2005 Chrysler Town and Country multiple codes

Hi everyone, I'm helping out a friend with her van, and at the same time getting a free chance to learn and poke around while it's parked in my garage.

The van is a 2005 Chrysler Town and Country LX, 3.3 L engine; runs fine, but just so-so

I first scanned it for her because her CEL was on, and I think it had 16+ codes. That was a few weeks back. I scanned it again this weekend and it has lots of codes. So I cleaned a few things, cleared the codes, and all these immediately come back (haven't driven it around yet, this is just running in the garage or key in ignition but not started):

P0032 HO2S Heater Control Circuit High B1S1 (O2 sensor replaced by a shop recently)
P0123 TPS Switch "A" Circuit High
P0038 HO2S Heater Control Circuit High B1S2 (both O2 sensors replaced by a shop recently)
P0406 EGR Sensor "A" Circuit High
P0122 TPS "A" Circuit Low
P0113 IAT Sensor 1 Circuit High
P0405 EGR Sensor "A" Circuit Low

Plus there are several pending codes and these show up in the Occupant Classification Module Codes:

RF Sensor Continuity Failure
Over Voltage
Bus System Communication

I've already got the manual and am going to backprobe some of the sensors and check voltages and then trace them back to the PCM, but does this sound more like a bad PCM? When I look at the repair reports on BlueDriver that is the common theme. It looks like everything is wrong with this one.

The only other thing I can think of (single-solution fixes) is maybe a bad ground somewhere, or maybe bad connections at the PCM. It's mounted inside the left wheel well behind a piece of plastic so I could imagine it might be dirty or may have gotten wet at some point. Doesn't seem the best place to put a PCM.

I'm going to take a look at the PCM tonight, but where would you guys start with that many codes? Have you dealt with anything that bad before?

Wow, all those codes come back right away? :ohmy: Well, at least it's not an intermittent problem! :lol:

If you have scan data available, then I'd start with a look at the TPS readings, and the IAT. No substituted values are allowed on Global OBD, so seeing something like -40 degrees on the IAT would reflect the P0113 IAT Circuit High code.

As far as wiring checks, I'dprobably start with the EGR or the TPS first, just 'cause they're easily accessible. Check voltage on all three TPS wires, and all three potentiometer wires on the EGR, backprobed with the key on. We're looking for a 5V reference, signal and ground on both. We have both Circuit High and Circuit Low codes for both the EGR and TPS, so it'll be interesting to see what you find. What you see on those wires will tell us where to go next.

Here's a couple diagrams to give you a better idea of what to look for on the TPS and EGR.

Thanks a ton. I have the pdf manual and was looking at those exact same pictures! I appreciate you putting them up, though.

Also glad it's not intermittent. It took me months to find a intermittent short in my Ford Freestar. So frustrating, but so awesome when I finally nailed it down and located it and fixed it!

Here's the readings from the TPS and ERG. I was using a quality DMM but not a scope.

TPS: I wasn't able to back probe it (no room for a pin) but I "front probed" the connections on the harness.
3. 5 volt supply: 3.6V one time I read it, 4.7 another time I read it.
2. TP Signal: 3.6V one time, 4.7 the other; the same reading as the reference signal (keep in mind this is unplugged from TPS)
1. Ground: 60 mV

Is that signal wire odd? I thought it was supposed to run up to 5V at WOT, not at idle?

ERG: was able to back probe it
Potentiometer section:
2. 5V supply: 5 V
3. Ground: 1.2 mv
1. Solenoid signal: started at 30 mV, rose to 300 mV, then "no signal" then repeated; rising and resetting every five seconds or so

Solenoid:
4. Ground: 1.2 mV
6. Solenoid Control: started at 30 mV, rose to 300 mV, then "no signal" then repeated; rising and resetting every five seconds or so

Not sure about that oscillating signal. The 5V signals and grounds make sense, but not sure about the oscillating signal.

Thanks for any help!