Code p2121, lack of power

wildmanben

wildmanben

Farmboy...
Joined
Aug 28, 2006
Messages
884
04 3500 with m/t. Has code p2121 APPS problem. Checked voltage, verified ok. Replaced APPS. Still has a lack of power. Up to 1/2 throttle its fine, but after that the CEL comes on and has no power. I tried resetting it also with no luck. Am I mssing something here that will cause this?
 
no help? Whats the max boost on a stock truck or what happens when it gets too much? Scanner says it has 14psi at idle and 41psi under load. Seems a little off?
 
SYMPTOM
P2121-APP VOLTS DO NOT AGREE WITH IDLE VALIDATION SIGNAL

WHEN MONITORED
While the engine is running.

SET CONDITION
IVS indicates idle while APPS signal voltage indicates not at idle condition or IVS indicates not at idle while APPS signal voltage indicates idle condition.

POSSIBLE CAUSES

* Other APPS DTC'S
* APPS
* (K851) 5-volt supply shorted to voltage
* (K22) signal circuit shorted to (K556) not idle circuit
* ECM
* (K851) 5-volt supply circuit in ECM
* Intermittent condition
* APPS
* Intermittent condition
 
Same thing that my MODIS told me. But a manual doenst have an IVS right?
 
wildmanben said:
Same thing that my MODIS told me. But a manual doenst have an IVS right?
Click to expand...

I think the IVS is just a signal??? but from what??


sounds and looks like it is a electrical short....but since you checked the wiring I don't know what to think???
if you have MODIS then I would follow the diagnosing steps it gives and if that turns up nothing the ECM is the last choice right???
 
Got another APPS on the way, if thats not it, its probably the ECM, $$$.

The IVS is a signal from the APPS off a auto. The manuals just had 2 rheostats to give a voltage signal to ECM. The Autos had a TPS and 2 IVS switchs. One that says 0 volts and the other says 5-12volts at idle and vice versa for WOT.
 
Replaced the APPS again. Works fine now. I guess I got shipped a junk unit?
 
cool glad you got it going......nothing worse then getting a junk part and spending time diagnosing other stuff thinking the part you just got is good:bang
 
I keep running into a 2121 too but its at just slight throttle, get into it it never happens. When I shift gears and let off the throttle and then get back in it I have no throttle and have to start pumping it till it comes back.

Is yours a 04.5 or just 04? I have the APPS in the pedal, its only a few months old but wandering if I have a junk parts as well.
 
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