Truck went into limp mode with "ETC" warning light - stored P2122

[Jebb]

Today while driving I went to accelerate from a light and got a chime and a big red "ETC" warning on the instrument panel. A little red ETC warning light at the bottom of the panel also came on. The truck went into limp mode. It seemed like it was locked in second gear as it took more throttle than usual to get it moving and it wouldn't upshift once it was moving.

I drove another ~1/4 mile to my destination and parked for about 2 hours. Upon returning, I got in and it started right up. The check engine light was still on but the little red "ETC" light at the bottom of the instrument panel was now off and it drove completely normally (no longer in limp mode) for the 20 minute ride home. Full power, normal shifting, etc.

When I got home I put the scanner on it and it showed P2122 - Throttle Position Sensor Low. The red "ETC" light was still off so I decided to clear the codes and see what happens. I cleared the codes and ran it for awhile and no codes or warning lights came back on.

So, was this just a random computer glitch - or is something failing? What do I do about it if everything now reads "good"?

Truck specs in sig. Only has 16,000 miles on it!

 

[csuder99]

P2122 is a manufacturer specific code, and if you add "RAM" or "Dodge" to your google search it will point to the Accelerator Pedal Position (APP). Issues with the TPS will throw codes in the P0XXX range, and possibly some manufacturer specific codes in addition to it.

Probably not a computer glitch per se but a glitch with the APP sensor. I haven't checked but typically manufacturers use two separate position sensors for safety reasons (you don't want the engine to go wide open when it's supposed to be at idle). It might have been a disagreement between the two sensors that caused the issue.

 

[Jeepwalker]

Because it's cheap and easy to do, I would swing by Autozone, or another parts store, and get your battery load tested too (for free). And double-check batt terminal connections. You never know.

 

[NCRaineman]

Do you have a pedal commander?

Mine will do that on occasion if I change modes in the middle of a drive.

If no pedal commander stick your head down there and make sure your pedal is plugged in securely and not coated in dirt or grime.

 

[Jebb]

Because it's cheap and easy to do, I would swing by Autozone, or another parts store, and get your battery load tested too (for free). And double-check batt terminal connections. You never know.

Yes, I will check - thank you for those suggestions. It's a brand new battery (~3 months old). The truck started easy/normally and was running for about 20 minutes before this happened.

My scanner has a battery load test function - will give that a try. Will also check batt terminals and TPS connector.

 

[Jebb]

If no pedal commander stick your head down there and make sure your pedal is plugged in securely and not coated in dirt or grime.

Now that you mention it, I vacuumed the carpet in the truck the day before. What "pedal is plugged in" do you mean? Is there a connector at the gas pedal that could have been bumped loose? Will look.

 

[NCRaineman]

Now that you mention it, I vacuumed the carpet in the truck the day before. What "pedal is plugged in" do you mean? Is there a connector at the gas pedal that could have been bumped loose? Will look.

Yeah. The pedal is 100% electric, there's no old-school throttle cable going to the engine. It's literally plug-and-play. Could be loose or dirty. Is easy to find once you stick your head down there. If you get a pedal commander in the future that's where it hooks up... easy peasy.

 

[Jeepwalker]

A pedal commander BTW (OP), is an electronic device that goes in the wiring between the pedal and harness. It re-maps the throttle response and makes your truck feel more 'responsive' when you press the accelerator.

The reason a forum member asked if you had one on your truck is because the truck's computer can sometimes 'not like' them (after a long while) and start giving odd computer codes.

 

[Jebb]

A pedal commander BTW (OP), is an electronic device that goes in the wiring between the pedal and harness. It re-maps the throttle response and makes your truck feel more 'responsive' when you press the accelerator.

The reason a forum member asked if you had one on your truck is because the truck's computer can sometimes 'not like' them (after a long while) and start giving odd computer codes.

I understand why it was asked but no, I don't have a pedal commander.

I put the scanner on it again today to do a battery check (which read "Good" BTW) but I discovered there is a second DTC that I didn't see yesterday - U1428 "Engine Torque Request Signal Stuck". I don't have any idea what caused that but it may explain why it seemed it was stuck in second gear (until I shut off and re-started). Both of these codes show "Permanent" DTCs. Does this mean I am forced to visit the stealership?

Again, no lights are currently on in the instrument cluster and it drives normally - but I'm not sure I trust it now.

 

[Jeepwalker]

You might want to disconnect the battery terminals for a while and that will reset the truck computer. (write the codes down first). You might not have a problem again. If you do, then, yeah, you might want to take it to the next level (service or more DIY). Sometimes resetting the computer solves problems. Just like your computer... ha ha. And sometimes it doesn't (just like your computer)

Worth a shot

 

[Jebb]

You might want to disconnect the battery terminals for a while and that will reset the truck computer. (write the codes down first). You might not have a problem again. If you do, then, yeah, you might want to take it to the next level (service or more DIY). Sometimes resetting the computer solves problems. Just like your computer... ha ha. And sometimes it doesn't (just like your computer)

Worth a shot though

Yeah - that's an easy thing to try. Will do.

