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cs2000

No OBD2 Power

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Hey guys, seems like ive hit another issue. Ive created a new topic as I think this is a separate thing from my other (kind of solved) issue linked below

 

Following on from that long running saga, today I sprayed the MAF (gently) with electrical contact cleaner and also did the Crank Position sensor on Bank 1 (Drivers side), started the car up and went for a quick drive about. Once up to temp, I gave it some boot and the car kinda cut throttle, it stayed at whatever RPM it was at. Gently rolling into the throttle didn't cause the same issue, even with higher RPM's

 

I got home and connected my laptop and read code P0113 which is Intake Air Temperature Circuit High Input, the IAT in these is in the MAF sensor, so I figured maybe the contact cleaner hadn't flashed off before I started the car, cleared the codes and then my software disconnected, never to be seen again....

 

The only odd thing was I told the software to perform an Idle Air Relearn, this ran for 90 seconds and showed no sign of finishing, so I stopped it by closing the software.

 

I grabbed my generic OBD scanner which ive used on the car before and it didn't power up, seems I have no power at all to the plug!

 

Ive checked all 3 fuse compartments and pulled all fuses, none are blown. The ECU should be ok as the fans don't kick in when you turn ignition on (I disconnected it as a test and all the fans kicked in straight away which is a sign of a bad ECU)

 

The car now wont start either, despite me literally getting home, clearing codes and trying to start it, but that's likely due to some fault that I cant read right now!

 

Any idea how I can go about resolving the lack of OBD power?

 

As a temporary fix, could I take a 12v feed from the battery directly so I can connect the scanner and clear the codes which should let me start at least?

 

ive looked at the service manuals, it looks like the OBD port gets power from IPDM fuse 89, it looks ok but I changed it anyway and no difference still. The wires on the back of the OBD connector are well inserted and look ok too

 

Edited by cs2000

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IPDM fuse 89 feeds power to the OBD port pin 8 through the ignition switch.  This is Nissan-unique and not part of the OBD standard.  Direct battery power goes to pin 16 (OBD standard) through fuse 34 on the relay box located just in front of the battery.

 

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Right ok, so I have something else to check tomorrow/Tuesday.

 

i did swap IPDM fuse 89, so I’m suspecting fuse 34 now. I did pull that one earlier, but didn’t check it with a meter just visually.

 

another question then. Does power to the OBD connector ever go through the BCM? The reason for asking is I seem to keep getting  a P code (forget which number) which is the NATS system locking the car when it detects a bad key. I know the BCM has some say in this too as the BCM and ECU both talk during key verification.

 

im possibly thinking a bad BCM would be causing my intermittent key recognition failure and this new OBD lack of power issue.

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A bad BCM could cause your NATS problem, but pin 16 on the OBD connector goes straight to the battery through the fuse.

 

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Thanks mate, really appreciate your advice, il check when the time becomes available. Should be able to check continuity with my multimeter, could be a dead fuse or a damaged wire I guess, if its straight connected it cant be much else!

 

Failing that il wire something direct from the battery to the OBD plug to get me connected (removing the current power wire obviously, i dont know if it will like being back-fed with power)

 

I have also picked up a replacement good BCM from eBay for £30 of the exact same model. I was reading a TSB from Nissan this evening (doesn't apply to my car) but it confirms " The ECM and BCM do work together, but the BCM now controls the information necessary to tell the ECM to start the vehicle". With my seemingly random P1610 key lockouts, im betting on a failing BCM. Intermittent faults are the worst.

 

Once i have the OBD port working again, il swap the BCM, then perform the NATS key relearning procedure to add all the keys to the BCM/NATS system and i should (fingers, toes and everything else crossed) be off to the races.

Edited by cs2000

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P1610, Lock Mode, is a bit tricky.  It means you tried to start the car 5 or more consecutive times with either a bad key or a malfunctioning BCM or ECU.  Once the problem is corrected, you need to perform the following procedure to escape from the lock mode:

1. Turn ignition switch OFF.
2. Turn ignition switch ON with a registered key.  (Do not start the engine.)  Wait 5 seconds.
3. Return the key OFF.  Wait 5 seconds.
4. Repeat steps 2 and 3 twice (total of three cycles).
5. Start the engine.

This procedure comes from the US Service Manual, Body, Lock and Security System section.

 

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Yeah, thats kinda why i need the OBDII to be working again, i have had P1610 before and i know this software can reset the lock. 

 

I have 3 keys, including 2 remote keys and one dumb key direct from Nissan, i fail to believe that they've all gone bad in the space of a week as ive performed that reset and cannot escape NATS lockout.

 

The ECU/ECM must be good as i know if its disconnected/dead the rad fins spin up full speed when you turn the car to on, mine doesn't do that, so im almost set on a intermittent BCM, one is on the way :) This, along with hopefully a simple fuse swap should have me working again. Il keep you updated.

