'08 Ram 2500 6.7 No Comm to O2 Module U011A

Year: 2008
Make: Dodge
Model: Ram 2500
Eng: 6.7 Liter Diesel Cummins
Trans: 6 Speed Auto
4x4
Miles: 125,674

This is a recent purchase that came with the MIL lit up. The only engine code is a U011A which states there is no communication from the ecu to the O2 module located on the Passenger side chassis rail.

Actions I've taken: Checked for power (Pink/Yellow - Ignition run start pin 9) and ground (Black wire- pin ten) at the connector at the module. Both showed to be good. I then back probed the wire that goes to the ecm (white and orange wire -pin 11-high data link). The following video shows the results. To my untrained eye it looks like the signal cuts out so i check ground and my t pin and both were good.

Videos will be coming soon photobucket is giving me a hard time. The videos are the live data via solus ultra and the scopes reading on the out put from the o2 module.

I'm excited to see your video, sir! I believe this is actually a NOX sensor module? I'm admittedly weak on these systems...

Vantage Pro sendvid.com/qpck6t2o

vid292.photobucket.com/albums/mm14/ephot...1845_zpsijr8agk5.mp4

I went and grabbed a diagram for reference, thought I'd share:



Thanks for the video! I dunno what all that noise is, but I can see why the PCM is pissed off about it. The diagram doesn't say this is a CAN network, but I can't imagine what else they'd use in this application. You'd expect the voltage on the high side of the network to be from 2.5V to 3.5V, but that's nowhere close. Does the low side look similar?

Also, I see that you've got your scope set on a 100us time base, which is pretty darn fast :ohmy: You might get a better idea of what's going on if you zoom out a bit, maybe 5 or 10ms? I find that's usually fast enough to see detail on network signals.

I'd be very curious to check the resistance across both network terminals, unplugged, at the sensor module connector. The reading you get will tell us if it truly is a CAN network, and if the wiring is good or not. With the sensor module unplugged, I'm hoping for a reading of 120 ohms - that would mean good wiring, and the correct resistance of the terminating resistor in the PCM.

what does the signal look like at the dlc? clean? im curious if you could run a new wire temporarily and see what happens. any other modules that don't communicate?

I will get to do all this tomorrow, I'm new to using a scope, meaning I'm not always sure what time base to use for what type of signal. A sticky to help identify time for signal types would be a great help to us none edjumaacated (educated) folk.

All other modules are working fine.
I'm not sure what DLC stands for.

Measuring resistance from the high to low signal wires I receive a 61 ohms. Which is about half of the figure that you all quoted I will upload the video and another of the signal that i receive.

What should be the next step from here, being new to using a scope I'm a bit lost as to where to go, wire lay over?

Josh

A sticky to help identify time for signal types would be a great help to us none edjumaacated (educated) folk.

Hey, not a bad idea! I may run with this

I'm not sure what DLC stands for.

Sorry sir, Data Link Connector.

Measuring resistance from the high to low signal wires I receive a 61 ohms. Which is about half of the figure that you all quoted I will upload the video and another of the signal that i receive.

61 ohms? With the sensing module plugged in, or unplugged? Not trying to nag, just need to be clear.

What should be the next step from here, being new to using a scope I'm a bit lost as to where to go, wire lay over?

The 60 ohm measurement makes me think there isn't a wiring problem, as this is exactly the resistance a CAN network should have at rest with both terminating resistors intact. To me, if we can prove wiring integrity and that the PCM is OK, then I think you're safe to sell a sensing module.

Just FYI, this sensing module talks to the PCM on it's own exclusive, dedicated network. Sure, there's other CAN networks on the vehicle (for the ABS, instrument cluster and such), but none of those are involved in this circuit. Mostly, I'm trying to establish if this sensing module network plays by the usual CAN network rules. That's what the resistance measurement was for

61 ohms? With the sensing module plugged in, or unplugged? Not trying to nag, just need to be clear.

That was all modules plugged in with the key in the off position. I want to get a video of the graph again but won't be able to until tomorrow.

