2002 Jeep Grand Cherokee P1598 P0753 P0123 P0051 P0031: Diagnosing Multiple OBD-II Codes and Engine Stalling

A failing PCM is less common than wiring or electrical faults—OBD-II codes do not directly indicate a sensor failure; many sensor-related code claims come from sellers promoting replacement parts. Your codes suggest electrical issues, such as low voltage signals in oxygen sensors (P0031 and P0051), a high throttle position sensor reading (P0123), missing vehicle speed signal (P0500), transmission shift solenoid or relay circuit failure (P0753), and an overvoltage A/C pressure sensor (P1598). These are often linked to shared wiring, power supply issues, or a blown fuse. A detailed wiring diagram would be helpful here. Have you made any modifications—such as remote starters, audio systems, or lighting upgrades? Such aftermarket components can introduce electrical conflicts. Specifically: P0031 – 1/1 O2 Sensor Heater Circuit Low P0051 – 2/1 O2 Sensor Heater Circuit Low P0123 – Throttle Position Sensor Voltage High P0500 – No Vehicle Speed Signal P0753 – Transmission 3-4 Shift Solenoid or Relay Circuit Failure P1598 – A/C Pressure Sensor Voltage Too High

Thanks for the prompt response. I haven’t made any modifications—only original factory components. The initial misfire may have been due to a faulty Throttle Position Sensor (TPS). When I tested it, I recorded 0.48V at idle (closed position) and 3.84V at full throttle opening. This reading seems off; I’m now considering replacing the TPS as a next step. Regarding wiring: how can I access an official wiring diagram? I’ll also check fuses for both O2 sensors. As for the A/C pressure sensor, I don’t know its location yet—will investigate once I locate it. Thanks again!

Has cruise control been working properly? Check fuse #5, #16, and #28 in the Power Distribution Box (PDC)—located under the hood. Do not just visually inspect; test continuity at both ends of each fuse. These fuses are critical for power distribution to sensors and systems like the TPS and A/C.

I don’t use cruise control, but I’ll check if it functions normally. I’ve already tested fuses #5, #16, and #28—they are all intact. Additionally, I reset the PCM, drove around the block, and then scanned the system—only P0753 appeared at that time.

How are you retrieving diagnostic codes? Are you using a dedicated OBD-II scanner (e.g., from AutoZone), or relying on the 'key dance' method? Is it currently only showing P0753, with no speedometer issues? Have you experienced any battery-related problems or had to jump-start the vehicle recently?

I’ve been using the key dance trick to retrieve codes. Today I repeated it and received both P0753 and P1598. The engine continues to stall, and transmission shifting remains problematic. I've read that adjusting the TV cable might resolve shifting issues—so I’ll try that next.

You should use a real OBD-II scanner capable of retrieving all stored and live codes. Has cruise control been affected? The codes point to electrical circuit faults. Specifically, check the transmission harness: is there 12V power at the green (ltgrn) wire for the shift solenoid? And is there 12V on the brown (brn) wire for the transmission control—both should have constant voltage when powered by the key (KOEO).

Adjusting the TV cable resolved the transmission shifting issue. The stalling problem remains. Recently, I discovered a small fuel leak from the fuel rail’s pressure damper. Research indicates this component is not repairable and requires replacing the entire fuel rail—possibly explaining the original misfire and stalling issues. While it may seem like an afterthought, this could have been the root cause all along. Thanks for your help!

Yes—the fuel pressure damper is part of the fuel rail assembly.

I took my Jeep to Advanced Auto Parts and had a professional scan performed. The results showed ABS 13, ABS 15, P0135, and P0753. Any thoughts on what these might indicate? Thanks for your input.