[conardh]

My 2004 throws these codes randomly. Have to turn off the engine, wait a short time and then restart engine to get full power back again. Had Advanced Auto parts put their scan tool on it and the fellow said the Pedal Position Sensor was at fault. I changed out the PPS, no help. changed out the Throttle body no help... I'm about at my wits end any thoughts?

 

[BDuncan]

I had/have the exact same issue with my '03 but only during winter. I also never got around to replacing the pedal sensor. Although the code lead to the PPS, that's not the problem. I've now seen it in several vehicles. In mine it is a combination of items, specifically the throttle position sensor connector at the front left of the intake tract. That connector is sold as a separate replacement item and I found many folks who had to replace the connector. I cleaned mine and use a little contact grease which helped a lot but the real cure was being slower on the key (starting) during cold weather. I finally noticed that it always happened when I was starting up and going out quickly and had turned the key to start very quickly. This past winter I paused a second in the key run position before turning the key to start - no issues all winter and it was doing it frequently before. My guess is the computer gets a tiny bit slower when doing all the pre-start checks and/or doesn't get the full correct signal back from the throttle position sensor (through that connector), so the computer think something is wrong and goes int "Limp Home Mode" which is what you saw. That connector likely doesn't make as good a connection during cold weather. Try this before buying any parts. I never replaced the connector either.

 

[conardh]

Thanks I'll look into the connector at the TB.

 

[the cadillac man]

Thanks I'll look into the connector at the TB.

Also check the module on the driver's side at the firewall as that is the throttle controller module I know as I had to have my PCM replaced as the data link to from this module had failed at the PCM and the dealer thought it was the tcm

 

[conardh]

Do I understand that this module is inside the truck on driver's side firewall?

 

[the cadillac man]

Do I understand that this module is inside the truck on driver's side firewall?

under the hood next to the brake booster in the corner it has two harness's going to it one from the pcm the other from the pedal sensor which goes through the firewall.

 

[the cadillac man]

the one on the inside is the truck body computer and is not the culprit.

 

[conardh]

Well I found it on the driver's side engine compartment on the fire wall has a # on it 12588923. So far I have changed out the pedal position sensor, the throttle body and the 8 connector wiring plug that supplies power to the throttle body. The problem is still there, seems like it is more likely to happen in the morning, during the first use of the truck. Sure is puzzling.

 

[BDuncan]

Try the momentary hesitation with the ignition key, pause just a quick second in run before turning to start. Also make sure the fuel fill cap is tight - that will give the same message on start up if it's not sealed.

 

[the cadillac man]

also make sure you fuel cap hasn't gone bad from age mine did and i had to replace it.

 

[conardh]

good tip I'll try it

 

[the cadillac man]

good tip I'll try it

You may have to clear the codes after I don't know if it would clear itself or not.

 

[BDuncan]

The codes will stay so they can be read later, the warning lights will go away after several start cycles.

 

[conardh]

I changed out the gas cap (no help). Also tried turning the key to on for a few seconds before starting, in my case it didn't help. One another note first drive in the morning there is some hesitation when the engine is cold, and most likely shortly there after it throws the codes. Yesterday afternoon I took the engine cover (on top of the intake) off and inspected the wiring (the wiring from the throttle body runs through this area) there for chafing, found a small spot that had been rubbing on the black tape but upon taking the tape off no wires were damaged. Far as I know the throttle control module is the only item left in this string.

 

[the cadillac man]

I changed out the gas cap (no help). Also tried turning the key to on for a few seconds before starting, in my case it didn't help. One another note first drive in the morning there is some hesitation when the engine is cold, and most likely shortly there after it throws the codes. Yesterday afternoon I took the engine cover (on top of the intake) off and inspected the wiring (the wiring from the throttle body runs through this area) there for chafing, found a small spot that had been rubbing on the black tape but upon taking the tape off no wires were damaged. Far as I know the throttle control module is the only item left in this string.

That is what it sounds like.

 

[conardh]

Well now we have changed out the gas cap, the pedal position sensor, the throttle body, the wiring connector to the TB, the throttle control module, all this did not stop the problem. Just for the hell of it what I did do this afternoon was changed out the plugs and plug wires (they had about 93000 on them) Had Bosch 4509 in there and changed them out to Bosch 4469. Guess we'll see in the morning how it acts.......

 

[the cadillac man]

If that don't fix it then the problem may be in your PCM which communicates with the throttle control module via separate data bus.
I know this from experience because the serial data bus failed in my PCM and it caused crazy crap to happen just before the PCM shut the engine down to prevent me from going out of control (thank god I wasn't in the interstate)but I was in the middle of a Walmart parking lot not as bad but could have been worse such as plowing through the Walmart store due to the fact the pedal sensor was showing that the pedal was to the floor when it wasn't.

 

[conardh]

Wow, thats crazy about the PCM, mine would have failed on the Interstate..lol Well I drove it to town the first thing this morning, I didn't notice the hesitation, and it didn't do the "reduced power" gimmick. I may be speaking too soon, but it would be nice if I never saw those codes again...Perhaps it was plugs that were end of life.....

 

[the cadillac man]

Wow, thats crazy about the PCM, mine would have failed on the Interstate..lol Well I drove it to town the first thing this morning, I didn't notice the hesitation, and it didn't do the "reduced power" gimmick. I may be speaking too soon, but it would be nice if I never saw those codes again...Perhaps it was plugs that were end of life.....

Well keep me posted if they return.

 

[conardh]

Well after all the new parts, this morning it threw the codes again....Unbelieveable!!!!!!!!