possible bad rear o2 input on ecu

[Fast95GSX]

I am having a problem logging my aem uego. I have it wired up to the rear o2 and measured the voltage coming out of the white wire from the gauge. With the o2 sensor disconnected the voltage is 2.39. With the o2 connected it's 3.83 volts. Now trying to log the wideband the voltage is always stuck at 1.61 volts.

I check the white wire to pin 75 on the ecu and made sure it was solid and it was. Where do I go from here?

 

[Fast95GSX]

Nobody has any ideas to the problem?

 

[eclipsegsx1736]

The AEM UEGO WB will always default to 14.7/14.8 when the O2 sensor harness is unplugged from the gauge.

Are you using DSMLink to log? Are you sure you do not have anything else hooked into pin 75, including possibly the OEM rear O2? Try cutting the wire on the harness side, and running the white wire from the UEGO directly into the ECU's input.

 

[Fast95GSX]

The AEM UEGO WB will always default to 14.7/14.8 when the O2 sensor harness is unplugged from the gauge.

Are you using DSMLink to log? Are you sure you do not have anything else hooked into pin 75, including possibly the OEM rear O2? Try cutting the wire on the harness side, and running the white wire from the UEGO directly into the ECU's input.

I ended up wiring it into pin 73 MDP input and it works like a charm now. I'm glad I can now log my wideband but it still makes me wonder why pin 75 rear o2 wouldn't work correctly.

 

[eclipsegsx1736]

The rear O2 and MDP have different pull-down resistor values (220k down for rear O2 vs. 100k down for MDP) but I've successfully used both inputs with a UEGO on my daily that has DSMLink. I'd still bet that there's something else on that circuit pulling the voltage down.

Beau

 

[Fast95GSX]

I'd still bet that there's something else on that circuit pulling the voltage down.

Nothing else is wired to that input though. Could it be that maybe I don't have a grounding strap on the downpipe?

 

[snowborder714]

Are you positive you got pin 75 and not pin 76? They're both white wires, and right next to each other.

 

[Fast95GSX]

Positive on pin 75. Dave from ecmtuning suggested that I had the stock rear o2 but it has a 6 pin connector.