 

[NCRaineman]

I'd totally pull the negative battery terminal, step on the brake pedal for a good ten count (drains any juice left in the capacitors) then reconnect and go for a drive... see what happens.

 

[Jebb]

I'd totally pull the negative battery terminal, step on the brake pedal for a good ten count (drains any juice left in the capacitors) then reconnect and go for a drive... see what happens.

Just got back from doing exactly that!

Ran fine. No fault lights came on but the stored DTCs (P2122 and U1428) are still there and still show "Permanent". Don't know if they'll clear by themselves after 50 miles or not. We'll see. But in the meantime I'm a little hesitant to take this thing onto LA freeways or any long trips.

In everyone's experience, can this kind of thing "just happen", i.e., random computer glitch - or does it usually mean something is in fact failing?

 

[NCRaineman]

These darn things are so computerized now I'd be hesitant to accept one CEL and a couple of codes as a sign of anything. It will need a few drive cycles to fully clear stored codes and be good to go. If it comes back in a day or two you'll know there is a bigger problem to chase. If not, meh.

 

[Jebb]

It's been over 500 miles since the issue I posted here and all was well. The stored DTCs (P2122 and U1428) cleared by themselves after 50 miles - so I thought it was just a fluke

- but it happened again today.

I pulled up to a traffic light and a second later got a chime, check engine light and "Service ETC" warning on the instrument cluster. I felt the truck shift gear and on checking found it was in 3rd gear - while stopped - and stayed there regardless of speed afterwords (limp mode).

I got home, shut the truck off and then started back up and it was normal again. Check engine light is still on but throttle and shifting are normal.

Both times this has happened I had just come to stop at a traffic light (throttle closed, brakes on) with the engine not yet at full temp. Idle seemed normal.

So what's going on here? Could a sticking throttle plate (carbon) cause this? I checked the throttle and pedal e-connectors and all are tight. Truck only has 18k miles on it.

DTC codes point toward a bad Accelerator Position Sensor but I wasn't touching that pedal either time this happened (my foot was on the brake).

Any ideas?

 

[huntergreen]

It's been over 500 miles since the issue I posted here and all was well. The stored DTCs (P2122 and U1428) cleared by themselves after 50 miles - so I thought it was just a fluke

- but it happened again today.

I pulled up to a traffic light and a second later got a chime, check engine light and "Service ETC" warning on the instrument cluster. I felt the truck shift gear and on checking found it was in 3rd gear - while stopped - and stayed there regardless of speed afterwords (limp mode).

I got home, shut the truck off and then started back up and it was normal again. Check engine light is still on but throttle and shifting are normal.

Both times this has happened I had just come to stop at a traffic light (throttle closed, brakes on) with the engine not yet at full temp. Idle seems normal.

So what's going on here? Could a sticking throttle plate (carbon) cause this? I checked the throttle and pedal e-connectors and all are tight. Truck only has 18k miles on it.

DTC codes point toward a bad Accelerator Position Sensor but I wasn't touching that pedal either time this happened (my foot was on the brake).

Any ideas?

I guess you’re out of warranty, so I’d let a local mechanic fix it. It’s probably cheaper to have done than just throw parts at.

 

[Jebb]

I guess you’re out of warranty, so I’d let a local mechanic fix it. It’s probably cheaper to have done than just throw parts at.

I ordered a new Accel pedal/sensor assembly for less than what the dealer charges just to bring it in the door. Will give that a try first. But yes, I will stop at that first attempt. If it turns out to be a computer/wiring/other problem I will have to go to the stealership and face the music.

 

[huntergreen]

I ordered a new Accel pedal/sensor assembly for less than what the dealer charges just to bring it in the door. Will give that a try first. But yes, I will stop at that first attempt. If it turns out to be a computer/wiring/other problem I will have to go to the stealership and face the music.

No decent local mechanics near you ? Always cheaper than the dealership by me.

 

[Jebb]

No decent local mechanics near you ? Always cheaper than the dealership by me.

I'm sure there is but I don't want to shop-hop until I find one. Meanwhile I do know plenty of bad ones nearby who could actually make the problem worse...

My experience with local mechanics is that they typically have broad/generic knowledge and generic tools. They're good at basic repairs and maintenance but not for hunting down brand-specific computer/electrical problems, especially if something like an ECU re-flash is required, etc. I hate going to the dealership but hopefully they're experts. At least they should be!

 

[Udy2554]

I had a handful of “service etc” alerts a while back! Very similar to your experiences! The random alerts happened more and more often! Only went into limp mode twice! First couple times were on hot days also!

I replaced my accelerator pedal! Bosch is the OEM manufacturer! I found mine on Rock Auto! No problem since! Not very expensive!

I know it doesn’t apply to you, but I had a Pedal Commander…i discontinued using it! No idea if it caused a problem, but lost confidence!

Again, same issues as you…to a tee! Pedal solved it! (I never ran a code, so I don’t know if there were any, or what they were!)

Great luck to ya!