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P0108 P0122 P123 P0203 P1478 P1496 P1598

Fix codes P0108 P0122 P123 P0203 P1478 P1496 P1598 on Dodge Grand Caravan, Plymouth Voyager

Site reader Becky wrote this post on ricksfreeautorepair.net: we have a 2002 voyager and have recently started having major problems, the codes that we currently have are P0108, P0122, P123, P0203, P1478, P1496, P1598. We have already replaced the TPS reset codes and still have the codes related, we have also checked and replaced the #3 fuel injector. Please help, Thank you

Here are the codes and their descriptions:
P0108 – Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0122 – Throttle/Pedal Position Sensor/Switch A Circuit Low Input,
P0123 – Throttle/Pedal Position Sensor/Switch A Circuit High Input
P0203 – Injector Circuit Malfunction – Cylinder 3
P0147 – Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
P1496 – 5 Volt Supply Output Too Low
P1598 – A/C Pressure Sensor Volts Too High

Becky’s description of how they approached the problem is a perfect example of how not to do diagnostics. If we look at the codes and their descriptions we see that all of them have to do with circuit issues. Either we have a 5 volt circuit that’s too low, A/C pressure too high, and assorted other sensors with voltage that’s high or low. Becky made the classic mistake of seeing a sensor listed in the trouble code and assuming that that automatically meant the sensor was bad. But would the MAP, TPS, Injector, O2 sensor, and A/C pressure sensor all be bad at the same time. Not only unlikely, but just about impossible. What’s far more likely is a wiring problem. What’s needed here is a wiring diagram to find out what wiring harness connection all of these items have in common. The wiring diagram for these sensors shows a connector located near the coil pack. Now I know that shops are finding this connection to be a trouble spot because I read their reports. They’re finding melted wires at this point. The melted wires deprive some circuits of power and add too much power to other circuits. But anybody could have found this problem if they take a logical approach. The fix is to disassemble the melted mess of wires and splice in new ones.

What have we learned? Well, we have a case where we see 7 trouble codes that all report circuit problems. Since it’s highly unlikely that all sensors are bad, it must be a wiring problem. Get a wiring diagram and find where the common connections are located in the vehicle. Then start at each sensor and follow the wires back to the connectors.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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