A customer brought their 2017 Dodge Ram 1500 into an auto shop, concerned that the malfunction indicator light (MIL) was on, the idle speed was fluctuating, and there was a noticeable lack of throttle response. He also mentioned that the problem was intermittent. 

Case details

After connecting a scan tool, the technician found the following diagnostic trouble codes (DTCs):

• P0653- Sensor Reference Voltage 2 Circuit High
• P2127- Accelerator Pedal Position Sensor 2 Circuit Low
• P2181- Cooling System Performance
• P2681- Engine coolant bypass Valve Control Circuit Open

When the technician called an ALLDATA Tech-Assist, he gave the consultant the DTCs and said that he had found 5.02V on both 5VREF circuits at the accelerator pedal. 

The consultant advised that the same 5-volt circuit was connected to the manifold absolute pressure (MAP) sensor, camshaft position (CMP) sensors 1 and 2, Accelerator Pedal Position (APP), fuel rail pressure and coolant temperature valve. Since the coolant temperature bypass valve also had a 12-volt power supply going to it, there was a good chance that it was spiking the 5V reference circuit when it was shorted.

He suggested beginning the diagnosis by disconnecting the coolant temperature bypass valve to see if the symptoms subsided. As suggested, the technician disconnected the valve and the symptoms went away.

Confirmed repair

The technician replaced the coolant temperature bypass valve, cleared the DTCs, and road-tested the vehicle. There were no further issues. Problem solved!