Chrysler Repair: 2001 Dodge town & country van: fan control circuit, powertrain control module, throttle position sensor

Question
QUESTION: Hello,  I have this van and it has 4 codes on it PO106,PO122,PO1491,PO1496. COuld you tell me about this?

ANSWER: Hi Doug,
I assume you have a 3.3/3.8L engine. The first three are related in that the sensor require a 5 volt supply voltage to operate:
0122 Throttle position sensor signal voltage low
0106 MAP sensor signal voltage low
1496 5 volt output voltage low (probably the cause of the first two codes)

1491 a problem in the radiator fan relay circuit (probably the relay itself has gone bad).

The 5 volt output (pink/yellow wire) comes from pin 61 of the powertrain control module. I would begin by unplugging the sensors and then checking whether that color wire is shown as shorted to ground. Then unplug the 41-80 plug at the pcm and check whether the wires are patent between pin 61 and the sensor. Then verify whether when the ignition is 'on' whether you do or don't show 5 volts on the wire. I believe you will find a short in the harness from the pcm to one or the other sensor, or an open in the wire.
The fan relay is a solid state device that is mounted in front of the radiator on the lower cross member. It probably has failed as these seem to have a fairly high failure rate.
Roland

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QUESTION: Hello, I found the short I had. I replaced the rad. fan relay circuit with a new one but the fan still won't come on. Is there a temp sensor somewhere? Thanks Doug

Answer
Hi Doug,
There are a couple of reasons for no fans: A blown fuse 27 in the power module box under the dash. The fan relay is activated by a signal from the coolant temp sensor being sent to the powertrain controller which then actuates the relay. The temp sensor is located at the front of the engine on the lower manifold next to the thermostat housing. It has a dark blue/dark green wire and a violet/orange wire. It should measure about 7,000 to 14,000 ohms when cold and  then drops to around 700-1,000 ohms when the coolant is at operating temperature, using an ohmmeter placed across its terminals. That sensor could be off-value or the wires could be compromised. The blue/green goes to pin 43 of the pcm and the violet/orange to pin 26.
Roland