The other day I was just taking out HID kits and of course I had the battery disconnected for electrical work to avoid shorts. When I reconnected the battery and started the truck up and threw it in reverse, it suddenly lost throttle and just went straight to idle. I rolled it into the street and parked it. I reset the PCM again and it had throttle but the CEL came on and I got these 2 codes:

P2104 Throttle Actuator Control (TAC) System - Forced Idle

P2112 Throttle Actuator Control (TAC) System - Stuck Closed

I cleared the codes and its fine now but should I check anything just to be safe? I was thinking maybe the throttle body or a throttle position sensor, but anything else I should look at?

Note: Troyer 87 Tune is on the PCM and has been for ~30k miles.

 

had this issue with mine and took it in..cleared codes and worked fine...your Throttle body is carbed up and your TPS sensor is most likely toast...known issue with the 5.4 from what I have researched.

I had Ford replace my TPS sensor, clean throttle body and change fuel filter...so far no more problems...my truck was dieing while driving and finally did it getting off the freeway..locks up steering wheel as well...not fun and when restarted sounds like it is flooded. Mine was doing it for 6-8 months about every 3-4 weeks it would just die without reason and no light...finally threw the codes.

If the TPS sensor doesn't fix your problem you may need a new throttle body.

Cost was $439 out door at Ford.

 

Sometimes, these trucks will go into fail safe mode when the battery is disconnected and reconnected.

I'd clear the codes and run it. If it runs and drives fine, don't worry about it.

 

^^It will clear the codes and be fine...eventually it will throw them again once the TPS or Throttle body starts to have more issues....your choice to fix it now or wait....I waited until it finally crapped out crapped out and replaced the TPS valve

 

No, I'm telling you, I'm about 90% certain it's 'cause the OP disconnected and reconnected the battery.

I dunno why or how, but sometimes, they do that when the battery is disconnected.

 

mine seems to do this every so often, and i haven't disconnected my battery at all recently..


i even had my tb replaced and tps.. starting to get anoying, I also have a issue of hard starts which i think is related to the tb issue.

 

Yeah after I cleared the codes its been running fine for the past few hundred miles. If it starts doing it more often I'll get the TPS replaced and clean the TB.

 

Good mornin' y'all!

I have a theory - okay, it's a S.W.A.G, ....

There is a separate 'watchdog' processor as part of the ETC system - I'm wondering if, on rare occasion, the reset, being asynchronous (two discrete systems), causes the watchdog (or the PCM) to become active first before the ETC 'regains it's senses', as a whole, as it were. It may presumably mis-interpret the lack of coherent inputs while the system is resurrecting itself as a 'preceived' problem, and trigger Failsafe.

Yeah, NVM - a stretch, lol. I need a couple more Or something stronger

BTW - there are 2 TPS's , and also 2 return springs. Nice design, actually.

Good luck!


MGD v4.2