About 4-5 months ago I replaced the whole throttle pedal assembly to cure a jumpy throttle problem.

Everything was great until tonight.

I'm on the freeway tonight and the SES light comes on and the throttle pedal goes completely dead - truck maintained idle, but no throttle response at all.

I've got the following symptoms:

- Truck starts, idles and moves at idle perfectly
- I get an intermittent SES light, triggered somewhat by rough roads
- Anytime SES is lit the throttle is completely dead & truck idles fine
- Once started and idling, I can sometimes clear the SES by flooring the pedal
- After clearing, when I allow the pedal to return to idle it get an SES again
- Disconnecting battery seems to temporarily clear the SES

I think I read someone who was chewing up pedal assemblies and throttle position sensors, but I can't find that post.

Any thoughts? No codes pulled yet.

Craig

 

Well 4 - 5 months is long enough to rule out a major wiring issue. Have you tried unplugging and cleaning the connectors?

 

Unplugged and blew 'em out on the side of the road. Pins all look pretty good, no crooked or obvious trouble makers.

It's weird, if I let it sit sometimes I can get it to start with no SES light. The second that SES light comes on though -- no throttle.

 

I had a problem like that with mine one time...left me stranded in a median. All that was wrong with it was the shiny little trigger that the pedal touches to activate the switch had slipped off to the side and was not making contact with the pedal assembly in order to activate. Look at it close, with the engine off and work the pedal several times to see if the little trigger slides off to the side. We just straightend mine out the trigger with needlenose pliers and no more problems going on 3 years! Good luck!

 

Thanks Jim,

I checked the idle switch and it seems to be functioning ok -- seems to click when engaged.

I found this in another thread, but this sounds more like it only happens under hard acceleration, mine happens under any acceleration.

2001-2003 F-Series/Excursion Returns to Idle on Acceleration:
Some late 2001 trucks with the single connector accelerator pedal sensor, and 2002/03 trucks with non-adjustable pedals may return to idle on a hard acceleration. The check engine light may illuminate as well and code P0123 will be set. This is do to the computer receiving a too high accelerator pedal sensor voltage signal. This typically occurs when the pedal is held firmly against the floor. If this occurs and no problems are found, replace the accelerator pedal assembly with part number 1C3Z-9F836-BA.
TSB 04-24-11

 

I found this TSB. I've done a lot of searching on this and hadn't found it until I looked in my Amacker "Tips & Tricks" book:

2002 Super Duty Trucks with Repeat Accelerator Pedal Codes:
Some trucks built prior to 12-1-01 may exhibit repeat AP or IVS codes -- P0122, P0123, P0221; after replacement of the accelerator pedal assembly. Check the harness at the accelerator pedal and driver side shock tower for chaffing or shorts, and the AP sensor connector for damaged or pushed out pins. Repair as needed. Broadcast Message 0512.

I'm gonna check this out, but it sure would explain a lot of the pedal assembly problems and (IVS and TPS issues) I've seen on the site.

Craig

 

I'm at the point where I need some expertise.

I pulled the pedal, the IVS seems to be working fine. The switch completes the circuit when the pedal is even slightly pressed -- impedence goes to zero at every "click" of the IVS and the "click" seems to occur at the right amount of pedal travel.

I multi-metered the potentiometer in the TPS and I'm showing a constant 2.5 ohms of resistance between A and C (ground and terminal C) and a variable resistance between 0 - 1.5 ohms between A and B (ground and terminal B). Resistance on A-B varies as the pedal is pressed which is what the thing is supposed to do.

No dead spots that I can detect.

Anyone know if these ohm values seem about right?

I can't pull the codes -- no code puller and truck's driving too eratic to take it out of the driveway.

Craig

 

The only way I know to help is to bump you back to the top of the threads and see if anyone chimes in!

 

Thanks Jim,

I just replaced the pedal assembly (TPS and IVS) with a new one. It warmed up for about 3 minutes and just threw the same SES light.

I'm now thinking it's either a wiring short or a bad PCM.

I hate to have it towed to the dealer, I'm sure they'll bend me over.

Craig

 

I think I found the problem. I disconnected my chip from the PCM and no more SES light or dead throttle pedal.

I'm not sure if the chip has a short or dirty contacts, I didn't have time to mess with it, I had to haul a** to work so I can feed this nasty habit.

Craig

 

Problem fixed. PCM was bad and intermittently cutting power to the throttle position sensor. Thanks to David Lott at Diesel Innovations for figuring it out and getting me a reasonable deal on a PCM.

Just wanted to close out this thread.

Craig

 

Thanks for getting back to let us know what the problem was. Have you dared to plug your chip back in or were you able to determine that the chip did not harm your PCM.

David Lott is a good guy. I emailed him a question last night and asked him to call me and 7:30 this morning he called and gave me the answer. Great customer service.

 

I haven't plugged the chip back in yet, but I'm sure I will. Driving home last night in stock mode made me realize just how much that chip makes driving the 7.3 enjoyable.

Craig