2003 Dodge Grand Caravan 3.8L No Start MIL Lamp On

Vehicle problem question:

What could cause a 2003 Dodge Caravan with 3.8L engine to suddenly quit and no start? It has multiple codes like TPS, ECT, crank sensor and fuel pump which were all replaced. The ground and voltage supplies were OK which lead also to the replacement of the PCM. It only ran a few days and the vehicle quit again with the same multiple codes? This looks like a wiring problem but where do I begin?

ATS Adviser:

Shown below is the vref voltage circuit of 2003 Dodge Caravan. Please note, it is not enough to check the ground and voltage supplies of the PCM, you need to check the vref voltage for the sensors like: TPS, MAP and AC Pressure sensor to verify the voltage reference circuit (vref). If higher than 5 volts, its shorted to power, or if lower than 5 volts, it is shorted to the ground.

There is also the possibility that the vref wire from the PCM terminal is open and these must be checked. Do you know you can actually disconnect the vref terminal at the PCM to test if the vref circuit is shorted at the sensors? Of course you have to access it at the PCM instead of testing each sensors for vref one by one. Don't forget, vref measurement is done at KOEO.

You can get a FREE wiring diagram from most parts stores if you ask for it while buying parts or get it FREE online 24/7 when you join ATS.

Actual color of the wires at 5 volt refence sensors:

When testing these wires, do it at key on engine off (KOEO) after it warmed up and quit. Scanner with live data stream can actually see these in the monitor if done in a garage.

For Dodges 3.3L engines (same as 2.4L engine):

ground is dark blue green must not be higher than 0.1 volt
tps signal is brown orange
5 volt signal is pink yellow (for tps)

For Chrysler Town and Country 3.3L or 3.8L engines, it is the same colors. If changing the crank sensor does not work, replace the cam sensor before replacing PCM if you have a code P0340. To check crank and cam sensors wires:

ground is dark blue green must not be higher than 0.1 volt
crank signal is brown light blue
cam signal is dark blue dark green
8 volt supply is brown pink for both crank and cam sensor


This was the test I was looking for! After testing the vref from TPS sensor, it read almost 12 volts. Tracing the wires, we found the vref shorted to 12 volt supply which rub together which caused the short. Repaired the wires and replaced the PCM for the second time (guess it was killed again by the shorted wire). It has been running for over a week now with no codes. Thanks for your help.

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