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@karlh was spot on, fuse number 34 inside the relay box (in front of the battery) was blown, Visually, it looks fine, however when checking with a Multimeter i showed a crazy high resistance, swapped it and got power to Pin 16 on the OBD plug. This let me go in and reset the ECU's learning, clear the NATS codes and the car fired up, however, the cut throttle is still there, revving up slowly is fine, using anything around 50%+ throttle causes the engine to bog and feel like a throttle cut.

 

I took some data logs of RPM, AFM Volts, Accelerator pedal Volts and Throttle position sensor.

 

Where the TPS sensors go up to 4v+, thats full throttle and as you can see, the RPM's fall off, then recover to 1200 RPM + when i let off the throttle.

 

Time, RPM, Air Flow V, Accel P1, TPS 1
000.078, 962, 1.38, 0.78, 0.66
000.156, 950, 1.38, 0.78, 0.66
000.203, 950, 1.38, 0.78, 0.66
000.265, 950, 1.38, 0.78, 0.66
000.328, 962, 1.38, 0.78, 0.66
000.406, 962, 1.38, 0.78, 0.66
000.468, 962, 1.38, 0.78, 0.66
000.531, 962, 1.38, 0.78, 0.66
000.593, 962, 1.38, 0.78, 0.66
000.687, 950, 1.39, 0.78, 0.66
000.750, 950, 1.39, 0.79, 0.66
000.828, 950, 1.38, 0.78, 0.66
000.875, 950, 1.38, 0.78, 0.66
000.953, 950, 1.38, 0.79, 0.66
001.062, 950, 1.4, 1.84, 0.67
001.187, 862, 2.92, 4.6, 4.13
001.265, 775, 2.35, 4.6, 4.13
001.343, 700, 1.94, 4.6, 4.12
001.421, 775, 2.62, 4.6, 4.12
001.500, 738, 2.98, 4.6, 4.12
001.593, 650, 2.18, 4.6, 4.12
001.687, 750, 2.27, 4.6, 4.13
001.750, 688, 2.3, 4.6, 4.12
001.828, 638, 2.41, 4.6, 4.13
001.890, 600, 1.82, 4.6, 4.12
001.968, 538, 1.79, 4.6, 4.12
002.062, 675, 2.56, 4.6, 4.12
002.140, 650, 2.46, 4.6, 4.12
002.250, 700, 2.68, 4.6, 4.12
002.328, 638, 1.91, 4.6, 4.12
002.390, 662, 1.95, 4.6, 4.13
002.484, 662, 2.46, 4.6, 4.12
002.562, 588, 1.8, 4.6, 4.12
002.640, 638, 2.34, 4.6, 4.13
002.703, 700, 2.67, 4.6, 4.13
002.765, 662, 2.09, 4.6, 4.13
002.875, 725, 1.94, 4.6, 4.12
002.984, 700, 2.52, 3.52, 4.06
003.078, 875, 1.62, 0.78, 0.88
003.171, 1125, 1.4, 0.78, 0.69
003.265, 1212, 1.48, 0.78, 0.69
003.359, 1188, 1.5, 0.78, 0.69
003.437, 1200, 1.52, 0.78, 0.69
003.546, 1262, 1.51, 0.78, 0.68
003.609, 1250, 1.52, 0.78, 0.68
003.703, 1262, 1.48, 0.78, 0.68
003.765, 1262, 1.5, 0.78, 0.68
003.859, 1275, 1.5, 0.78, 0.68

 

Im now (from the code i got the other day "P0113 which is Intake Air Temperature Circuit High Input" thinking i have a damaged MAF, maybe i sprayed the contact cleaner in a little too vigorously? The MAF may also have been hot from being recently ran, so spraying freezing cold contact cleaner may have just snapped one of the tiny heated wires.

 

From some further reading on exactly how important a MAF is

Quote

At wide open throttle, the fuel system goes into open-loop to provide maximum power. With a dirty MAF, the engine will run lean because of the under-reported airflow. Fuel trim will become more extremely positive but no code will set because of the (programmed) open-loop condition. Still, the engine will run so lean that it might not accelerate beyond a certain rpm, and this often leads to random misfire.

This is what im seeing! Im getting no CEL or ANY codes on ANY of the cars systems, but the RPM will not rise and it "feels" like a misfire.

 

I really should have taken logs of both long- and short-term fuel trims and the oxygen sensor. The fuel trims would show you if the ECU is compensating for inaccurate airflow measurement, and the oxygen sensor readings show you if that compensation is successful (which...it wont be!). During a full-throttle acceleration, the O2 sensor would normally report a rich A/F ratio, but it won’t if the MAF is dirty/broken/not reading for whatever reason.

 

Any thoughts on this one?

 

Still waiting for my new BCM to arrive to hopefully fix the NATS issue once and for all.

