Ok well here is the scoop. A few months ago my SES light came on with codes 0325 (knock sensor) and 0420 (cat/02). I figured that with 110K miles the KS must be shot. So I replace the KS, all the wiring, and the harness. P.S. The KS we pulled was brand new. I cleared the 0420 code but the KS code remains present. Last weekend Kevin (KRRZ350) put in a resistor from the KS to the ECU and upon completion, tried to reset the code with his OBD-II scanner. My car froze the machine and was unable to access the vehicle information. It worked on other cars he had but not mine.

Two nights ago, I was going to autozone to get some misc. stuff when the SES light decided to come back on. 0420/0325 still. They couldnt clear the codes either so I decided to leave the battery disconnected overnight in order to clear the codes and reset the ecu. 14 hours later right after reconnecting the batt. the SES light is right there. So obviously the ECU was unable to reset.

I will be going away for the weekend (Fri-Sun) and plan on leaving the batt. disconnected for those 3 days in HOPES that the ECU can reset itself and I can finally loose the code. I believe these codes are related, even though I can care less about the 0420 because I think it is just from having my car run rich (retarded timing).

If leaving the batt. disconnected does not do anything and the ECU does not reset, anyone have any other backup plans other than brining it to Nissan and spending the $100 to tell me what is wrong/reseting the ECU (which prob wont). I seriosuly just want my timing back. I hate getting smoked at traffic lights...and the loss of torque is getting really noticeable.

 

Use the screw method(yes 99's can do it too, just need a small philips). Disconnecting the batt won't do anything.

 

I know, I just tried again. The SES light was just on and it cleared the 0420 code but not the 0304. The light is now off because I cleared the cat/02 code but the KS code still remains present.

 

Did you over tighten the sensor?

 

your fault and reason why CEL is because of 0420. which is a cat fault. A cat fault on other cars i've seen would randomly trigger. it would be on and off and never a constant on. i didn't read up that you did fix this fault.

in theory your KS should be gone but your CEL will still be there because you never fixed the 2nd fault if you cleared all faults. but you have the exact oppisite. Now you said " you pulled a brand new KS " what that mean? you bought one brand new or you took one off a car ? I just think you got a bad sensor because the resistor trick has had a VERY VERY low sucess rate none the less. i would say if you got a new sensor to warranty exchange it or if you got a used one to go out and BUY a new one.

disconnecting your battery will never do anything except for reset your clock and preset radio stations.

 

Ok here is what I did. When I said "I pulled a brand new KS" I meant that the KS I pulled out of the car was perfectly fine. I bought and had a BRAND NEW knock sensor put in and took the "like new" knock sensor out and sold it to someone on the .org. It was in perfect working order and tested about 540 ohms...which is completely normal. We also replaced the wiring harness and wiring. THE KS WAS TORQUED PROPERLY also.

The 0420 code I can care less about because it is random and will clear whenever I tell it to. I have tried clearing ALL codes by using an OBD-II scanner and by the screw method and neither will clear the KS. Even when the KS is there by itself, it will not reset. I again am NOT worried about the 0420 because it is a whole different issue that is not at the top of my priority list. With a KS code my timing is shot to hell under 3000 rpms and it is so bad that I thought my clutch was slipping.

 

There's one of two things going on here, and next to swapping out another ecu, I'm 'almost' at a loss as to the next steps, more on that in a second. For starters, the problem is not with the knock-sensor or knock-sensor circuit, when removing the ecm harness from the ecu and probing the female terminal #64 & ground, there is 460k ohms, so there should be no knock sensor code present. A visual inspection of the female terminal indicates that it is ok, nevertheless I tried applying slight pressure on it while attempting to erase the code with my scanner, still no go. Now, on to erasing the code... When I go to 'erase all codes' with my scanner it gives a message along the lines of 'communicating information blah blah blah' then afterwards it says 'information was sent to the vehicle', yet the ks code will still be present right away, It's been a little while and I am going to do a test on another vehicle when it stops pouring, but I could have sworn that when my scanner erased codes it would say 'all codes cleared' or something along those lines. Now, here's where it get's odd and why I think there is a weird glitch with his ecu, when selecting 'vehicle information' with my scanner it comes back with a message stating 'unable to communicate with vehicle', yet when I perform this same procedure on either of my cars ('96 & '04) it spits out a bunch of useless can #'s and id code's etc etc.

After talking with Nismology the other night I feel a little on the stupid side, I never even thought to backprobe the ecu connector and check the reference voltage at pin #64, HOWEVER, I feel that even if I do this, what good does that really do me to narrow down this problem? It doesn't, anyways, matt please don't bother taking it to the dealer, they will begin to make all of the same checks I have and charge you up the ***. I know you want you're timing back, but please wait for Zach to get back to me regarding his spare '99 5mt cali-spec ecu.

Anyone's thoughts now with the new information are welcomed........

 

I still think checking the reference voltage holds some value. I feel that Nissan posted a voltage specification there for a reason. If the voltage is off, then perhaps something is going on inside the ECU.

I do agree, though, that he shouldn't do anything hasty until you try a different ECU.

 

Oo Im glad to hear that someone local has a spare 99 5spd cali ECU that hopefully we can test. I went to autozone a few hours ago, and their OBD-II scanner was able to send a command to the ECU to clear the codes. Now, I doubt it cleared them but we shall see. I am most likely going to the meet next thurs. so hopefully we can figure out what the hell is going on there.

 

Now the only reason why I said maybe I should bring it to Nissan is because another local member told me that he has access to a Nissan Consult Diagonostics Computer and I think he could prob get me a reduced price on it. I only plan on doing this if we cannot conclude anything after swapping ecu's. (if we indeed can swap the ecu's).

 

The thing about swapping ECU's is that since you have a '99 the car won't start until the "new" ECU is programmed with your immobilizer info so you'll have to go to the dealer either way.

 

I know older 4th gens had issues with broken wires in the harness near the pass side strut tower ...

 

Good to know, but not the problem in this case.

****, I totally forgot about the immoblizer, that totally fuxors everything, I don't know what to say here now. I'll bring my multimeter and scanner to the meet.

 

Hmm....what if I could "borrow" Zach's ECU? Anyone know of a way to contact Zack342 directly? I will send him a PM right now but I need to get a way to fix this sucker.