PO503 error code
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Junior Member
Joined: Jun 2012
Posts: 12
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From: Illinois
PO503 error code
Hi All,
I have a 97 F150 4x4 with the 4.6 I just purchased a few days ago. Seems like a pretty good truck all in all, however the overdrive off light started flashing. I am not having any issues with the speedometer and it is shifting just fine. To be on the safe side I had it put on a snap on reader for transmissions and it gave the PO503 error code I checked the speed sensor looked good cleaned it to be safe, still the same thing. Since the sensor is $20 I just bought a new one, same thing still blinking. I checked the wiring from the sensor on up nothing is hanging on the exhaust all looks good. Where would you guys look next. The truck starts and drives fine, so I wouldn't think PCM would be an issue but stranger things have happened. Fuses were good also what should the readings to the plug to the speed sensor be? Normally when I start the truck it does not flash, it will also not flash if I am driving low speeds, it only begins after 2-4 miles of highway speeds
Thanks guys for all the help
Jennifer
I ran by and got my truck put back on the reader the PO503 error is fixed but a new code came up P1500, so I went home and took the input/output sensor out and cleaned it really good, it was pretty filthy put it back in and ran back and got it scanned again the light was still flashing but said no codes found. Reset the computer and drove 2 drive cycles and the light finally stopped and I drove several hours today and it is still off so looks like I was pretty lucky $50 for the initial reading and he said he would read it until I got it fixed and $20 for the VSS and had I needed to change the input/output sensor on the trans it was another $25 I may go ahead and change it just to be safe. also it's helpful to know if your lock up converter is working, what you do is at highway speeds 55-60 just barely tap your brake pedal you can stay on the gas and use your other foot to just give it a tap so the brake lights would come on but not enough to engage the brakes, at that point you should notice your rpm's jump up about 3-4 hundred
hope this helps somebody
I have a 97 F150 4x4 with the 4.6 I just purchased a few days ago. Seems like a pretty good truck all in all, however the overdrive off light started flashing. I am not having any issues with the speedometer and it is shifting just fine. To be on the safe side I had it put on a snap on reader for transmissions and it gave the PO503 error code I checked the speed sensor looked good cleaned it to be safe, still the same thing. Since the sensor is $20 I just bought a new one, same thing still blinking. I checked the wiring from the sensor on up nothing is hanging on the exhaust all looks good. Where would you guys look next. The truck starts and drives fine, so I wouldn't think PCM would be an issue but stranger things have happened. Fuses were good also what should the readings to the plug to the speed sensor be? Normally when I start the truck it does not flash, it will also not flash if I am driving low speeds, it only begins after 2-4 miles of highway speeds
Thanks guys for all the help
Jennifer
I ran by and got my truck put back on the reader the PO503 error is fixed but a new code came up P1500, so I went home and took the input/output sensor out and cleaned it really good, it was pretty filthy put it back in and ran back and got it scanned again the light was still flashing but said no codes found. Reset the computer and drove 2 drive cycles and the light finally stopped and I drove several hours today and it is still off so looks like I was pretty lucky $50 for the initial reading and he said he would read it until I got it fixed and $20 for the VSS and had I needed to change the input/output sensor on the trans it was another $25 I may go ahead and change it just to be safe. also it's helpful to know if your lock up converter is working, what you do is at highway speeds 55-60 just barely tap your brake pedal you can stay on the gas and use your other foot to just give it a tap so the brake lights would come on but not enough to engage the brakes, at that point you should notice your rpm's jump up about 3-4 hundred
hope this helps somebody
Last edited by jturner97; Jun 3, 2012 at 10:21 PM. Reason: update for error fix