Should I go about checking the signal from each o2 sensor to the module to see if that is were the issue begins. If so what steps should one take?

ephotrod wrote: That was all modules plugged in with the key in the off position. I want to get a video of the graph again but won't be able to until tomorrow.

Sweet! That's a perfect reading with all modules plugged in, and also positively ID's this as a CAN network. I feel pretty confident that there isn't a wiring issue at this point.

The 120 ohm reading I quoted would be if you had either the sensing module or PCM disconnected.

You could check the sensor wires, but I don't think that would account for the waveform you saw on your scope, or the network code. No service info here at home, but I believe this system would set a different code if it was just a sensor not performing correctly. I'll check on this tomorrow.

No worries about the next vid, though I'm happy to check it out when you can upload it. Really, I'd like to see the voltage on the high side above 2.5V with the sensing module disconnected, as it should never go as low as you were seeing.

Tyler,
Thank you I'll get a couple more videos (so i can learn) before we replace the module and one after. I'm doing alot of this to learn, I never went to a formal school or was taught how to work on cars, this is a great opportunity for me. Your and Pauls efforts are greatly appreciated. I've bought both books and have a years subscription to his channel, but guidance like your giving me is worth more than it all. Thank you.
Josh

No problem, sir! I'm happy that you brought this issue here, as I've never had to get my hands dirty on one of these sensing module systems. We've gotten questions about them previously , but I didn't have a ton of advice to offer at the time...

Speaking of, could I talk you into doing some more experimenting? I'd love to have voltage readings on the six NOx sensor wires at the sensing module Looking at the pin designations on the wiring diagram makes me think it's wired like an air/fuel ratio sensor, but I'm not certain. No worries at all if you don't have the opportunity! Just trying to expand my knowledge of these systems.

I'll do testing but it would be so much easier to email you the videos and info this uploading to photobucket to fail ten times kicks my ass and makes me not want to participate.

No problem! wrenchturnsyou@gmail.com

No need to video the sensor voltages, just static measurements will work perfectly.

I had a glance at Mitchell today, and we're right on in our diagnosis and testing. Really strange, the OE flowchart wants you to check power, but not ground :huh: And only wants to know if the power feed is over six volts... Weak flow chart, IMO.

Tyler I'll get to the measurement this weekend as its in the back and won't be touched for a bit. Give me a list of test you'd like to run and I'll go through them, posting the results.

No worries, this is a backburner idea of mine.

Also, how many wires total are there at this module? The BBB Industries diagram I posted earlier showed 10, with one sensor connected. But the Mitchell diagram I found showed 16 wires, with two sensors connected.

IF the diagram I posted earlier corresponds to your truck, then I'm looking for voltage readings on pins 1, 6, 7, 14, 15, and 16. I'm gonna take a shot in the dark and say:

Pin 1 + 16: Pulsed power and steady ground
Pin 14: 2.5V steady
Pin 7: 3V steady
Pin 6: 2.5V, varying
Pin 15: same as pin 6

Could be WAY off :lol:

Tyler the vehicle follows the on demand wiring diagram and is 16 wires I will try to follow through with what you want as far as I can with my limited abilities.

61 ohms sounds correct. The ECM has a termination resistor and the variable geometry turbo actuator has the second.

If you have clean data square waves at the module it's probably a failed NOx sensor.

Prior to replacing it check for TSB's, If you have the Engine Serial Number I can try and check QuickServe for anything on cummins side.

The following are all my readings based on the on demand diagram. A vantage Pro was used on a 20 volt scale 5 ms time base. There are 16 pins all together.


Pin 1: 12.31 volts
Pin 2: 12.31 volts
Pin 3: 2.95 volts
Pin 4: 2.94 volts
Pin 5: 2.86 volts
Pin 6: 2.94 volts
Pin 7: 2.84 volts
Pin 8: 12.35 volts
Pin 9: 12.35 volts
Pin 10: .69 volts
Pin 11: .68 volts
Pin 12: .68 volts
Pin 13: 2.52 volts
Pin 14: 2.52 volts
Pin 15: 2.86 volts
Pin 16: 12.30 volts

I don't have clean data square waves based on either pin 3 (white) the low data link or pin 11(white and orange) high data link.