16197427 PCM with no O2 sensor reading

[FSJ Guy]

I am running a 16197427 PCM on an AMC 360 V8 engine. This is my 3rd TBI conversion, second '7427 conversion but it's been several years. I am running a modified $0D code. All the other sensors read correctly, so I feel that I have the correct XDF and acquisition files in TunerPro.

I am running a Bosch 4 wire O2 sensor. I have double checked the heater wiring as well as the sensor wiring. They appear correct. The heater circuit on the sensor measures about 5 ohms and when I probe the O2 sensor with the engine running, I get aprox 0.100 volts, I think the sensor is good. It better be. I purchased a new one.

But when everything is hooked up, wit the engine running, TunerPro shows aprox 0.440 volts. and it NEVER moves.

That tells me it is not reading the sensor. The other thing that tells me the sensor is not being read is that ALL my BLM #s are 128. And I KNOW that is wrong.

Any idea on where to start?? I swapped PCMs and there was no change. The swapped PCM read a constant 0.453 volts.

TIA!

[Six_Shooter]

Are you sure the O2 input wire is in the correct pin to the PCM?

[FSJ Guy]

Are you sure the O2 input wire is in the correct pin to the PCM?

Yes. I unplugged the sensor and checked continuity from the plug to the PCM connector.

It was cold out yesterday so I will try again tomorrow. But I did wait until the engine was up to normal operating temp. I will try to drive it a little, too.

If if all else fails, I can try swapping sensor input and ground.

[FSJ Guy]

Problem solved:

I mistakenly wired the Sensor Ground back to the PCM instead of to an actual GROUND. This was discovered by metering the two grounds. The potential should have been zero, but instead was ~2 volts. I checked the schematics and realized my mistake.

Once I grounded that wire (leaving it connected to the PCM), the O2 sensor started reporting and all is well.