Having a heater issue with bank 2 sensor 2... I want to make sure the harness connector to the pcm is in good clean shape, but don't know which plug it is.

Also, anyone remove the pcm and have tips? I assume its the control box on the underside of the fuse box in the engine compartment...

 

Your PCM in the silver colored box with 4 connectors in it on the firewall on the passenger side.

You can use the links in my signature to go to the thread and download a free copy of the service manual that has lots of stuff in it including electrical connector diagrams

 

Thanks... glad I asked before I started messing with the fuse box. There is only a bazillion wires connected to that pcm. It due for inspection tomorrow, I'm going to let my mechanic take a shot.

 

Not uncommon for the 02 sensor to work fine, and the heater circuit to go bad. Only fix is sensor replacement.

 

Inspection guy had it for a couple days, said he spent 3 hours doing diagnostics and was 90% sure it was a bad wire... but needed it next week for another test, then might need it for 2 days if he had to get into the harness... He didn't tell me what tests they did...

So back in my corner.... Using the manual Weed turned me onto... I found it looked like k399 wire was the heater feed. I found that pin 10 on the white PCM connector was where that wire hooked up.

I cut the original o2 sensor off the wire pigtail, stripped the heater wire and the gnd. Plugged my test harness into the truck side harness, then tested the voltage between the battery negative post and the heater wire...turned key on, crawled back under the truck, DMM showed like 0.6V.

So then I pulled the battery positive cable off and caused power drain to make sure any stored capacitance was gone. Pulled the white PCM connector, contacts were clean. Then I hooked battery ground to the k399 wire, clipped my test lamp lead on the positive battery post... and touched pin 10 on the white connector. Lamp lit right up.

I used the test lamp to make sure I was drawing some current, DMM can fool you sometimes.

For extra assurance, I then tested resistance on the k399 wire... DMM thinks its good.

So, I'm thinking I have a bad PCM. Opinions? Any other tests I should do? Where is a good place to source a replacement PCM?

Thanks!

 

I put my heater signal volt test to the driver side, surprised.... it does go up in voltage, but quickly settles out to 0.6v. Retested the passenger side, and I find the same pattern. Not really a smoking gun on the PCM like I thought.

I searched for that heater gnd wire in the manual, doesn't show up anywhere else. Thinking that gnd doesn't go back to the pcm.

Next steps?

I guess I could swap sensors and see if I can validate I have a known good one by using bank1.

I could try adding a wire to battery negative, to that bank 2 gnd wire... see if the code goes away.

I could swap the PCM and see if that happens (surely my most expensive and time consuming route).

 

If you need a PCM, check out www.solopcms.com

Later this afternoon I will try to check my AllData for troubleshooting steps

 

If you need a PCM, check out www.solopcms.com

Later this afternoon I will try to check my AllData for troubleshooting steps

 

Thanks!

I swapped sensors, same code. I found a ref on line for a durango about resistance of the heater gnd, I put my test cable on it... 0.1 ohm to gnd measured with my DMM. I guess I could have tried my test lamp on it, I'm always a bit skeptical about that Fluke 78 DMM when it comes to higher current circuits, got burned once error checking a sensor on a clothes drier. I got schooled by an appliance guy, using his cobbled up light bulb test ! :-/