2003 Toyota Gr. Caravan P0106-P0122-P1496 Fault: Idle Dies After Throttle Release
My 2003 Toyota Grand Caravan has recently developed three diagnostic trouble codes: P0106, P0122, and P1496. The vehicle runs well initially but begins to idle poorly—when I release the throttle, it stalls immediately. After replacing both the Throttle Position Sensor (TPS) and Manifold Absolute Pressure (MAP) sensor, the codes persist. The P1496 code specifically reads '5 Volt Supply Too Low.' I'm seeking advice on how to diagnose and resolve this issue. The vehicle appears to be losing power at idle after throttle release, which is concerning. I suspect a grounding or reference voltage issue related to the 5V signal, possibly involving one of the sensors or wiring harnesses. Next steps: I plan to check for a shorted 5V reference using a digital multimeter (DVOM) with the key off, testing each relevant sensor (TPS, MAP, A/C pressure sensor, EGR solenoid) individually while unplugged. If any show a grounded 5V signal, that may indicate a wiring fault or faulty component.
The P149-than code is likely the key starting point—this suggests a shorted 5V reference voltage. Begin by checking the 5V signal at the TPS with the ignition off, then unplug each sensor (TPS, MAP, A/C pressure sensor, EGR solenoid) one by one to isolate the fault. Use a digital multimeter to verify if the 5V reference is grounded or shorted. This could point to a wiring issue or a defective sensor. Note: These codes are unusual for a 2003 model and may indicate an underlying circuit problem.