Hoss

On my way home from work today I lost all throttle response.

Just prior to the loss, I was sitting at an intersection and the truck idled up to about 1200 RPM's and held there. This was the first time that had ever happened.

I continued driving and while going down the highway in rush hour the truck suddenly lost all power. The engine continued running at idle but there was absolutely no throttle response.

I coasted over to the shoulder and ended up calling DC Roadside Assistant. They told me it would be two hours before they could have a tow truck to me and then they were going to take me to the nearest dealership (which was already closed).

I got out and checked my oil thinking maybe it was some sort of safety feature to prevent me from ruining the engine. All was good and all gauges were good (engine light still on).

I killed the truck and cranked it two or three tiimes. On about the third try the throttle response returned but the engine light was still on.

My truck is throwing the code P2121. I don't know what that code means but from reading here it sounds like I may have an APPS problem.

Can anyone verify that P2121 is the APPS? If so, is this a Mopar only part or can I buy it at Auto Zone and replace it myself?

BigBlue

P2121-Pedal Position Sensor 1 Conformance Error

Sounds like the APPS possibly. Try doing a search on ebay as I know they pop up hear and there on occasion. Other than that you better have some lube when you go to the dealer because they aren't cheap by any means. If you've got the extended warranty then I suggest letting them replace it on their dime.

Hoss

I've been given quotes of $280 and $375 for the same part from two different dealers. Go figure.

If P2121 is what you say it is then I think that pretty much confirms that I need a new APPS. I guess I can't complain too much though. After 3 years and 65,000 miles this is the first problem it's ever had.

Anyway, I ordered the part from my old dealership back up in Lewisville (where I'll be on Friday because we're moving this weekend). HOPEFULLY the one I have will make it that far. If not then I guess I'll have to get it towed in.

68ss

DRIVEABILITY - DIESEL
Symptom:
P2121-APP VOLTS DO NOT AGREE WITH IDLE VALIDATION SIGNAL
When Monitored and Set Condition:
P2121-APP VOLTS DO NOT AGREE WITH IDLE VALIDATION SIGNAL
When Monitored: While the engine is running.
Set Condition: IVS indicates idle whileAPPS signal voltage indicates not at idle condition
or IVS indicates not at idle while APPS signal voltage indicates idle condition. Or, the ECM
detected a conformance error between PPS 1 and PPS 2.
POSSIBLE CAUSES
DAMAGED WIRING HARNESS OR CONNECTOR
FAILED APPS
RATIOMETRIC CIRCUIT SHORTED TO NOT IDLE CIRCUIT
SUPPLY SHORTED TO 12 VOLTS
FAILED ECM
OTHER DTC’s
FAILED PPS
TEST ACTION APPLICABILITY
1 The diesel engine uses two types of throttle position sensors, depending on transmission
configuration and build date.
ENGINE- 5.9L
DIESEL
If the throttle position sensor is located on the engine
Go To 2
If the throttle position sensor is located under the battery on the driver side
of the vehicle
Go To 11
2 Using the DRBIIIt, check for any additional accelerator sensor fault codes.
Do you have any additional accelerator sensor fault codes?
ENGINE- 5.9L
DIESEL
Yes ! Troubleshoot other DTC’s first
Go To 3
No ! Go To 3
3 Verify that the APPS is connected.
Inspect the harness and the APPS connector.
Are any pins damaged?
ENGINE- 5.9L
DIESEL
Yes ! Repair or replace harness or sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 4
P2121-APP VOLTS DO NOT AGREE WITH IDLE VALIDATION SIGNAL —
Continued
ST ACTION APPLICABILITY
4 Measure the resistance between the ratiometric pin of the sensor and the not idle pin
of the sensor.
Is the resistance less than 10 ohms?
ENGINE- 5.9L
DIESEL
Yes ! Replace the sensor
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 5
5 Disconnect the ECM connector.
Inspect the connector for damage.
Are any pins damaged?
ENGINE- 5.9L
DIESEL
Yes ! Fix or replace the harness or the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No ! Go To 6
6 Disconnect the ECM connector and the sensor connector.
Measure the voltage between the supply pin of the sensor connector and battery
negative.
Is the voltage greater than 1 volt?
ENGINE- 5.9L
DIESEL
Yes ! Fix or replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 7
7 Measure the resistance between the ratiometric pin of the sensor connector and not
idle pin of the sensor connector.
Is the resistance less than 10 ohms?
ENGINE- 5.9L
DIESEL
Yes ! Fix or replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 8
8 Connect the ECM connector.
Measure the resistance between the ratiometric pin of the sensor connector and not
idle pin of the sensor connector.
Is the resistance less than 10 ohms?
ENGINE- 5.9L
DIESEL
Yes ! Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 9
9 Measure the voltage of the supply pin at the sensor connector and battery negative.
Is the voltage greater than 5.5 volts?
ENGINE- 5.9L
DIESEL
Yes ! Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 10
P2121-APP VOLTS DO NOT AGREE WITH IDLE VALIDATION SIGNAL —
Continued
TEST ACTION APPLICABILITY
10 Using DRBIIIt, clear DTC. ENGINE- 5.9L
DIESEL
Repair complete.
11 Using the DRBIIIt, check for any additional PPS fault codes.
Do you have any additional PPS faults?
ENGINE- 5.9L
DIESEL
Yes ! Troubleshoot other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER 1 (DIESEL).
Go To 12
No ! Go To 12
12 Verify that the PPS is connected.
Inspect the harness and the PPS connector.
Are any pins damaged?
ENGINE- 5.9L
DIESEL
Yes ! Repair or replace harness or sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 13
13 Connect the sensor connector.
Monitor the PPS 1 and PPS 2 voltage with the DRBIIIt while depressing the throttle
pedal.
Is the voltage transition shown on the DRB smooth while depressing the throttle and
is the voltage from PPS 1 twice as much as the voltage from PPS 2?
ENGINE- 5.9L
DIESEL
Yes ! Repair complete.
No ! Replace the PPS
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
212

Hoss

Thanks 68ss. I'm just going to replace the PPS and hope for the best.

scuzman00

I'm glad ya'll fingered that one out. I was gonna chime in that it could possibly be an in cab sensor that is refusing to let the Cummins run properly because it didn't want to be seen in public while Hoss was wearing his speedo...

I think I'll go crawl back under my rock now and watch out for thrown objects....

Gary

Hoss

I won't throw anything, but don't be surprised if a dirty speedo gets slingshotted your way.

Anyway....I drove home today and ditto. Within a half mile of where the pedal went dead it did it again today. I got it going again by turning the truck off and then on and pumping the pedal a few times and proceeded on. A few miles later it did it again. I got it going again and brought it home.

Unfortunately i won't have the new bell crank and sensor until Thursday evening. I sure hope that fixes the problem.

diesel_burner

Yeah that same thing happened to me a couple of weeks ago. But I was in Fargo North Dakaota at 12:30 in the morning and it was about 5 degrees outside. Go to reset the APPS and ended up looking my keys in my truck after I disconected the batt's. so instead of 30 mins it was 2 hours. but thank God I was at a truck stop so I just went and hung out with the pro. drivers in the professional drivers lounge. But the good news is it hasn't done that again yet. let's just hope it's not on a trip next time.