Good morning. I have a 2008 f150 5.4 TRITON v8 xlt. For the past 7 months, my truck randomly produces an error code. P2135 Thottle/Pedal Position Sensor/ Swith A/B Voltage Correlation. The wrench lite comes on and the truck goes into limp mode. I can usually clear by a couple of methods: turning off the engine, disconnecting the battery, clearing the code, or clearing the computer (PCM). This is usually a quick fix, but the problem keeps coming back.
I brought it to a mechanic. He replaced the throttle body. A week later, the problem came back and I brought it back in. He replaced the throttle body again, thinking it maybe a defective part. Ran some diagnostics, and eliminated the pedal sensor, the throttle body. Determined that there were 2 bad coils, started by replacing spark plugs.
Problem still persisted. I changed out all 8 coils, put a new battery in(probably not related), unplugged the throttle sensor, the pedal sensor, the coil wires and the three cables going to the PCM. Waited a couple of minutes and plugged everything back in. Next, I cleared the PCM by disconnecting the negative cable from the battery and connected with an alligator clip to the positive pole on the battery for 15 minutes. Reconnected the battery, turned off all accessories, turned key on and let ignition run thru its beeps and then started the truck, let the truck idle for 15 minutes to relearn everything. This was effective for four months. Now the problem is back again and driving me crazy.
As far as I can tell, the issue began after the serpentine belt was replaced. Last weekend, I had to replace the tensioner pulley assembly. I was hoping I had found the issue.
The problem persisted after 4 days.
The error code is thrown in various situations, as I have tried to monitor what is going on when it happens. 1. truck is idling and heater is on
2. after running truck on highway for at least 10 minutes and get caught in traffic, truck idles at 1800 RPM’s
3. running A/C unit
4. traveling at 65–75mph on highway, no idling, or after idling in traffic
I have heard something about the air intake causing this problem, but have not researched yet…
I have guessed that it is some type of wiring issue, but not sure where to look.