Not your average p0157. Please help.

Don't mean to hi-jack an old thread, but I am having a very similar issue with a P0157 code popping up. Per my ultra gauge I'm getting 0v out of B2S2, already swapped O2 sensors with Bank 1 and problem stayed in the Bank 2. Which leads me to believe it's a wiring issue. I'll start by checking voltage at the connector and see what I find out.

I was just curious, would it hurt the ECM or anything else on the truck if I apply 12v directly to the connector, or do I need to reduce the voltage somehow? Trying to mimic step #4 and read voltage on my ultragauge.

Also does anybody know the wiring route to the ECM? my next step was to check wiring condition and continuity to the ECM connector terminals.

No Engine or ECM swaps on mine, however I am running a UCON EMS Piggy Back with no cats.

What scanner are you guys using to record the waveforms?

Thanks in advance,
Fed

 

Use a test light connected to battery positive, don't use a jumper wire.

Would help to know what year and engine you have to provide the correct diagrams.

 

Sorry about that have a 2007 tacoma 4.0 v6.

 

Here's the relevant diagrams.

Pins on the sensor connector are as follows:

Pin 1 (Blue): Heater Control (PWM Ground from PCM (E5 Pin 5))
Pin 2 (Blue/White): Heater Power (Battery Voltage with key on)
Pin 3 (Black): Sense Circuit to PCM (E5 Pin 33) (0-1v depending on sensor output)
Pin 4 (Brown): Sensor Ground (Ground at all times)

 

Would I be able to accomplish the same with a multimeter?

 

You wouldn't be able to do a bypass test with a meter, essentially we're wanting to send power to the signal wire and look for the voltage to change on the scan tool. A test light is the safest way, worst case if your on the wrong wire or the wire is shorted the test light lights up. With a jumper you risk letting the smoke out of something if your in the wrong terminal or there's a short.

A bypass test tells us several things, that the circuit is intact & not shorted and that the ECM can see the signal.


You said you were running a piggyback and no cats, what exactly is that doing?

 

Toyota wasn’t able to tune my ECU after I supercharged my truck, the UCON was my only option at the time.

Ever since I removed cats, added a 7th injector and a smaller pulley.

 

But what is it doing with the downstream O2 signals? It must be doing something to prevent the ECM from throwing a P0420/430.

I didn't think 7th injector was a thing on 2nd gens, most people do a custom tune.

 

I don’t have details since it was tuned out by URD.

I do know there was no need for o2 simulators since UCON took care of that.

Maybe I need to reach out to URD

 

I can't help you there, I know how the stock system operates but having that in between complicates things.