Several issues, all electrical. Chrysler Town and Country.

schaffsschaffs Member Posts: 1
edited October 2014 in Chrysler
I have a 2005 Chrysler Town & Country LX 3.3L

It seems as if all of these problems started happening near the same time.

The first thing we noticed: when turning on the blower, it only blows heat and it only blows it out of the defrost location. In the Rear, it only blows cold.

Then, the headlights started to not come on. If this happens, you have to turn the lights on and off multiple times until they turn on.

Then, the vehicle started spitting and spurting, lurching as you're driving, almost as if it was cutting out.
This eventually resulted in a check engine light, which yielded code P0138 O2 circuit high voltage bank 1 sensor 2

Was going to replace O2 sensor, but perhaps something else electrical related seeing as how all of the other issues...?
HELP please!


  • thecardoc3thecardoc3 Member Posts: 5,631
    With multiple issues you have to create and follow a good game plan. Part of that is to not assume anything, especially the idea that the problems could be related in any way. Literally for the moment treat them like they are occurring on different cars. Now pick one and troubleshoot and solve it, then look to see if you just happened to have solved more than one problem.

    The O2 sensor code means that the voltage from the sensor is too high after a measured period of time after the engine was started. Correctly diagnosing that requires investigating when and why is the voltage high to begin with and what causes the voltage to drop. The PCM puts out a reference voltage on the O2 sensor signal wire and it see's that voltage that it outs on the wire. When the car is started the O2 sensor is cold and has a very high resistance so it cannot pull that reference voltage down so that the computer can see the O2 sensor's output voltage. It is the O2 sensors heater circuit that has to warm the sensor up to the point that it turns on, and pulls that reference voltage down. This should occur in about fifteen to thirty seconds after a cold start and is something that can be seen in the data stream with a scan tool.

    OK, so you have the description of how it works, now from a technicians perspective you have to prove what is actually going on. The heater circuit may have failed in the O2 sensor and many will simply tell you to just replace the part. When that works everyone treats what auto technicians do as menial. However, you could be missing power to the sensor for the computer to even turn the heater on, and a good routine has to check and confirm both power to the sensor and the PCM's ability to control it instead of just pull a code and toss a part, and that is what you are really paying for when a top tech is diagnosing a fault like this. At the same time it is possible to rationalize whether there is any possible correlation to the other symptoms (issues) described. Losing power to the sensor from the source would likely cause a loss of power to the other O2 sensors as well and since you didn't report similar codes for the other sensors that isn't plausible.

    Now once the O2 sensor issue is resolved, choose the next one you want to address, or of course don't start with the O2 sensor, start with the headlight problem. Either way you need the schematics for the system that you want to figure out, a fully capable scan tool to check switch inputs and perform bi-directional commands as required and then put a plan into use.
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