Throttle Pedal Cutting out Under Load

[NHuott]

Hello there. I've been battling this issue for a while now, with multiple dealer stays, always resulting in the same outcome.

The problem I have is when accelerating with a load. The throttle will cut out completely to 0%, and will not come back until you bring the pedal back to an idle and then push it down again. It does occasionally happen when driving just the truck alone, but it is a regular, repeatable occurrence when towing a trailer (Which for this truck is about 90% of its life).

So far the dealer has replaced the actual throttle pedal assembly (2x, we are now on throttle pedal #3), they have replaced the VGT actuator, and now are telling me they need to replace the EGR Valve for a whopping $3,500.

I have checked some things over with my Autel scanner and find that when the problem happens, I lose 5v supply voltage to the throttle pedal. I have taken a video of this happening and I can try to post that as well.

Please help me out!

 

[Ozymandias]

That's a good start with the 5V supply!
Try to find out if other appliances loose there 5v supply too. Probably yes.
Then try to isolate which shorts out to make the supply stop from BCM.
It can be as simple as a pushed back Pin in one of the connectors.

 

[NHuott]

I tried looking on the scanner for another 5v supply to see if it was dropping as well. The only other 5v supply I was able to find was for the fuel level sender (If I recall correctly). It did not drop when the pedal supply did.

I can look again, but I think that was the only other available 5v supply that I could see within the set of menus that I was in. I do hope it is something relatively simple though like you said!

 

[Ozymandias]

Fuel level is a calmed down gauge, it takes some time to move. Otherwise the needle would just jump up and down with the fuel sloshing around in the tank.
That's the reason why the needle doesn't move with the 5V loss for a short time.

5V is everywhere in the vehicle, everything electronic, all sensors and so on run on 5V.

Let's see what ideas others have to dive into that topic.

 

[NHuott]

I was looking at the 5v supply for the fuel gauge, not the 0-5v reference. It stayed steady when the 5v supply for the pedal wigged out. Although if it were on a different circuit, it might not drop? I wish electrical was my strong suit!

I do agree, I will take any and all advice from you guys here! Always good to have a few brains pick at a problem.

 

[Ozymandias]

The whole dash is controlled through the BUS system, nothing hardwired there from what I know.
The fuel sending unit reports to the ECM and from there it comes back to the cluster.

 

[PRS]

I wish I had access to more schematics.
On a 2020 Longhorn, the 5v that feeds 1/2 the pedal also feeds the exhaust differential pressure sensor.
The 5v that feeds the other 1/2 of the pedal also feeds the AC pressure transducer.
Both 5v come from the PCM, pins 8&9 on the C2 connector.

 

[NHuott]

Interesting finds. I will break the scanner back out today and see if I can see that sensor and transducer. Where would that C2 connector be found?

 

[PRS]

Interesting finds. I will break the scanner back out today and see if I can see that sensor and transducer. Where would that C2 connector be found?

C2 is one of the main connectors on the PCM.
There is also a splice in each of those 5v supply circuits and another connector, XY105A, that could have loose pins.
I would highly recommend getting wire schematics for your specific truck year and model either from Tech Authority or the schematics in Mitchell DIY are very good as well.

 

[BigPapa]

This is the diagram for the 2017 C&C. There are TWO 5V Supplies to the APPS.

It comes from the PCM Pin #9 and supplies 5V Supply to the A/C Pressure Transducer. It then splits to feed BOTH the 5V Supplies to the APPS.

 

[Topzide]

@NHuott, As @PRS has suggested, it would be worthwhile to get schematics for your truck. I got the service and wiring bundle for mine from Tech Authority. Has been a great help. Some on TDR have access to repair info from the jobs like @BigPapa has provided. The manuals are on thumb drives. You can print out the pages your working with and make notes on them to follow when working on truck. You can learn the wiring stuff. Just have a good digital volt meter to be able to check voltages and ohms. The schematics will tell you connectors and were they are located. Good luck and keep the questions coming!

