Engine/Transmission (1998.5 - 2002) APPS voltage

[rekabeka]

I have a 2000 Ram 2500, Cummins and 6 speed with 146,300 miles. I have a "check engine" light and the code reads "P0121". My shop manual indicates a voltage mismatch in the APPS or Throttle Position sensor. Is there anyway to clean that sensor or do I have to replace it? Anything in the past issues of TDR? I have all of them back to 1997. I just replaced the "Crank Position Sensor" and I'm running at Stage 1 on the Smarty. Thanks.

 

[RBeard]

There is a reset procedure to realign the APPS to pedal. Sitting in truck turn key to on position,slowly push accel. pedal to floor and let it up slowly. Turn key off. APPS resets and MIL light usually goes off after 3 start/stop cycles.

 

[VolsFan]

On my old truck, I went through the reset procedure and it lasted a little while, but I ultimately had to get a new APPS. I remember doing just what Rbeard says but I thought I also disconnected the neg battery terminals as well.

 

[RBeard]

I forgot about that part. It's just a matter of time til it goes out. I ended up with Timbo's APPS, now available at GENO'S.

 

[PC12Driver]

The various APPS reset procedures were quite a fad a few years back. The method described above is only useful if a) a new APPS is installed or b) the ECM has had battery power removed for a long enough time that it forgot the voltage range of the APPS. If this does "fix" the problem, assume the APPS is on its way out and get a replacement on the way.

Anyway, at 146k miles the original APPS has lived a good life. The contacts are pretty fragile and will wear quickly and start to introduce noise (like a scratchy volume knob on an old radio) and could set the 121 code. The Timbo APPS has a more robust internal construction, so it's an upgrade as well.

 

[rekabeka]

OK gang, thanks for the input. Code is clear for now? I will order a new APPS from Geno's so I will be ready for doomsday. Thanks again all.

Dave Mitchell