Edited by cs2000

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So interesting day. The BCM arrived, 1 day late, annoying but no biggie I guess.

 

Fitted it just now after checking all the fuses with a meter to ensure they’re good, pressed the lock button on the remote and oddly the car locked. Turned the key and there was no NATS led and the car fires up (was fully expecting to have to reprogram all of my keys). I did reprogram them anyway just as a safeguard.

 

started the car 5 times with each key and no startup issues at all. Weird I didn’t have to re-add the keys but hey-ho.

 

still waiting for a MAF to arrive to hopefully cure the throttle cut at high throttle input.

 

no further issues with lack of power on OBD which is good I guess. Seems to be getting there...

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Glad everything works.  I believe key registrations are contained in the ECU, not the BCM, and that the BCM is just a pass-through.  The Service Manual isn't very clear on the subject, but it does say re-registration is required after an ECU change, but says nothing about a BCM change.

 

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3 hours ago, karlh said:

Glad everything works.  I believe key registrations are contained in the ECU, not the BCM, and that the BCM is just a pass-through.  The Service Manual isn't very clear on the subject, but it does say re-registration is required after an ECU change, but says nothing about a BCM change.

 

Interesting indeed. From my reading, I took away that the BCM actually stored the registered keys, but I’ve been proven wrong, the wording as rather vague, I’m just hoping this resolves the startup issues longer term. 

 

The TSB I read said “The ECM and BCM do work together, but the BCM now controls the information necessary to tell the ECM to start the vehicle", I guess that’s open to interpretation of course! Even a BCM replacement guide on the US forums tell you go tow the car to Nissan once you fit the BCM to have it programmed.

 

if this doesn’t work, next thing il be looking at is the NATS antenna around the ignition barrel. However I don’t think (but not sure) that my software can pair this to an ECU which would be required as far as I know, so fingers crossed I don’t have to do that as il have to buy an ECU and NATS antenna from the same car, that also means losing my UpRev tune.

 

Further testing continues once the MAF arrives.

 

Thabks again @karlh, I’ve not seen your name much on these forums, but you’ve been very very helpful!

Edited by cs2000

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MAF arrived today, fitted and actually works which is good I guess!

 

Anyway, performed the Throttle Pedal & Throttle Body Position Reset pedal dance's, couldn't do the Idle Air Volume as the car wasn't warmed up (which is required).

 

however, on +50% throttle it still throttle cuts, which is weird. No CEL, no errors stored in any of the cars systems. very odd.

 

Ran out of time today, its the time of the day when the school mums come and clog up the roads, so I cant go for a drive, but next steps are another ECU Learning Reset, then to try an idle air volume learn after warming the car up.

 

Il also remove the intake tube, check the throttle body is free of debris and re-seat the entire intake tube and filter, but after that im out of ideas!

 

This all happened after disconnecting and cleaning the MAF and Crankshaft Bank 1 sensor plugs, no other symptoms. Car is absolutely fine I driven at any speed and any RPM's as long as I don't exceed around 50% throttle.

 

Any other clues what to check failing this?

Edited by cs2000

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Welllll, I feel like an idiot....

 

So as I said, ran out of time earlier to test, all I knew was throttle cut was still happening. Next steps were to get the car warm, perform Idle Air Volume Learn and then remove the intake tube, check the throttle body is free of debris and re-seat the entire intake tube and filter.

 

The wife is staying away this evening and I couldn't rest on the car, so I decided, well its dark now, roads are quiet, lets go get her warmed up. Got her nice and warm and put my foot down, throttle cut :rant:but out the corner of my eye, I noticed something. My WOT box (Launch Control and No Lift Shift controller) was blinking as though it thought I was trying to No Lift Shift. so I pulled over, connect up my laptop and took a look.

 

As it turns out. During my meddling with the no start issue, I had updated the firmware of the box, and what does this do? Well it resets all your settings! SO what did that mean? It was trying to read my engine as some kind of Dodge engine, no biggie really, but the kicker was the Clutch position sensor was reading backwards so it ALWAYS thought I had the clutch down when it was up.

 

If I was using over 50% throttle (the threshold for no lift shift to activate) the WOT box assumed I wanted to shift. Because the clutch was being read wrong it assumed I had it held down and duly cut ignition so I could shift !!!!!!!

 

A quick selection box change in the software was all that was required to fix the "odd" throttle cut (which was actually spark cut as it turns out...)

 

FML, I feel like a right lemon. Plus points, my MAF was fine. Anyone wanna buy a brand new MAF used for 15 miles? :p

 

I did get a error code during my drive of "P0340 CMP SEN/CIRC-B1" so perhaps I do actually need a bank 1 camshaft sensor, but I cleared it, drove some more miles and it didn't return, but at least if that's what I do need eventually, I know its an easy swap, just don't buy eBay cam or crank sensors, they 100% do not work.

Edited by cs2000
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