figure out something.. So of course, i'm about to take it to a shop and have them fix it.. i'm completely lost now. Link to comment Share on other sites More sharing options...
sewebster Posted September 28, 2011 Share Posted September 28, 2011 Are you getting the correct voltage at pin 16 on the ECU now? Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 28, 2011 Author Share Posted September 28, 2011 (edited) Are you getting the correct voltage at pin 16 on the ECU now? Nope, MAF is sending out 2.15v and the computer is receiving .59v ..could that be a prblem ir is there some sort of step-down somewhere? Edited September 28, 2011 by NissanNismoZ Link to comment Share on other sites More sharing options...
adamzan Posted September 28, 2011 Share Posted September 28, 2011 Cody, maybe I can check my pin 16 and see if it is the same, if it is that would rule out another item. Link to comment Share on other sites More sharing options...
sewebster Posted September 28, 2011 Share Posted September 28, 2011 Nope, MAF is sending out 2.15v and the computer is receiving .59v ..could that be a prblem ir is there some sort of step-down somewhere? That is a problem. The FSM gives the range of acceptable voltages at pin 16 and 0.59V is not in it. Sounds like you have a wiring problem between your MAF and ECU to me... Unless there is a typo in the FSM or something. I guess Adamzan can double check for you. Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 28, 2011 Author Share Posted September 28, 2011 okay, so my shop teacher told me to run new wires to the ECU from the maf and see if that helps..just done it and will reply when i can test it. Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 29, 2011 Author Share Posted September 29, 2011 OK so i know that im wiring it correctly..but.. im wiring B to 17 and C to 16..straight from the MAF and..its running kinda bad now, i cant get any voltage signal from the maf at all, but its still getting the power supply..whats going on?? i dont understand what im doing wrong... Link to comment Share on other sites More sharing options...
Kingman Posted September 29, 2011 Share Posted September 29, 2011 (edited) So! Today i was told to check for a electrical leak..so i did by checking for volts. -.44v = Top of my radiator +.18v = Top radiator hose clam +.18v +.20v = Other side of radiator hose clamp (closest to engine) +.21v = Fuel line clamp under the intake, under the two grounds, (refer to previous posts to see picture) I'm out of places to probe.. any ideas?? BTW when i check for ohms on the intake, it goes into the negatives, -.19 ohms resistance...? The " - " usually means you have the test leads backwards. okay, so my shop teacher told me to run new wires to the ECU from the maf and see if that helps..just done it and will reply when i can test it. If you do this, either keep the factory shielded reference wire or buy another one new. Do not leave out the shielding, it's definitely there for a reason. Edited September 29, 2011 by Kingman Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 29, 2011 Author Share Posted September 29, 2011 reference..you mean the power to the MAF? i left that wire alone, i only ran new wires to B and C on the MAF..which are pins 16 and 17 on the ECU Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 29, 2011 Author Share Posted September 29, 2011 Okay..so..i gave up (until i can get an idea from someone) and rewired it to stock wiring.. Link to comment Share on other sites More sharing options...
sewebster Posted September 29, 2011 Share Posted September 29, 2011 Those wires are supposed to be encased in a grounded metal shielding I believe, that is what Kingman is talking about. Are you getting the proper voltage at pin 16 with your new wiring? Sounds like you aren't, so something is still wrong... Link to comment Share on other sites More sharing options...
NissanNismoZ Posted September 29, 2011 Author Share Posted September 29, 2011 (edited) After wiring it up straight to teh ECU, i get the proper voltage IN (Pin A is left alone, it reads battery voltage) but..its not sending anything out, which makes me suspicious about pin B so i tried replacing one wire at a time..so.. i left pin C stock and B new wiring..no change. i leave pin B stock and pin C with new wiring..and..pathy runs at 200-300rpm, shuddering horribly? O.o Edited September 29, 2011 by NissanNismoZ Link to comment Share on other sites More sharing options...
sewebster Posted September 29, 2011 Share Posted September 29, 2011 It might help to have the voltages at the MAF harness and ECU side in the different configurations, but it sounds a little weird. Basically by fixing your wiring your problem gets worse, not better. Not sure what to suggest. You need to thoroughly determine that your MAF is wired properly, with the auxilliary ground, with shielded wiring etc, and that the proper signal is getting to the ECU. Then you can try comparing all the readings etc. between your different wiring setups to try to see what is going on I guess. Link to comment Share on other sites More sharing options...
Tungsten Posted September 29, 2011 Share Posted September 29, 2011 There is no reason why the problem should be worse with new wiring unless the new wiring sucks. There is most likely some kind of an electrical issue that's interfering with everything else. Link to comment Share on other sites More sharing options...
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