1998 Jeep Cherokee P0123 and P1597 Codes: Fix with Clock Spring Replacement
I have a 1998 Jeep Cherokee Sport and am still receiving the P0123 and P1597 diagnostic trouble codes after replacing the throttle position sensor (TPS). The TPS part was verified as good, and we've tested it at both open and closed positions—results were consistent. The engine runs smoothly, but the check engine light remains on. This issue first appeared during a recent drive when both P0123 and P1597 codes were triggered. I'm completely confused about what P1597 means, especially since my vehicle has no other noticeable symptoms. My tags expire at the end of November, and I’m worried that an appointment will tow the vehicle if I don’t resolve this soon. I’ve been advised to check the voltage on the TPS return wire at idle—this may be a key diagnostic step. Additionally, I noticed my horn stopped working about two months ago, and the airbag light has remained on since I've owned the car. Cruise control no longer functions (though I don’t have it), and I suspect these issues are related. I’m now considering replacing the clock spring as a potential root cause—this component is part of the steering wheel wiring and can introduce feedback signals to the TPS, leading to incorrect readings and persistent codes.
Check the voltage on the TPS sensor return wire at idle. Post your reading for accuracy. Also, let us know if you're experiencing any other symptoms—such as airbag light on, cruise control failure, or horn inoperable. P1597 indicates a 'Speed Control Switch Always Low' condition. A faulty clock spring (a component in the steering wheel wiring) can cause feedback signals to the TPS, leading to false readings and persistent codes.