mgk5391

Working on my 03 350z I have been experiencing issues with flashing stock ECU. Every attempt gives me Can Bus error. I've research the issue but there seems to be very little information on resolving it. So I'm making this thread to try to pin point things to check to hopefully solve my problems and help others out.

Things I tried so far:

1. Using multimeter I check the voltages and Resistance on the diagnostic port harness. Mainly pins 6 and 14.
pin 6- CAN high
pin 14- CAN Low
Everything came out fine for both test.
(If needed I can provide details on how to test.)

2. Researching in forums I found one member on here had the same issue and it turned out to be a faulty cable. Not sure if there's a way to test cable yet but will venture this avenue.

Update: I tried flashing with newly purchase cable (as Seymore4 suggested).
Still have the same issues, so I don't believe this is the problem.

3. I spoke to UPREV and I was recommend to check aftermarket radio is not interfering with flashing. Or directly wire to ECU for best connection. Overall, any electrical interference should be eliminated.
So I'm working on removing the radio and checking wires.

Update: So I went ahead and removed the aftermarket radio and adapter harnesses and I'm
Still experiencing the same issue. I'm not 100% sure (I may have do more research) but I think this isn't my issue either.

4. Last, I notice that my connecter is having a hard time finding the ECU. Only after changing the angle that the interface attaches to the diagnostic Port (after ~ 5-10 mins) it finally picks up the ECU. Connecting the interface on a friend's newer Infiniti it immediately connects, no problem at all.

I believe the pins in the diagnostic port could have been damaged or bent causing this issue.
I'll try direct connection with all pins and report what happens.

So overall, these are things I've checked or will be testing. Has anyone else experience this issue or found a different solution?

seymore4

iTrader: (27)

If you have the newer 2 piece cable then try a different USB cord. They are generic and can be swapped around, I've seen them defective before and they will give you all kinds of errors

mgk5391

Thanks! I tried this today and still having the same error, so not the cable. I'm zeroing in on what I believe to be the problem though. I'll update my main post.

seymore4

iTrader: (27)

If you have access to another Z/G you might try and flash that one just to rule out a defective cable. If it works then flash it back to stock and you know its your car and not the cable/ software

mgk5391

I thought the same but didn't have another Nissan to try at them moment. If my friend with the infinity is okay with it, then I'll try this weekend.

Update:

I found two things since last weekend.

1. My UPREV cable is completely fine. I was able to flash my buddy's Infiniti once and back to stock.
So no problem there.

2. Poking around the engine bay, I found that two fuses were blown that directly related to engine control.
They are labeled "Eng Cont" and both are located in the two fuse boxes next to the car battery.

One was linked directly to the 12V+ pin in the diagnostic port. I blew the fuse while testing pins I removed from the J1962 harness.

The other, I'm not sure what it controlled but it seemed to be linked to Can Bus wires per wiring diagram from Nissan Service Manual. I'll try to flash again this weekend to confirm if it fixed my issue.

mgk5391

Problem solved!

I believe I had two problems. The blown fuse prevented Rom Editor from finding the ECU. Also, the Diagnostic Harness (J1962) was damaged and caused a weak connection between my Uprev Dongle and ECU. Connecting the pins directly to Uprev Dongle allowed me to flash the car. Working on replacing the harness now

Hope this helps anyone, that has similar issues.

BluestreamDE

Good info here, thanks for sharing your discovery.

Italianjoe1

iTrader: (6)

I've seen the pins get bent in ODB2 connectors on scanners and such, but generally if they get straightened out they work just fine.