Have a 97 grand caravan with code P1493,P0117, &P0137 all at the same time. the check engine warning light is displayed along with the low battery warning light. Also the temperature gauge does not move from cold even after engine has warmed.

Most threads here have suggested bad PCM, any other options or suggestions.

thx in advance

 

P1493: Battery temperature sensor low voltage
P0117: Engine coolant temperature sensor low voltage
P0137: O2 sensor voltage low

Have you checked the battery and connections? What have you done so far?

 

- battery has been checked reading 12V when off around 13.53V when running
- checked the connections to the alternator, swapped out the alternator with a new one
- replaced thermostat and replaced the engine temperature gauge

None clear the codes. do I have to clear the codes after all these have been replaced?

 

could it be the serpentine belt?

 

Yes, the codes will be stored until you clear them with a reader. Or disconnect the battery for a half hour or so. I'd grab a haynes or chiltons manual it will have diagnostic checks for the proper voltages that should be coming from the sensors. If you have replaced all them, then it could indeed be the PCM or a wiring issue between the sensors and PCM. Might try unplugging and plugging back in all sensor connections and PCM connections, maybe some corrosion interferring with signals.

 

thx. will try to look for bad connections before trying a new PCM

 

When you get multiple sensor low voltage codes I have to wonder if the reference voltage is there. Might check at each connector - 117 engine temp sensor, 137 upstream O2 sensor and 1493 bat temp sensor. The battery temp sensor is either on the battery tray or built into the PCM. For the later you're SOL. The PCM supplies it but that circuit powers several additional sensors.

 

Where are all the ground wires for the engine compartment? Not skilled at reading wiring diagrams so diagrams, pictures etc would be very helpful.

thx in advance