Folks,

Testing out a new toy here, and ran across some strangeness.

I've got a 730 and an old 749 ECU that are both showing a constant 450mV (120 raw integer) for the O2 input on the datastream. I bring WBO2 0-5 in on DIAG2 (B7 I think it is) via simple code patch through FP voltage slot in the ADS.

Perhaps a little help here so I'm not losing my mind. Here's my assumptions.

For the 730 running $8D, I even tried a virgin AUJP file, the O2 should be on byte 17 of the packet. Still happens. Other data (RPM etc) come through clean and as expected.

The O2(Hi) is on E14 and that's where the voltage should be coming in. In my case, it's a simulated NB from the WB. The O2(Lo) is on E15, and should be grounded. If E15 floats, it shows around 1.5v or so.

I can sit there and measure the volts at pin E15 at around 100mV off of GND, but the ECU data shows constant 450. At first I thought I'd butchered up a code segment in the $8D, but no, untouched file does it also.

I'm going to grab another ECU today and see what happens. I just thought it was odd that both of the ECUs I have see this issue.

Many thanks,
Craig

 

Silly question, I know... But you did verify that the input was changing or at least not 450mV at the input, correct?

I take it this was in car testing, not on a test bench?

It sounds like the ECM is not seeing an input, IIRC, with no connection to the NBO2 input it will default to 450mV.

If you're testing what I think you're testing, let me know as soon as I can get my hands on a beta unit to test in my car.

 

Interesting, and I'm surprised this hasn't come up before, or maybe it has.

The NBO2 input seems to be locked in at that value, regardless of the actual input to the ECU pin, IF the motor isn't running. When you're in a running condition, it updates just fine to the ALDL.

No ECU problems, guess it's like a FW-based 'dummy' light for the ROM code.

 

Hmm.

I honestly hadn't noticed that chain of events. I will have to do some observing on my test bench.

 

This is true. The O2 values are initialized to 450 mV at key-on, engine-off. And some code bases continue to init the O2 value until the engine is running.

RBob.