2001 Dodge Dakota 5.9 Automatic 4x4--Bank 2 sensor 2 slow response.

My shop had been trying to fix this truck for several months before i started. Previous tech replaced all o2 sensors with NTK brand. It has had transmission replaced. Previous tech also DID find some harness damage from trans install. Tech has passed away so can't ask any questions. The Bank 2 sensor 2 goes to zero volts about 30 seconds after start-up. Stays at zero. When viewing data cold, 3 sensors show 4.98v, BK 2-2 shows 3.07. Do i have a harness short to ground? I'll recheck tomorrow with all sensors disconnected, then reconnected one at a time. Try to get some Verus scope readings. I wrongly assumed the 3.07 indicated a PCM issue. After watching some of your Mopar videos on bias voltage I realize i probably have a short to ground on signal wire. Also didn't realize even connecting to circuit would change voltage reading.

It might be worth doing a simple unplugged resistance check (both cold and warm) on the sensor heater and comparing it with the other sensors. With the plug disconnected you could also try substituting a tungsten test light for the heater.

Measuring the voltage with a multimeter on high current circuit such as a sensor heater won't pull the voltage down by any noticeable amount . Reasonable quality Multimeters (and Oscilloscopes) have very high input resistance on the voltage scale. However some voltage probe type tools have a lower input ressistance (300 k ohms) with can pull the voltage down on sensor outputs but are still OK for high current circuits such as O2 sensor heaters and lights.

My code is for O2 signal circuit NOT heater. Why would bias voltage be different to one sensor?

Aw, that's sad to hear about the previous tech. For our info, what was the P-code?

The 3V bias makes me think of a resistive short. I can recall running into a similar issue when water got accidentally sprayed into the harness side of the O2 connector. It wasn't a dead short, but it was shorted enough to pull the bias down and take the O2 signal with it. Possible weak/missing weatherpack seal?

Ohming wires sucks, but this might be a good occasion. PCM and O2 disconnected, see if there's a reading to ground. You can also try cutting the O2 signal wire close to the PCM (where it'll be repairable, of course) and see if the bias goes to normal.

Added code to title. P0159. These are 5 volt bias. I did ohm wires from o2 end to PCM connector but really need to start over. Think cutting the circuit loose is my next step. The harness definitely has trans fluid intrusion from range switch.

Some readings and where I assume the hard shell of connector was changed. I had it reading 4.96 volts (cold) until harness was back in place. Then back to shorted reading. The voltage changes really quick when sensors are heated. This damn thing has one, big, engine/transmission harness. Makes it hard to get it out to work on. Think boss is going to ship it to local electrical shop. All four read basically same voltage until an o2 sensor is connected to 02-2. Cold sensor should have ZERO effect since "sensor" side is basically open when cold. Return circuit has to be shorted to ground of heater IMO.

Don't mean to cut in here but could the pins be in the wrong place in the 2-2 connector? Or possibly the wrong sensor ? Is this a 3 or 4 wire sensor?

Sent from my SM-N920P using Tapatalk

I think they were in the wrong place. I pulled all the pins and re-did it. Only problem was, at the time, couldn't find the connector view. Just found it a few minutes ago. Pin 1&2 (latch side/upper part) are heater/3-4 sensor. It's possible i have 3/4 swapped. But this thing has serious AFT intrusion in the harness from the trans range sensor. The black/lightblue wire runs everywhere, which is pin 4, I believe. Stuff i printed is outside in my truck and it's pouring right now.

Try again...keeps saying 'failed to upload"

Ben wrote: Don't mean to cut in here but could the pins be in the wrong place in the 2-2 connector? Or possibly the wrong sensor ? Is this a 3 or 4 wire sensor?

Sent from my SM-N920P using Tapatalk

Exactly my thoughts. Either the pins are swapped, or there's something wrong with the B2S2 O2. I'll see if I can find a connector end view tomorrow.

You could also try swapping downstream sensors bank to bank. Don't even install them, just hook the B1 sensor to the B2 connector, see if it still behaves the same way.

Gotcha defiantly get pins 3&4 straightened out I would bet that's the problem

Sent from my SM-N920P using Tapatalk

I've done that. Have a spare new sensor also. When I started they had the sensor connectors swapped side-to-side. 02-2 goes wonky soon as a sensor is plugged in. I have the connector view now but can't seem to upload it.

One. More. Time.

GTaylor wrote: I've done that. Have a spare new sensor also. When I started they had the sensor connectors swapped side-to-side. 02-2 goes wonky soon as a sensor is plugged in. I have the connector view now but can't seem to upload it.

Email it to me? wrenchturnsyou@gmail.com

You're thinking the heater pins are swapped? I'm not sure that'd cause this issue or not...

NO. Clearly stated above 1&2 are heater. I do NOT have a heater code or issue. i have a SENSOR code. I have 4.88-4.96V at ALL four sensors when unplugged. Can connect all except 02-2 w/o change in bias. When 02-2 is plugged in voltage gets pulled down on that sensor. Since it starts at a lower voltage, when heater warms it up, voltage drops to zero, which codes.

Hey tyler i had to read that several times From what I can tell the signal wires are swapped. pin 1&2 are heater and 3&4 are how i understand it. I agree if heater wires were crossed it would make no difference

Sent from my SM-N920P using Tapatalk

GTaylor wrote: NO. Clearly stated above 1&2 are heater. I do NOT have a heater code or issue. i have a SENSOR code. I have 4.88-4.96V at ALL four sensors when unplugged. Can connect all except 02-2 w/o change in bias. When 02-2 is plugged in voltage gets pulled down on that sensor. Since it starts at a lower voltage, when heater warms it up, voltage drops to zero, which codes.

I gotcha, just misread your post. My mistake!

Yeah...getting frustrated with this boards software. Really slow and glitchy for me.

Think it's fixed. Will see what is does on cold start in the morning.

Great did you find anything else or was it just the wiring issue ?

Sent from my SM-N920P using Tapatalk