 

[NHuott]

Holy moly, all of you are very helpful! I did find and print the C1 and C2 wiring schematics and connector pin-outs, but they are crummy quality and not from my exact truck. I will look into Tech Authority to see what I can find. @BigPapa that is a great schematic. Thank you all so far for chiming in here and helping out. I will try my best to dive into this and try to get it fixed.

I got a phone call from my local dealer earlier today. They said they are "authorized" from Chrysler to "goodwill" half of the $3,500 to replace the EGR Valve. I explained the exact diagnostics I had listed here and I don't think they did even one bit of diagnostics of their own. They held on to the truck for 3 weeks on this last visit.

 

[BigPapa]

I don't think you’ve mentioned if you have any codes. With no codes, I don’t think the EGR Valve or VGT Actuator could possibly be your problem.

 

[NHuott]

@BigPapa no check engine light. If I sit in my driveway and get it to cut out over and over, it will eventually throw a "Service Electronic Throttle" code and the scanner will see a code for P06D3, but still no check engine light.

 

[User113]

I would really like to hear their explanation of the EGR valve nexus...

 

[NHuott]

They were working with FCA Engineers and opened up a Star Case. Apparently in their "diagnosis", the next step in fixing this issue is an EGR Valve replacement. This is Meadowlands CJDR in Carmel, NY. Unfortunately they are the most local dealer at about 25 minutes from us. The dealer that we bought the truck at is just over 1hr away and MUCH better, but since this is our main work truck, it is hard to let it be out of service.

Going to dive into this problem hopefully on Wednesday, as we have booked a maintenance day in the schedule.

 

[Diesel85]

They were working with FCA Engineers and opened up a Star Case. Apparently in their "diagnosis", the next step in fixing this issue is an EGR Valve replacement. This is Meadowlands CJDR in Carmel, NY. Unfortunately they are the most local dealer at about 25 minutes from us. The dealer that we bought the truck at is just over 1hr away and MUCH better, but since this is our main work truck, it is hard to let it be out of service.

Going to dive into this problem hopefully on Wednesday, as we have booked a maintenance day in the schedule.

Hope nothing else goes south on it. A 2022 3500 work truck my work needed a new camshaft and some other parts and it was out of service for 5 1/2 months due to parts problems.

 

[stickk]

Have you ever cleaned the EGR valve?
I had a dead pedal issue with my truck. Same location on my drive home. Not everyday, but several times. Had to pump the pedal a few times before it came back to life. Talked with the service manager at a dealer who used to be a diesel mechanic at the same dealership and he suggested cleaning the EGR valve. That fixed it.

 

[Joe56]

I had a dead pedal feel and then the red trouble light (lightning bolt) and service electronic throttle message. I replaced the crankshaft position sensor, and it fixed it. I found at 90k while pulling on long trip that the fan pulley bearing had failed allowing the fan pulley wheel to dip into the crankshaft and belt (grinding both) which began fraying the belt which then the frayed belt beat upon the position sensor wearing a barely noticeable edge into it. It also slapped against the vulnerable upper hose y pipe causing a leak. The OTR emergency mechanic that came to the campground to change out the pulley bearing bracket (hard to find but found a Dorman at AutoZone) and hose also picked up a new crankshaft sensor he believed was probably damaged (that no other code was thrown for) and it fixed it all including the dead pedal - the messages both disappeared.

 

[NHuott]

Thank you to all that have replied so far. Unfortunately I have not had a chance to work on the truck. It has been pouring rain like crazy here in NY and our company does a lot of drainage work.......so we have been absolutely slammed with work. Plus, my garage doesn't fit the big ole 3500, so when we're not working, it's raining and I don't necessarily feel like crawling around testing wiring in the rain! Hopefully this upcoming week allows us a maintenance day.

@stickk I have to replace my fuel filters, and I only have one set left in stock. While ordering from Genos, I remembered that we are due for an EGR cleaning. I did the CCV on my last oil change, but did not do the EGR service. I ordered the gasket kit and will be doing that cleaning when I finally get to work on the truck. Good call.